Symbols of safety gas valves according to GOST. Check valve in the diagram. Designation of elements of hydraulic and pneumatic circuits

This article lists the most commonly used symbols of elements on hydraulic diagrams of metal-cutting machines. Images of elements of various hydraulic circuits and their description are given.

In the drawings of hydraulic circuits, normalized equipment and working bodies are depicted by symbols, highways - by lines. Special devices are depicted semi-constructively.

1. Introduction. The composition of the hydraulic drive

Semi-constructive (a) and schematic (b) representation of the hydraulic drive

In its most general form, a hydraulic drive consists of a source of hydraulic energy - a pump, a hydraulic motor and a connecting line (pipeline).

On the hydraulic diagram in Fig. 1.4 semi-constructively (a) and schematically (b) shows the simplest hydraulic drive, in which the pump 2, driven by the electric motor 11, sucks the working fluid from the tank 1 and feeds it through the filter 4 into the hydraulic system, and the maximum pressure is limited by the adjustable spring force of the safety valve 3 (controlled pressure gauge 10). To avoid accelerated wear or failure, the relief valve setting pressure must not be higher than the pump's rated pressure.

Depending on the position of the distributor handle 5, the working fluid through pipelines (hydraulic lines) 6 enters one of the chambers (piston or rod) of the cylinder 7, causing its piston to move along with the rod and working body 8 at a speed v, and the fluid from the opposite chamber through the distributor 5 and adjustable resistance (throttle) 9 is forced into the tank.

With a fully open throttle and a slight load on the working body, all the working fluid supplied by the pump enters the cylinder, the maximum speed, and the value of the working pressure depends on the losses in the filter 4, devices 5 and 9, cylinder 7 and hydraulic lines 6. Covering the throttle 9, You can reduce the speed up to a complete stop of the working body. In this case (as well as when the piston rests against the cylinder cover or an excessive increase in the load on the working body), the pressure in the hydraulic system rises, the ball of the safety valve 3, compressing the spring, moves away from the seat and the working fluid supplied by the pump (pump supply) is partially or completely bypassed through safety valve into the tank under maximum working pressure.

During prolonged operation in bypass mode, due to large power losses, the working fluid in the tank quickly heats up.

On the hydraulic diagram in the form of symbols are presented:

source of hydraulic energy -- pump 2;
hydraulic motor- cylinder 7;
guide hydraulic equipment- distributor 5;
control hydraulic equipment- valve 3 and throttle 9;
control devices- manometer 10;
working fluid reservoir- tank 1;
working environment air conditioner- filter 4;
pipelines - 6.

Hydraulic drives of stationary machines are classified by pressure, method of regulation, type of circulation, methods of control and monitoring.

2. The composition of the hydraulic drive on the example of the power head of the aggregate machine

Hydraulic system of the power head of the aggregate machine

Depending on the way the mechanisms and equipment are depicted on the schematic diagrams, they can be semi-constructive, complete and transverse.

The hydraulic system of any option has at least two main lines - pressure and drain. Purpose-built routes are connected to them, which connect hydraulic motors of one or another action with the highways. There are routes: initial, free movement, precise movement, unregulated movements, control and blocking.

On fig. 244 shows a semi-constructive, complete and transient diagram of the power head of a unit machine, which performs three transitions per cycle: fast approach, working stroke and fast retraction. On the semi-constructive scheme (Fig. 244, a) during the "Quick approach" transition, both spools are displaced by pushing electromagnets: the main spool 1 to the right, and the spool 2 of the rapid moves to the left. In this position, the oil from the pump through the first left neck of the spool 1 enters the extra-rod cavity of the cylinder 5, and from the opposite cavity of the same cylinder through the neck of the spool 2 and the second neck of the spool 1 is sent to the tank.

At the “stroke” transition, the electromagnet of the spool 2 is turned off, which causes the oil from the rod end of the cylinder 3 to flow to the drain through the speed controller 4 and then through the third neck of the spool 1 into the tank.

During the “Quick retraction” transition, the spool solenoid 1 turns off, and the spool solenoid 2 turns on again, and this changes the direction of the oil flow: from the pump through the second neck of the spool 1 into the rod end of the cylinder, and from the opposite cavity through the first neck of the spool 1 into the tank. In the "Stop" position, both electromagnets are turned off, the spools are in the position shown in the diagram, and the pressure line from the pump through the second neck of the spool 1, the neck of the spool 2 and the annular recess around the rightmost drum of the spool 1 is connected to the tank.

On the complete circuit diagram (Fig. 244, b), all elements of the hydraulic system have designations similar to those of the semi-constructive diagram, so the above description of the operation of the hydraulic drive can be used in this case as well. Comparing the diagrams, it can be seen that the design of the second diagram is simpler, and, in addition, it clearly shows the function of the spools in their various positions.

The cross-sectional diagrams (Fig. 244, e) show the same elements, and, in addition, the signs "+" and "-" and arrows of various lengths make it possible to clarify the actions of electromagnets and a power cylinder. In fact, from the consideration of diagram 1, it follows that both electromagnets are connected, and oil from the pressure line NM through one neck of the spool 1 enters the extra-rod cavity of the cylinder 3, and from the opposite cavity it is torn off through the necks of the spools 2 and 1. The piston moves in the direction " Stem forward” accelerated (long arrow).

It follows from diagram II that only spool 1 works in this transition, which remains in the same position, and turning off high-speed spool 2 turns on speed controller 4, consisting of a pressure reducing valve and a throttle. The piston at this transition moves in the same direction, but at operating speed (short arrow). Diagram III shows that spool 2 is switched on again, and spool 1 is switched off, but takes part in this transition. With this switching of the spools, oil from the NM line through the necks of both spools enters the rod cavity of the cylinder, and from the opposite cavity it drains through the second neck of the spool 1. The piston changes its speed and direction. From diagram IV it follows that both spools are disabled, and the pressure line is connected to the tank through their necks, and therefore, in this position, even when the pump is running, the hydraulic drive is turned off.

3. Symbols of hydraulic drive elements on hydraulic diagrams

Conditional graphic designations serve for functional representation of elements of a hydraulic drive and consist of one or several basic and functional symbols. In accordance with DIN ISO 1219-91, GOST 2.781-96 and 2.782-96, the following basic symbols are used:

continuous line- main hydraulic line (suction, pressure, drain), electric line;
dotted line- control line, drainage, indication of an intermediate position;
dot-dash line- combining several components into a single unit;
double line- mechanical connection (shaft, rod, lever, rod);
circle- pump or hydraulic motor, measuring device (pressure gauge, etc.), check valve, swivel joint, hinge, roller (with a dot in the center);
semicircle- rotary hydraulic motor;
square (with a joint perpendicular to the sides)- hydraulic apparatus, drive unit (except for electric motor);
square (with corner connection)- air conditioning of the working environment (filter, heat exchanger, lubricator);
rectangle- hydraulic cylinder, hydraulic device, adjustment element;
open top rectangle- tank;
oval- accumulator, gas bottle, pressurized tank.

