What does ppm measurement mean. We fight with quality. Coefficient of various instruments

The idea of ​​writing this article arose by chance, when a device that measures the degree of water pollution appeared in the company where I work. The device became so popular among the team that everything that has a liquid state was measured.

After a series of such measurements, I decided in more detail, in a calm atmosphere, to conduct “tests” of the water that I have to drink at home. After all, it's not a secret for anyone that water makes up almost 2/3 of a person's body weight, and our health depends on what kind of water we use.

The device, which will be discussed today, refers to TDS meters. Chinese manufacturers have long copied all possible technologies, and I suppose that you can find a Chinese analogue of any device on the Russian market.

In appearance, nondescript, similar to an electronic thermometer, the TDS device is designed to measure the salinity of water. Speaking in a simple and accessible language for the layman, this device measures the salt content in water.

Detailed characteristics of the device are presented in the summary table:

No matter how unfamiliar the characteristics of TDS are full of unfamiliar words, all that is needed to test the water is the numbers on the built-in screen.

I am sure that most of our readers have filters like "Barrier", "Aquaphor" or reverse osmosis at home. How they purify water, and whether purified water is available for drinking, is of interest to many. In today's article, we will look at how the Barrier filter cleans water. In addition, specially for this article, bottles of drinking water of various brands were purchased in one of the stores in Samara, and they will also pass our “test”.

Immediately I would like to dot all the "i".

The first test was ordinary tap water. The house, in which the internal water pipes have not been changed for 24 years, obviously contains if not a “bacteriological weapon”, then there is plenty of sand and salt in them.

As you can see, if you compare the result with the table of water pollution, then tap water is almost on the verge of acceptable values. I think no one will risk drinking such water without passing it through a filter.

The filter is a separate issue. I am sure that many, having bought a household filter, for the first months clearly followed the schedule for changing the cleaning cartridge, but then changed it from case to case.

I am no exception, there was a time when the cartridge worked beyond the recommended time for another couple of three months. What we drank, and what settled in our kidneys, the years will show. This time, too, the first tests of the Barrier filter were carried out on a filter that should have been replaced a month ago.

Terrible! Water that has been purified by the Barrier with an expired cartridge is much worse than tap water! I think now many are thinking about when was the last time I had a cartridge in the filter. The instructive numbers were a step towards the fact that the replacement cassette was replaced with a new one and a date for its next replacement was set. I am sure that now, after such indications, the replacement of the cartridge will be carried out on time.

To be honest, the numbers that the salt meter showed amazed me. Considering that the little daughter drank this water, one can only hope that this will not affect her health.

The next water measurement was made with a new cartridge already installed. The result, although on the verge, is in the range of pure water, which has been cleaned in a household filter.

Everyone knows that after installing a new cartridge, it is necessary to drain two jugs of water. We measured every water drain and the numbers were consistent.

Analyzing the obtained data, it should be understood that therapeutic mineral waters used according to a special recipe significantly exceed the permissible values ​​of water mineralization.

* - now I personally, under equal conditions, will choose this brand of water.

For those who find it difficult to translate ppm units into understandable values, let me remind you that 1 ppm corresponds to 1 mg / liter.

If I understood everything correctly and measured it, taking into account that the device is working (not a fact), then the water of most manufacturers does not reach the minimum limit of the mineralization indicator declared on the label.

What kind of water to buy and drink is your choice, but I would like every home to have a similar device that could detect indicators of water pollution in time. Agree, it would be useful to check the water from under the household filter once a week. Perhaps the water consumption in your family is much higher than the calculated one, and at the end of its life the cartridge no longer filtered, but exuded salt.

How much does a TDS salt meter cost? At first glance, the price range for this device can not even be determined. However, after a little monitoring of online stores, an almost twofold difference in price was revealed on different sites. The price ranges from 600 to 1350 rubles.

For everyone who wants to buy this device, we have found perhaps the cheapest price for the TDS device. The DC.com online store offers a range of salt meters, and prices start at $11.40. Translating this amount into a price understandable to Russians, it turns out a little more than 350 rubles.