Functional symbols include triangles (black - hydraulics, white - pneumatics), various arrows, lines, springs, arcs (for throttles), the letter M for electric motors.

Symbols of the hydrodistributor

In the designation of the hydraulic valves, there are several squares nearby (in accordance with the number of positions, i.e. fixed positions of the spool relative to the body), and hydraulic lines are connected to one of the positions (initial): P - pressure, T - drain, A and B - for connecting hydraulic motor. The number of hydraulic lines can be different: P, T, A and B - for four-line devices; P, T and A - for three-line; P, T1 (TA), T2 (TV), A and B - for five-line, etc.

Examples of symbols for hydraulic valves

On fig. 1.6, a shows the symbol of a four-line three-position apparatus (4/3 hydraulic distributor) with electrical control from two pushing electromagnets (Y1 and Y2) and spring return to the initial position 0, in which all lines are locked. When the electromagnet Y1 is turned on, the spool moves to the right, and you can determine the connection option for the lines by mentally moving the square corresponding to position a to the place of the square of position 0. As you can see, the lines P-B and A-T are connected. When the electromagnet Y2 is turned on in position b, a connection of P-A and B-T occurs. If it is necessary to show the connection of lines in intermediate positions at the moment of switching from one position to another, dotted squares are added between the main positions (Fig. 1.6, b). In hydraulic valves controlled, for example, from a proportional electromagnet Y3 (Fig. 1.6, c), many different intermediate positions are possible, and two horizontal lines are added to the symbol. Conventional graphic designations of the main elements of the hydraulic drive are given in table. 1.1.

An example of a hydraulic circuit

Letter position designations of the main elements of the hydraulic circuit:

BUT- Device (general designation)
AK- Hydraulic accumulator (pneumatic accumulator)
AT- Heat exchanger
B- Hydraulic tank
VD- Dehumidifier
VN- Valve
WT- Hydrodisplacer
G- Air silencer
D- Hydraulic motor (pneumatic motor) rotary
DP- Flow divider
DR- Hydrothrottle (pneumothrottle)
ZM- Hydraulic lock (pneumatic lock)
To- Hydraulic valve (pneumatic valve)
HF- Hydraulic valve (pneumatic valve) time delay
KD- Hydraulic valve (pneumatic valve) pressure
KO- Hydraulic valve (pneumatic valve) return
KP- Hydraulic valve (pneumatic valve) safety
KR- Hydraulic valve (pneumatic valve) reducing
KM- Compressor
M- Hydraulic motor (pneumatic motor)
MN- Manometer
MP- Hydrodynamic transmission
MR- Oil sprayer
MS- Butter dish
MF- Hydrodynamic clutch
H- Pump
ON THE- Axial piston pump
NM- Pump-motor
NP- Vane pump
HP- Radial piston pump
PG- Pneumohydroconverter
ETC- Hydraulic converter
R- Hydrodistributor (pneumatic distributor)
RD- Pressure switch
RZ- Hydraulic device (pneumatic device) spool
RK- Hydraulic device (pneumatic device) valve
RP- Flow regulator
PC- Receiver
With- Separator
joint venture- Flow totalizer
T- Thermometer
TR- Hydrodynamic transformer
HC- Air vent device
US- Hydraulic booster
F- Filter
C- Hydraulic cylinder (pneumatic cylinder)

For the depiction of various elements and devices on hydraulic diagrams, symbols and graphic symbols are used - All sizes of the symbolic graphic symbols specified in the standards can be proportionally changed.

In addition, other graphic symbols can be used - Graphic symbols are performed with lines of the same thickness as the communication lines.

To simplify the drawing of the circuit (reducing breaks and intersections of communication lines), it is allowed to depict conventional graphic symbols rotated by an angle multiple of 90 or 45 degrees, as well as mirrored in a state of compression).

It is allowed to place various technical data on the diagrams, the nature of which is determined by the purpose of the diagram - They can be located near the graphic (on the right or above) or in the free field of the diagram (preferably above the main inscription).

Near the graphic designations of the elements, their alphanumeric positional designations are indicated, and in the free field of tables, diagrams, textual indications - The alphanumeric designation consists of an alphabetic designation (BO) and a serial number affixed after the BO - BO schemes are determined by GOST 2.704-76 - For designations, capital letters of the alphabet are used, which are initial or characteristic for the name of the element - Letters and numbers in positional designations on the diagram are made in the same size font - Ordinal numbers must be assigned in accordance with the sequence of elements or devices on the diagram from top to bottom in the direction from left to right .

Technical data on the elements of the circuits must be recorded in the list of elements - At the same time, the connection of the list with the conditional graphic designations of the elements should be carried out through reference designations - For simple diagrams, all information about the elements is allowed to be placed near the conditional graphic designations on the shelves of leader lines - The list of elements is drawn up in in the form of a table and placed on the first sheet of the diagram above the main inscription, the distance between them must be at least 12 mm - Also, the list can be made in the form of an independent document in A4 format.

In the main inscription indicate the name of the product and the name of the document - In the columns of the list indicate the following data: in the column - the positional designation of the element, device or designation of the functional group on the diagram; in the column - the name of the 26 element in accordance with the document on the basis of which it was applied and the designation of this document - If it is necessary to indicate the technical data of the element, it is recommended to indicate them in the column.

It is allowed to indicate on the diagram flow parameters in communication lines: pressure, flow, temperature, etc., as well as parameters to be measured at control taps.

4. Symbols on hydraulic diagrams adopted in the USSR

The method of depicting lines in the hydraulic systems of machine tools is non-standard - The most convenient is the following method, adopted by many organizations and used in the technical literature:

highways connecting various devices - with thick solid lines;
highways made inside the apparatus - thin solid lines;
drainage lines - with thin dashed lines - The symbols of the devices are drawn with contour solid lines of normal thickness - The junctions of the lines are indicated by a line and a dot (pos - 43, fig - 4); intersections without connections should be highlighted with a bypass sign (pos - 44, fig - 4).

Figure - 4 shows the main symbols on hydraulic diagrams adopted in the USSR:

general designation of an unregulated pump without specifying the type and type;
general designation of an adjustable pump without specifying the type and type;
vane pump (rotary vane) double action unregulated types G12-2, G14-2;
double vane pumps (rotary vane) with different capacities;
unregulated gear pump type G11-1;
unregulated radial piston pump;
adjustable radial piston pump type PPR, NPM, NPCM, NPD and NPS;
pump and hydraulic motor axial-piston (with swash plate) unregulated;
pump and hydraulic motor axial-piston (with swash plate) adjustable types 11D and 11P;
general designation of an unregulated hydraulic motor without specifying the type;
general designation of an adjustable hydraulic motor without specifying the type;
plunger hydraulic cylinder;
telescopic hydraulic cylinder;
single-acting hydraulic cylinder;
double-acting hydraulic cylinder;
hydraulic cylinder with double-sided rod;
hydraulic cylinder with differential rod;
single-acting hydraulic cylinder with piston return with spring rod;
servomotor (torque hydraulic cylinder);
apparatus (main symbol);
spool types G73-2, BG73-5 controlled by an electromagnet;
spool with manual control type G74-1;
spool with cam control type G74-2;
check valve type G51-2;
pressure spool type G54-1;
pressure spool type G66-2 with check valve;
two-way spool type G74-3 with a check valve;
safety valve type G52-1 with overflow spool;
pressure reducing valve type G57-1 with a regulator;
four-way valve, type G71-21;
four-way three-position crane type 2G71-21;
three-way valve (three-channel);
two-way valve (through passage);
damper (unregulated resistance);
choke (unregulated resistance) types G77-1, G77-3;
choke with regulator types G55-2, G55-3;
general designation of the filter;
lamellar filter;
mesh filter;
pressure switch;
pneumatic accumulator;
manometer;
pipe connection;
pipe intersections without connection;
plug in the pipeline;
reservoir (tank);
drain;
drainage.

Features and benefits of hydraulic drive

hydraulic drive- a set of devices (which include one or more volumetric hydraulic motors) designed to drive mechanisms and machines by means of a pressurized working fluid. Hydraulic drives are one of the most intensively developing sub-sectors of modern mechanical engineering. Compared to other known drives (including electromechanical and pneumatic ones), hydraulic drives have a number of advantages. Let's consider the main ones.

Possibility of obtaining great strength and power with limited sizes of hydraulic motors. So a hydraulic cylinder with a piston diameter of 100 mm at a pressure of 70 MPa, which can be created by a hand pump, develops a force of about 55 tons, so with the help of special jacks, you can manually raise the bridges.
High performance ensuring the required quality of transient processes. Modern hydraulic drives, such as test benches, are capable of working out a given impact with a frequency of up to several hundred hertz.
Wide range of stepless speed control with good fluidity. For example, for hydraulic motors, the control range reaches 1:7000.
Ability to protect the hydraulic system from overload and precise control of the acting forces. The force developed by the hydraulic cylinder is determined by the area of its piston and the working pressure, the value of which is set by setting the safety valve and controlled by a pressure gauge. For a hydraulic motor, the magnitude of the developed torque is proportional to the working volume (overall dimensions of the hydraulic motor) and the operating fluid pressure.
Obtaining rectilinear motion using a hydraulic cylinder without kinematic transformations (an electromechanical drive usually requires a gearbox, screw or rack gear, etc.). By selecting the areas of the piston and rod chambers, it is possible to provide a certain ratio of forward and reverse speeds. An important circumstance is the ideal protection of hydraulic cylinders from external contaminants, which makes it possible to successfully operate hydraulic drives, for example, in mining equipment, excavators and other machines operating in conditions of increased environmental pollution, and in some cases even under water.
Extensive range of control mechanisms, from manual to direct control from a personal computer, allows you to optimally use hydraulic drives for automating production processes in various branches of technology, successfully combining the exceptional power and dynamic qualities of hydraulics with the ever-expanding capabilities of microelectronics and integrated control systems.
Wide range of energy storage and recovery options provide a good basis for the development of modern, energy-efficient hydraulic drive mechanisms.
Layout of hydraulic drives mainly from unified products, mass-produced by specialized factories, provides a reduction in manufacturing costs, an increase in quality and reliability, the convenience of placing on a machine a large number of compact hydraulic motors (hydraulic cylinders or hydraulic motors) powered by one or more pumps, opens up wide opportunities for repair and modernization.

Bibliography:

Biryukov B.N. Hydraulic equipment of machine tools., 1979
Sveshnikov V.K. Machine hydraulic drives: A Handbook - 6th ed. revised and additional - St. Petersburg: Polytechnic, 2015
Kucher A.M., Kivatitsky M.M., Pokrovsky A.A., Metal-cutting machines (Album), 1972

Description

Designation on the diagram

Basic lines

Pilot lines

Drainage lines

Boundary lines

Electrical lines

Direction of fluid flow (hydraulics)

Gas direction (pneumatic)

Direction of rotation

Lines crossing

Line connection

Quick Coupling (BRS)(Quick Coupling)

flexible line

Variable Component

Pressure Compensated Components

Open type tank (atmospheric pressure in the tank) (Reservoir Vented)

Overpressure tank (closed type)(Reservoir Pressurized)

Drain line to tank (above liquid level)

Drain line to tank (below liquid level)

Electric Motor

Spring Loaded accumulator

Gas accumulator (Gas Charged accumulator)

Heater

Heat exchanger (cooler)(Cooler)

Filter

pressure gauge

Thermometer

Flow meter

Pressure relief valve ("breather") (Vented Manifold)

Pumps & motors

Fixed Displacement Pump (Fixed Displacement)

Fixed displacement pump (unregulated) reversible

Variable Displacement Pump (Variable Displacement)

Variable displacement pump (adjustable) reversible

Fixed displacement hydraulic motor (non-adjustable)

Fixed displacement hydraulic motor (non-adjustable) reversible

Variable displacement hydraulic motor (adjustable)

Variable displacement hydraulic motor (adjustable) reversible

Pump-motor (unregulated) (Combined pump and motor)

Pump-motor (adjustable) (Combined pump and motor)

Hydrostatic transmission

hydraulic cylinders

Single acting cylinder

Double Acting Cylinder

Double acting cylinder with double end rock(Synchronous)(Double actin, Double end rock)

Cylinder with damper(Cushion)

Cylinder with adjustable damper (Adjustable Cushion)

Double-acting differential hydraulic cylinder (differential piston)

Valves

Check valve

Check valve controlled (Check valve)

Shuttle valve

Throttle valve-fixed output

Throttle valve-adjustable output

Throttle adjustable with check valve

Flow divider (Flow dividing valve)

Normally closed valve

Normally open valve

Pressure limiting valve, Fixed

Pressure limiting valve - Variable

Pilot operated, External drain line valve

Pilot operated, internal drain line valve

Pressure Relief Valve(safety valve))

Pressure Switch

Crane (Manual Shut-Off valve)

Control type

Spring

Spring return

Manual control

Button

Lever (Push-Pull Lever)

Pedal or Treadle

Mechanical control

Detent

Pilot control of external pressure (Pilot Pressure)

Pilot Pressure - Internal Supply

Hydraulic operation

Pneumatic operation

Pneumatic-hydraulic operation

Solenoid

Motor operation

Servo Motor

Pressure Compensated

Distributors (Directional valves)

2 position distributor

3 position distributor

2-position valve without fixation

2-position, with two extreme positions and neutral

2 position, 2 line

2 position, 3 line

3 position, 4 line

Valve with mechanical feedback (Mechanical feed back)

hydrostat.ru

Graphic designations of pipeline fittings | Pipeline accessories

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Conditional (graphical) images of pipeline fittings are used in drawing up the network detailing, in which all nodes and components of the water supply network are pipeline shut-off and control valves and fittings, etc. are depicted schematically (not to scale) by symbols. Designations of pipeline fittings according to the TsKBA system and others are given HERE.