When ordering a product in the online store, remember that you will have to pay for shipping.

So our test of the Barrier filter and a range of mineral and drinking water has come to an end. I am convinced that professionals working in laboratories will consider this "test" as amateurish. Although the numbers obtained as a result of the test are relative, the main thing is that it became clear to everyone that you need to change cartridges in household filters more often!

The article would not be complete if, after analyzing 7 brands of drinking water for mineralization, we would not tell which of the presented waters is cheaper. Our website frequently publishes price analysis data for consumer goods and products. Now it's time for drinking water.

• PPMv(parts per million by volume) is the unit of concentration in parts per million by volume. Those. the ratio of a volume fraction to everything (including that fraction). Naturally, for small concentrations, this value is equal to the ratio of the volume fraction to everything else, without taking into account this fraction.
• ! is the ratio of the partial pressure of water vapor in the gas mixture to the pressure of the dry mixture. For measurements of small values ​​of humidity in gases, this is the most common unit and in 99% of cases it is meant by the mysterious abbreviation PPM(=ppm).

• PPMw(parts per million by weight) is the unit of concentration in ppm by weight(sometimes say "by weight"). Those. the ratio of mass fraction to everything (including this fraction). Naturally, for small values ​​of concentration, this value is equal to the ratio of the weight fraction to everything else without taking into account this fraction.
  • lim x→0 (x/(1-x):1/x)=1, i.e. at x→0 the ratio x/(1-x) → x;
• ! In relation to humidity, this is the ratio of the mass of water vapor in a gas mixture to the mass of a dry gas mixture.

• Similarly: PPB (parts per billion) is a unit of concentration in parts per billion = parts per billion. Think there :)

How to convert ppm to mg/l?

• For solutions of something in there in water at 1 ppm w = 1 mg/l
• For all other cases, keep in mind that mg- this is a l- . Carefully cross the hedgehog and snake there!
• Above is all the necessary data for translation :)

Note that in most cases, the undefined unit "PPM" - for gas mixtures is PPMv, and for solutions and dry mixtures it is PPMw, although there is often a desire to bruise the author of the text, who used such a unit for fractional estimates without reservation. Be careful, because with a definition error, you may not even get into an order of magnitude.

The defectiveness of products is expressed equally often both as a percentage and in relation to a million samples produced. You can argue about the pros and cons of this or that way of expression for a long time. In my practice, I most often use the expression of defectiveness in relation to a million samples and find it more convenient. However, the calculation methods discussed in this article can be easily transferred to percentages.

Product defectiveness is a characteristic that describes the number of defective samples in a batch or a certain number of samples produced. In this case, we will use the PPM (Parts Per Million) indicator - the number of defective samples in relation to a million manufactured.

PPM = Number of Defective Samples / Million Samples Manufactured

A figure of 2500 ppm means that out of a million manufactured items, 2500 may be defective.

The point is to determine how many defective samples we will receive in the manufacture of 1 million products. It should be noted that we are not talking about defects, but about defective samples. Those. the calculation takes into account not the number of defects, but the number of products containing at least one defect. Each defective sample can contain an unlimited number of defects, and yet it is the number of samples that counts.

To calculate the indicator, it is not at all necessary to wait for the moment when a million products will be produced. When calculating, any number of observed products can be accepted. In this case, the calculation formula will take the following form:

PPM = (number of defective samples / number of samples produced) 1,000,000

For example, 750 products were produced, 36 of which did not pass quality control - they turned out to be defective. In this way:

PPM = (36 / 750) 1,000,000 = 48,000

Using PPM to assess quality in sampling

When using a metric to account for the results of sampling, the question arises of whether to relate the number of defective samples found - to the sample size or lot size?