Detailing of the water supply network is used for the installation of sections of pipelines, fittings and fittings, and other equipment. Based on the detailing, a specification of fittings and fittings required for the network device is compiled.

Below are the main symbols of pipeline fittings:

fittings	Designation
Shut-off valve (valve) Shut-off valve (valve) angular


Globe valve Angle ball valve
Valve (valve) Valve (valve) regulating angular
Valve (valve) three-way
Globe safety valve Angle safety valve
Pressure regulator "to yourself" After pressure regulator
Check valve Swing check valve (slam) receiving with mesh
Throttle valve
pressure reducing valve

Quick opening valve (NO) Quick closing valve (NC)

www.podvod.ru

types, device, principle of operation, installation

The check valve allows liquid to flow through the pipeline in one direction and prevents it from flowing in the opposite direction. It is an important component of any water supply, heating, sewerage and industrial process installations. It is also used in leak prevention systems for washing machines and dishwashers. Locking devices have a variety of designs, each of which has its own advantages and scope. Their common feature is that the valve opens when a certain pressure is reached and closes when the pressure drops below the set value.

The appearance of the check valve

Check valve internals

What does the check valve for water for a pump consist of and how does it work

The check valve for water consists of the following parts:

corps;
spool - a movable executive body, which in turn is assembled from a pusher, spool plates and an elastic gasket sandwiched between them;
sealing gasket;
springs (with the exception of gravity-type lifting devices).

The device of the check valve for water varies depending on its type.

The body is most often made of brass - this material is not subject to corrosion and the effects of chemically active substances contained in water in the form of a solution, it is strong and durable.

Sometimes a chrome or nickel coating is applied to the outside by galvanic method. The spool parts are also made of brass or durable plastic. The water check valve gasket is most often rubber or silicone. And finally, the spring is made of stainless steel with a high coefficient of elasticity.

How does a check valve work

The principle of operation of the check valve is that the spool moves along the pusher (rod) and can occupy extreme positions in the spool chamber. The pressure of water in the forward direction compresses the spring and presses the plates to the open position. Water passes through the gate. If the pressure drops, the spring presses the plates and the gasket sandwiched between them to the seat and closes it. The principle of operation of the lift-type check valve is almost the same, only the mass of the spool and the force of attraction play the role of a spring.

Types of check valves

Depending on the type of locking element, the following types of check valves are distinguished:

lifting type. The disc check valve poppet moves up and down. After pressure is applied in the working direction, the valve opens, and when the pressure drops or the direction of fluid movement changes, it closes under the action of a spring or its own weight.
Turning. The non-return valve is a flap that rotates and opens under the pressure of the liquid, and closes with the force of the spring when the pressure drops.
Ball. The flow is blocked by a ball pressed against the valve seat by a return spring. The pressure of the liquid presses the ball from the seat, opening the passage for water.
Wafer type. It can be a disk-type design similar to a lifting one, but the plate moves along the flow axis, and a double-leaf damper consists of two wings that fold towards each other. The double-leaf design has minimal flow resistance when open.

Lift Type Check Valve Swing Type Check Valve Ball Type Check Valve Wafer Type Check Valve

According to the material of manufacture, there are such types of check valves as:

Brass - reliable and wear-resistant, most often used in everyday life.
Cast iron - inexpensive, but prone to rust, used only on main pipes.
Stainless - the highest quality and most reliable, but also the most expensive. Used in the most critical systems.

Depending on the method of fastening the water return valve, there are:

Coupling - the water valve is included in the pipe break using two threaded couplings. Most common in domestic systems.
Flanged - the gate valve is connected using flange connections. It is mainly used for cast iron devices on large pipes.
Wafer - the shut-off valve is located between two flanges, which are pulled together with through studs. Also used on main pipelines.

Valve locations

In domestic water supply and heating systems, there are many places where a check valve needs to be installed:

At the entrance to the apartment from the centralized supply of hot water.
After the counter to protect it from water hammer.
Before the pumping station of the individual water supply system - to stop the leakage of water from the pipes after the power is turned off.
At the end of a water intake hose lowered into a well or well, or after a submersible pump - to prevent water from running off when the pump stops.
At the inlet of an electric or gas water heater - to prevent the exit of heated and expanded water into a cold main.
In the leakage protection system of washing machines and dishwashers.

These are the most common installation locations. If necessary, such a water valve is installed in all places where it is necessary to ensure the water flow is strictly in one direction.

How to make the right choice

To choose a check valve that will work long and reliably in harmony with other elements of your plumbing or heating system, you need to pay attention to the following points:

Appointment. The selected device type must match it. So, for example, lift-type valves with gravity action can be installed strictly in the position provided for by the design, so that the stroke of the stem is perpendicular to the ground surface.
Attachment method. It is selected at the same time as designing the connectors to which the valve will be connected, in order to avoid piling up unnecessary adapters. For domestic systems, coupling connections are usually used.
The size. Must exactly match the diameter of the pipeline. The use of a smaller diameter gate connected through adapters will reduce the reliability of the design and create an increased resistance to flow.
Material. For hot liquids, it is better to use brass or stainless steel, since polypropylene has a noticeably reduced resource at high temperatures.

It is difficult for a novice home master to take into account all the nuances, so in case of doubt, do not hesitate to consult an experienced engineer.

The device of valves of different types

The choice and installation of a check valve for water depends on its design features. The water valve can belong to such types as:

Coupling spring check valve

The body of the device consists of two cylinders connected by a threaded connection. The spool consists of a plastic pusher, a pair of plates and an elastic gasket. The normal position of the shutter is closed, when the pressure of the liquid is applied and it reaches the set value, it depresses the spring, and the valve for water opens. When the pressure drops, the spring returns the spool to its place, closing the shutter.

Rotary petal

The spool in this embodiment is made not axial, but rotary, and the axis is placed above the clearance of the shutter. When fluid pressure is applied, it depresses the flap and the valve opens. When the pressure drops, the damper lowers under the action of gravity or a return spring and closes the gap. When installing such a device, it is important to observe the “top” marking and the maximum possible slope specified in the documentation. In large devices, when the damper returns, it hits the saddle with a powerful blow, which can lead to water hammer and even to failure of the device. To prevent this, the design has to be complicated and shock-damping elements added. The design allows you to create valves of large diameters, little sensitive to the presence of suspensions and other inclusions in the liquid.

ball model

The mode of operation and device are very similar to the poppet spring valve. The role of the locking part is played by a ball pressed against the seat by a spring. It is mainly used for pipes of small diameter, in household plumbing systems. Such a check valve with an equal cross section has larger external dimensions than a poppet valve.

lifting type product

The spool rod in this case is placed vertically, under water pressure the spool rises, opening the shutter. When the pressure drops, the stem drops and the valve closes. A restriction is imposed on the installation of such devices - it can only be designed on horizontally located pipes. An important advantage of such structures is the possibility of repairing the spool without removing the entire body. The downside is the increased requirements for the purity of the liquid.

Check valves for submersible pumps

To organize uninterrupted water supply in private homes using a submersible pump, it is especially important to install a check valve immediately after the pump. This will prevent water from flowing back into the well when the pump is turned off and eliminate the need to refill the system with water each time.

With a well of great depth, a sufficient diameter of the pipeline and the remoteness of the well from the house, we can talk about tens of liters of water. In many models of submersible pumps, such a valve is installed at the factory. If it is not there, then, as a rule, a brass device with axial movement of the spool and a return spring is chosen. The lumen of the shutter must be no less than the inner diameter of the pipeline, so as not to create additional resistance to flow.

Check valve installation rules

It is not enough to make the optimal choice of the device model, it is also necessary to install it correctly.

Incorrect installation of the valve may result in the need to repair or replace it, which can be very time consuming, especially if it is installed in the well.

If an arrow is drawn or stamped on the body, then it must be installed strictly with the arrow up, even despite the presence of a return spring.
If the depth of the well or well (more precisely, the distance to the water surface) is small, then the check valve is placed directly at the inlet to the pressure apparatus.
In the case when the depth of the well is more than 8 m, it is better to put the device at the water intake, supplementing it with a mechanical coarse filter.
When using a submersible pump, the valve must be installed at its outlet.
With a large distance to the well, it is better to put two gates - at the outlet of the pressure device and at the entrance to the house.

It is impossible to foresee all options, therefore, before starting installation, you should show the diagram of your water supply or heating system to a qualified and experienced plumbing engineer.

How to install check valves for pumping stations

A check valve for joint operation with a pumping station should be selected at the design stage. In some pump models, such valves are included in the design, for the rest there are several rules:

For vacuum type (suction) pumps, the valve is mounted at the pump outlet, before the hydraulic accumulator.
With a large depth of the well and at a large distance from the well on the surface, an additional device should be installed at the water intake.
For pressure pumps lowered into the well, the valve is mounted on the outlet pipe.

In addition, during installation, the direction of flow indicated on the body must be strictly observed, and all connections must be carefully sealed.

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what is it for, principle of operation, types

A mandatory element of equipping autonomous water supply systems in summer cottages and country houses is a check valve. It is such a technical device, which can have a different design, that ensures the movement of fluid through the pipeline in the required direction. Check valves installed in the autonomous water supply system reliably protect it from the consequences of emergency situations. Relating to direct acting valves, check valves operate automatically, for which the energy of the working medium transported through the pipeline system is used.

Purpose and principle of operation

The main function that a check valve for water performs is that it protects the water supply system from critical parameters of the flow of liquid transported through the pipeline. The most common cause of critical situations is the shutdown of the pumping unit, which can lead to a number of negative phenomena - draining water from the pipeline back into the well, spinning the pump impeller in the opposite direction and, accordingly, breakdown.

Installing a check valve on water allows you to protect the plumbing system from the listed negative phenomena. In addition, the water check valve prevents the consequences that water hammer causes. The use of check valves in pipeline systems makes it possible to make their work more efficient, as well as to ensure the correct functioning of the pumping equipment that such systems are equipped with.

The principle of operation of the check valve is quite simple and is as follows.

The flow of water entering such a device under a certain pressure acts on the locking element and depresses the spring, with which this element is held closed.
After compressing the spring and opening the locking element, water begins to move freely through the check valve in the required direction.
If the pressure level of the working fluid flow in the pipeline drops or the water begins to move in the wrong direction, the spring mechanism of the valve returns the locking element to the closed state.

By acting in this way, the non-return valve prevents the formation of unwanted backflow in the piping system.

When choosing a model of a valve installed on a water supply system, it is important to know the regulatory requirements that manufacturers of pumping equipment impose on such devices. The technical parameters by which, in accordance with these requirements, a check valve for water is selected are:

operating, test and nominal closing pressure;
landing part diameter;
conditional throughput;
tightness class.

Information on what technical requirements the check valve for water must meet is usually contained in the documentation for pumping equipment.

To equip domestic water supply systems, spring-type check valves are used, the diameter of the conditional passage is in the range of 15–50 mm. Despite their compact size, such devices demonstrate high throughput, ensure reliable operation of the pipeline, low noise and vibration levels in the pipeline system on which they are installed.

Another positive factor in the use of check valves in the water supply system is that they help reduce the pressure created by the water pump by 0.25–0.5 atm. In this regard, the check valve for water allows you to reduce the load both on individual elements of pipeline equipment, and on the entire water supply system as a whole.

Design features

One of the most common materials from which the body part of the water return valves is made is brass. The choice of this material is not accidental: this alloy demonstrates exceptionally high resistance to chemically aggressive substances, which can be present in the water transported through the pipeline in a dissolved or suspended state. Such substances, in particular, include mineral salts, sulfur, oxygen, manganese, iron compounds, etc. The outer surface of the valves, which is also exposed to negative factors during their operation, is often protected with a special coating applied by the galvanic method.

The check valve device assumes the presence of a spool, for the manufacture of which brass or durable plastic can also be used. The sealing gasket present in the design of the check valve can be rubber or silicone. For the manufacture of an important element of the locking mechanism - springs - stainless steel is usually used.

So, if we talk about the structural elements of the spring check valve, then this device consists of:

housing of a composite type, the elements of which are interconnected by means of a thread;
a locking mechanism, the design of which includes two movable spool plates mounted on a special rod, and a sealing gasket;
spring installed between the spool plates and the seat at the outlet of the through hole.

The principle of operation of the spring check valve is also quite simple.

The flow of water entering the check valve at the required pressure acts on the spool and depresses the spring.
When the spring is compressed, the spool moves along the stem, opening the orifice and allowing fluid to flow freely through the device.
When the pressure of the water flow in the pipeline, on which the check valve is located, drops, or in cases where such a flow begins to move in the wrong direction, the spring returns the spool to its seat, closing the through hole of the device.

Thus, the scheme of operation of the check valve is quite simple, but nevertheless ensures the high reliability of such devices and the efficiency of their use in pipeline systems.

Main types

Having figured out how the check valve installed in the plumbing system works, you should also understand how to choose it correctly. On the modern market, various types of check valve devices are offered, the design, material of manufacture and the scheme of operation of which can vary greatly.

Coupling Type Spring Check Valve

The valve body of this type consists of two cylindrical elements connected to each other by means of a thread. The locking mechanism includes a plastic stem, upper and lower spool plates. The position of the elements of the locking mechanism in the closed state, as well as their opening at the moment when the pressure of the water flow reaches the required level, is provided by a spring. Between themselves, the constituent elements of the body are connected using a sealing gasket.

Spring check valve with brass spool and spherical spool chamber

Distinctive features of this type of shutters are easy to see even in the photo. The brass body of such a valve in its middle part, where the spool chamber is located, has a spherical shape. This design feature allows you to increase the volume of the spool chamber and, accordingly, the throughput of the check valve. The locking mechanism of this type of water valve, which is based on a brass spool, works on the same principle as in valve devices of any other type.

Combination spring type check valve with drain and air vent

For many of those who decide to independently engage in the installation of the pipeline system, the question often arises as to why a check valve is needed, equipped with drainage and air vent systems. The use of check valves of this type (especially for equipping pipelines through which hot working fluids are transported) makes it possible to simplify the process of installation and maintenance of such systems, increase their reliability, reduce the total hydraulic pressure, and reduce the number of field connections.

On the valve body of this type, which can even be seen in the photo, there are two nozzles, one of which is used to mount the air vent, and the second serves as a drainage element. The branch pipe for the air vent, on the inner surface of which a thread is cut, is located on the device body above the spool chamber (its receiving part). Such a pipe is needed to bleed air from the pipeline system, for which a Mayevsky crane is additionally used. The purpose of the branch pipe, which is located on the opposite side of the body - at the outlet of the valve, is to drain the liquid accumulated after the valve device from the system.

If a horizontal non-return valve is installed, its air outlet can be used to mount a pressure gauge. If you put the combined check valve vertically on the pipeline, then its drainage pipe can be used to drain the water accumulated after such a device, and the air vent pipe can be used to remove air plugs from that part of the pipeline that is located before the check valve. That is why, when deciding how to install a combined type check valve, you should clearly understand what functions such a valve should perform.

Spring loaded valves with polypropylene body

Check valves, the body of which is made of polypropylene, even if you look at the photos of such devices, outwardly very much resemble oblique bends. These types of check valves, for the installation of which the polyfusion welding method is used, are installed on pipelines also made of polypropylene. An additional oblique branch in the design of gates of this type is necessary to accommodate the elements of the locking mechanism in it, which facilitates the maintenance of such a device. Thanks to this constructive solution, it is not difficult to carry out maintenance and repair of this type of check valve - it is enough to remove the elements of the locking mechanism from its additional branch without violating the integrity of the device body and the tightness of its installation in the pipeline system.

Check valves of other types

Other types of non-return valves can be installed in pipeline systems designed for transporting water.

The flap check valve is equipped with a special locking element - a spring-loaded petal. A big disadvantage of this type of shutters is that when they are triggered, significant shock loads are created. This negatively affects the technical condition of the gate device itself, and can also cause a hydraulic shock in the pipeline system.
Double-leaf type check valve devices are compact in size and light in weight.
The lifting coupling check valve includes a spool freely moving along the vertical axis as a locking element. The operation of the locking mechanism can be based on the gravitational principle, when the spool returns to the closed state under the influence of its own weight. A spring can also be used for this purpose. If you decide to install a gravity check valve on the pipeline, keep in mind that such a device can only be installed in vertical sections of the system. Meanwhile, the gravity valve is characterized by simple structure, while showing high reliability during operation.
There are check valves, the locking element of which is a spring-loaded metal ball. The surface of such a ball can be additionally covered with a layer of rubber.

When deciding which check valve is better and whether an expensive valve of a more complex design is needed in the pipeline system, one should first of all get acquainted with the technical characteristics of such a device and compare them with the operating parameters of the pipeline system. The main purpose of the check valve, as mentioned above, is to pass water through the pipeline in the right direction and prevent the flow of liquid from moving in the opposite direction. In this regard, the check valve for water should be selected based on the pressure under which the water flow moves in the pipeline. Naturally, it is necessary to take into account the diameter of the pipes on which such a valve should be installed.

When installing the pipeline, it should also be borne in mind that the check valve can be installed in various ways. Flanged and wafer type check valves are installed on pipes of large diameter, and sleeve valves are installed on pipes of small diameter. The welded method of installing check valves is mainly used when mounting on polypropylene and metal-plastic pipes.

If you choose the right check valve and the way it is installed, such a device will not only last a long time, but also ensure the correct operation of the entire pipeline system.

How to install correctly

Having dealt with the question of why a check valve is needed, and with its role in the pipeline system, you should also study the rules for installing it on an already operating or just being created pipeline. Such devices are mounted on various elements of pipeline systems:

on pipelines of autonomous and centralized water supply;
on suction lines served by deep and surface pumps;
in front of boilers, storage water heaters and water meters.

If you are interested in check valves that can be installed both vertically and horizontally, choose not gravity, but spring models. You can find out in which direction the water flow should move through the valve using a special arrow printed on the body of the device. When installing sleeve-type check valves, be sure to use FUM tape for good sealing. In addition, one should not forget that check valves need regular maintenance, so they must be installed in accessible places in the pipeline.

When installing a check valve on the suction line of a submersible pump, care should be taken to install a coarse filter in front of such a device, which will prevent mechanical impurities contained in underground water from entering the inside of the device. A perforated or mesh cage can also be used as such a filter, in which a check valve is placed at the inlet end of the suction line of the submersible pump.

When installing a check valve on an already operating pipeline, you must first disconnect the system from the water supply and only then install the shut-off device.

How to make a check valve yourself

The simple design of the check valve allows, if necessary, to make it yourself.

To solve this problem, you will need the following materials and tools:

a tee with an internal thread, which will serve as a body;
a threaded coupling on the outer surface - a homemade check valve seat;
rigid spring made of steel wire;
a steel ball, the diameter of which should be slightly smaller than the diameter of the hole in the tee;
steel threaded plug, which will act as a stop for the spring;
a standard set of locksmith tools and a FUM sealing tape.

Elements of pipeline designations on the diagrams

Conditional graphic designations for hardware-technological schemes

Name	Designation
I. Piping elements
1. Piping (general purpose) 2. Piping connection 3. Crossing of pipelines (without connection) (GOST 2.784-70) 4. Flexible pipeline, hose (GOST 2.784–70)
5. Detachable connection of pipeline elements: 5.1. General designation 5.2. Flanged 5.3. Choke threaded 5.4. Coupling threaded 6. End of the pipeline for a detachable connection: 6.1. General designation 6.2. Flanged 6.3. Choke threaded 6.4. Coupling threaded Designations on technological schemes.
Designations on technological schemes: 7. End of the pipeline with a plug (plug): 7.1. General designation 7.2. flanged 7.3. Threaded
II. Fittings - Symbols on technological schemes.
8. Shutoff valve (valve) (GOST 2.785-70) 8.1. Checkpoint 8.2. Angular 9. Valve (valve) three-way (GOST 2.785-70)
10. Check valve (non-return). The movement of the working fluid from the white triangle to the black one (GOST 2.785-70) 11. Safety valve (GOST 2.785-70)
Symbol on the diagram. 12. Throttle valve (GOST 2.785-70) 13. Pressure reducing valve (movement from left to right) (GOST 2.785-70) 14. Automatic air valve (ventuz) (GOST 2.785–70)
15. Air intake from the atmosphere (GOST 2.780-68) 16. Filling neck, filling fitting (GOST 2.780–68)
17. Connecting device to other systems (test, washing, transport, etc.) (GOST 2.780-68) 18. Gate valve (GOST 2.785–70) Symbol on the diagram.
19. Rotary shutter (GOST 2.785-70) 20. Crane (GOST 2.785–70)
21. Angle crane (GOST 2.785-70) 22. Three-way valve (GOST 2.785-70) 23. Four-way valve (GOST 2.785-70)
Designation on the diagram. 24. End valve (GOST 2.785-70) 25. Laboratory crane (GOST 2.785-70)
26. Fire crane (GOST 2.785-70) 27. Nozzle (GOST 2.780-68)
28. Aspiration device (local exhaust) (GOST 2.786–70)
29. Ventilation damper (GOST 2.786-70) 30. Shiber (GOST 2.786–70) Designation on the diagram.
31. Check valve automatic in explosive design (ventilation) (GOST 2.786-70) 32. Fire-retardant damper (ventilation) (GOST 2.786-70) 33. Discharge into the sewer
34. Condensate drain

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Designation of elements of hydraulic and pneumatic circuits

Hydraulic and pneumatic diagrams help you understand how hydraulic and pneumatic equipment functions. Individual elements of hydraulic and pneumatic circuits have their own symbols. Below are the symbols that you will meet on hydraulic diagrams.

Pumps and compressors.

designation on hydraulic diagrams.

Pressure management.

Pressure controls.

Designation of various types of valves that control pressure in hydraulics on hydraulic diagrams. Designation of hydraulic motors.

Valves.

Designation of valves on hydraulic diagrams.

Two paths for flow, one connection closed. In the following examples, the first digit indicates the number of connections. The second digit indicates the number of working positions. 3/2 control valve; control by pressure from both sides. 4/3 control valve; lever control, spring return. 6/3 control valve Shut-off valve (e.g. ball valve). stop valves. Pressure limiting valve. The valve opens a flow path to the tank or to air when the valve inlet pressure exceeds the closing pressure. (Hydraulic left, pneumatic right). Pressure reducing valve, no pressure release. When the inlet pressure changes, the outlet pressure remains the same. But the inlet pressure by reduction must be higher than the outlet pressure.

Hydraulic motors - designation on hydraulic diagrams.

Pressure reducing and check valves, flow regulators - designation on hydraulic diagrams.

Filters, tanks, water separators and other elements on hydraulic diagrams.

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Check valve - purpose, device and principle of operation

Check valve purpose

The check valve is designed to freely pass the flow of the working fluid in one direction and block it in the opposite direction. The sealing element in these valves is a ball or cone valve that interacts with the seat so that there is no leakage of fluid.

The device of check valves is shown in (Fig. 1).

At the linear non-return valve (Fig. 1 a) in the body 1 having a hexagonal shape, the shutter 2, the spring 3, the support washer 4 and the retaining ring 5 are placed. promarmatura.ua/zatvory-diskovye from the seat and through the gap formed by the shutter and the edge of the bore in the body, and the radial drillings “B” and the central bore in the body of the shutter enters the outlet “B”. When fluid is supplied to the hole “B”, the flow is blocked.

Butt type non-return valve device (Fig. 1 b) the outlet valve is made at an angle of 90 degrees to the valve axis, and both connecting holes are brought out to the lower mounting plane.

The built-in valve (Fig. 1 c) contains a sleeve 1, a gate 2, a spring 3, an adapter sleeve 4 and a flange 5. The sleeve and sleeve are placed in a seat, which is made in the body part where the valve is to be built. Sealing on the outer surface of the sleeve and bushing is carried out with the help of rubber O-rings and protective washers made of plastic.

Check valve operation

The operation of the check valve is as follows, when fluid is supplied to the hole “A”, the valve gate rises above the seat, overcoming the force of the return spring. The fluid pressure drop across the valve depends on the fluid flow through it, and the pressure at which the valve opens, allowing the minimum flow through itself, depends only on the spring force and ranges from 0.05 to 0.3 MPa (from 0.5 to 3 kgf /cm2).

	Working line.
	control line.
	Drain line.
	Flexible line.
	Electric wire.
	Inside the interrupted line, the instruments are built in one unit.
	Shaft, lever, rod, piston rod.
	Connection of lines.
	Crossing lines.
	Direction of oil flow in the hydraulic circuit.
	Direction of air flow in a pneumatic circuit.
	Direction.
	Direction of rotation.
	Direction of flow in the valve. The perpendicular shows the lateral movement of the arrow.
	Adjustment indication.
	Spring.
	Adjustable spring.

Pumps and compressors.

designation on hydraulic diagrams.

Pressure management.

Pressure controls.

Designation of various types of valves that control pressure in hydraulics on hydraulic diagrams. Designation of hydraulic motors.

Valves.

Designation of valves on hydraulic diagrams.

	The valve is indicated by a square or series of squares when each the square indicates one operating position of the valve.
Directional control valves (e.g. boom control)
	The lines are connected to the square of the neutral position. Valve hole markings: P = pressure from the pump T - to the tank A, B, C ... - working lines Х,YZ... - control pressure a,b.c... - electrical control connections
	One way to flow.
	Two paths for flow.
	One path for flow, two connections closed.
	Two paths for flow, one connection closed.
In the following examples, the first digit indicates the number of connections. Second the number indicates the number of working positions.
	3/2 control valve; control by pressure from both sides.
	4/3 control valve; lever control, return spring.
	6/3 control valve
	Shut-off valve (e.g. ball valve).
stop valves.
	Pressure limiting valve. The valve opens the flow channel to the tank or to the air, when the valve inlet pressure exceeds the closing pressure. (Hydraulic left, pneumatic right).
	Pressure reducing valve, no pressure release. When the inlet pressure changes, the outlet pressure remains former. But the inlet pressure by reduction must be above outlet pressure

Hydraulic motors - designation on hydraulic diagrams.

Pressure reducing and check valves, flow regulators - designation on hydraulic diagrams.

Filters, tanks, water separators and other elements on hydraulic diagrams.

The hydraulic diagram is an element of technical documentation, which, using symbols, shows information about the elements of the hydraulic system, and the relationship between them.

According to the ESKD standards, hydraulic circuits are designated in the main inscription cipher with the letter "G" (- the letter "P").

As can be seen from the definition, hydraulic scheme conditionally shows the elements that are interconnected by pipelines - designated lines. Therefore, in order to correctly read the hydraulic circuit, you need to know how this or that element is indicated on the diagram. Symbols for elements are indicated in GOST 2.781-96. Study this document and you will be able to find out how the main elements of hydraulics are indicated.

Designations of hydraulic elements on the diagrams

Consider the main elements hydraulic circuits.

Pipelines

The pipelines on the hydraulic diagrams are shown with solid lines connecting the elements. Control lines are usually shown as a dotted line. The directions of fluid movement, if necessary, can be indicated by arrows. Often on hydraulic diagrams they indicate lines - a letter P denotes the pressure line, T - drain, X - control, l - drainage.

The connection of lines is shown with a dot, and if the lines intersect in the diagram, but are not connected, the intersection point is indicated by an arc.

Tank

The tank in hydraulics is an important element that is the storage of hydraulic fluid. A tank connected to the atmosphere is shown on the hydraulic diagram as follows.

A closed tank or container, such as a hydraulic accumulator, is shown as a closed loop.

Shown below hydraulic drive diagram, allowing you to move the rod of the hydraulic cylinder, with the possibility of charging the accumulator.

Hot and cold water pipelines, drains, sewer systems, gas supply networks, ventilation and air conditioning systems, as well as heating systems are sanitary systems and engineering equipment of residential, industrial and public buildings.

In order to equip buildings for various purposes with engineering and sanitary systems, a set of working drawings is developed and compiled. It includes:

Plans and sections of installations

Plans, sections and axonometric diagrams of systems

General data of water supply, heating, sewerage, ventilation and air conditioning systems

The main components of engineering and sanitary systems are:

Pipelines (risers, horizontal lines and connections to devices)

Pipe fittings (valves, cocks, gate valves, valves, etc.)

Various equipment (pumps, filters, air conditioners, water heaters, etc.)

The basis for drawing up drawings of engineering and sanitary systems of buildings and structures is the information that is contained in the architectural and construction drawings, on the sections and plans on them. It contains graphic images and layouts of pipelines and pipeline fittings, as well as developments, profiles and sections of walls, which depict both the elements of engineering and sanitary systems themselves, and the connections that should be between them. For a more visual and understandable image of the most complex nodes, some fragments of sections and plans are made on a larger scale.

The axonometric diagrams, made in frontal isometry, depict the most complex in their design and the most extensive networks of plumbing, heating systems and gas supply systems. At the same time, for individual sections of pipelines, the values \u200b\u200bof such quantities as the diameter, direction and length of the slope, as well as the length of the section, are indicated. Specifications of equipment and materials are attached to the working drawings.

According to accepted standards, conventional graphic symbols are used to depict various elements of sanitary systems in diagrams and drawings. Special tables contain the designations that should be used to depict both the pipelines themselves and the fittings used in them on axonometric diagrams, developments, sections and plans of engineering and sanitary systems of buildings.

According to GOST 21.601 - 79, a solid main line is used to draw conditional graphic elements of pipeline systems, and those parts that are invisible (in channels, underground) - a dashed line of the same thickness. A thin solid line is used to depict technological equipment and building structures.

If it is necessary to draw the dimensions of the conventional signs of pipeline fittings (gate valves, valves, etc.), then their dimensions are taken equal to 3-3.5 pipe diameters. Elements of networks and sanitary systems are supplied with special brands (alphanumeric designations).

The table below shows the conditional graphic elements of pipelines GOST 2.784 - 96.

Piping elements

Designation	Name
	Pipe line suction, pressure, drain
	Piping of the control line, drainage, air outlet, condensate drainage
	Piping connection
	Crossing pipelines without connection
	Connection point for power take-off or measuring device (closed)
	Connection point for power take-off or measuring device (connected)
	Pipeline with vertical riser
	Flexible pipeline, hose
	Isolated pipeline section
	Pipeline in a pipe (case)
	Pipeline in stuffing box
	Detachable piping connection
	flange connection
	Union threaded connection
	Union threaded connection
	Sleeve elastic connection
	Swivel joint single-line
	Swivel joint three-way
	Pipe end for detachable connection
	Flanged end
	Union threaded end
	Coupling threaded end
	Sleeve elastic
	The end of the pipeline with a plug (plug)
	Flanged pipe end with plug
	Threaded pipe end with plug

	Tee
	cross
	Branch (elbow)
	Splitter, collector, comb
	Siphon (water seal)
	Transition, adapter pipe
	Transition flange
	Union transition
	Quick coupling without locking element (connected or disconnected)
	Quick coupling with locking element (connected and disconnected)
	Compensator
	Compensator U-shaped
	Lyre-shaped compensator
	Lens compensator
	Wavy compensator
	Compensator Z-shaped
	Bellows expansion joint
	Ring compensator
	Telescopic compensator

	Shock-absorbing insert
	Soundproof insert
	Electrical insulating insert
	Place of resistance with a flow rate dependent on the viscosity of the working medium
	Place of resistance with a flow rate that does not depend on the viscosity of the working medium (throttle washer, restrictive flow meter, diaphragm)
	Fixed pipeline support
	Movable support (general designation)
	Ball bearing
	support guide
	sliding support
	roller support
	elastic support
	Suspension fixed
	suspension guide
	Suspension elastic
	Water hammer absorber
	Breakthrough membrane
	Nozzle
	Atmospheric air intake
	Engine air intake
	Connecting device to other systems (testing machines, washing machines, air conditioners, etc.)
	Lubrication point
	Splash lubrication point
	Drip lubrication
	Grease nozzle