The number of defective samples found in the sample is compared with the estimated number, on the basis of which a conclusion is made about the suitability or unsuitability, acceptance or rejection of the entire batch. In the event that the batch is accepted based on the results of the control, the number of defects is compared with the number of products in the batch. If the batch is blocked, the number of defects is compared with the sample size. After sorting the batch, the total number of defective samples found is compared to the number of tested products. The calculation formulas are given below:

• For the received batch:
  PPM = (number of defective samples / lot size) 1,000,000
• For a rejected lot:
  PPM = (number of defective samples / sample size) 1,000,000
• For a batch of products after sorting:
  PPM = (number of defective samples / number of tested samples) 1,000,000

The last formula is also used for multilevel sampling. For example, a batch of 1000 samples was randomly tested. The sample size is 50 samples. Found 2 defective samples, which is within the tolerance for this case. The calculation is carried out as follows:

PPM = (2 / 1,000) 1,000,000 = 2,000 ppm

If the batch was rejected (2 defective samples out of 50 - not acceptable), the calculation is carried out as follows:

PPM = (2 / 50) 1,000,000 = 40,000 ppm

The rejected lot was 100% tested, resulting in another 37 defective items. So the final result looks like this:

PPM = [(2 + 37) / 1,000] 1,000,000 = 39,000 ppm

Instead of the PPM indicator, DPM (Defects Per Million) is sometimes used - the number of defects per million products. Although both indicators may represent the same value - the number of defective samples in a million products - they should be distinguished and used for different purposes. DPM, as an indicator of the number of defects in a million samples, is certainly less used than PPM, but it can tell a lot more about the process.

Once, about 10-12 years ago, I don’t remember exactly, on the pages of some central quality magazine there was such an idea that allegedly one quality director of some plant, when asked by some inspectors, how quality work is organized at your factory, answered "We fight with quality." Say, he made a reservation, in fact he wanted to say that they are fighting for quality, and not with quality, but you and I know that this is not a reservation, that he is, they say, an illiterate quality director. That's the idea in that article.

I think that in some companies today they really struggle with quality. Now, when inspectors come to us and ask how you are doing with quality, I answer them - we are struggling with quality - and look at their reaction. They look at me, look at the customer ppm chart, which is all zeros, and we smile at each other. Something like that.

The first question to the director of quality. What is your ppm? First, do all QCs and CEOs know what ppm is? Second. There should be a counter-question to this question - please specify what ppm are you talking about - external or internal? Here I will not explain what ppm is, because we already speak the same language. If you don't know, don't read further, you still won't understand. In one of the interviews, one quality director, positioning himself as a highly literate quality director, proudly reports that his company's accepted customer ppm is 1200 something. Any specialist from the automotive industry will now understand me - who keeps such a director at work?

So, the organization should count its marriage in ppm. Now someone is skewed, not a marriage, but inappropriate products! Gentlemen are good! Who told you that you have to say inappropriate products? You don't even know. It's like asking stupid students what the difference is between a CEO and a director. What is the difference between marriage and nonconforming products? I already forgot about it even to remember how a new employee came to our company, who had previously worked in a terry Soviet company, and there he heard that it was necessary to say inappropriate products. And we work in an international company and we speak Russian in marriage, we speak English in scrap, we speak Russian in a marriage isolator, in English we speak segregation area.

What is more important, to say non-conforming products and at the same time not know what ppm is and consider non-conforming products as a percentage, or to say marriage, and have an annual goal of 5 customer ppm, but in fact 0?

I can responsibly state that systematic work on the quality of products is carried out at the enterprises of the automotive industry. In all sectors of the economy, the international standard for the quality management system ISO 9001 is applied. It is good. But why then are enterprises that have a quality management system certified in accordance with this standard most often a swamp? Without going into deep details, the answer is that certification bodies, even with international accreditation, do not conduct a deep check of the functioning of the system, there are answers to their checklists - good, no - well, okay. We need clients! And also the ISO 9001 standard itself is weak. His demands, if someone is too tough, it really is a swamp. ISO/TS 16949 is widely used in the automotive industry. I won't go into detail here on how many points it differs from ISO 9001. What lies on the surface is that quality management system certification is carried out by international certification bodies accredited by IATF, among them there are no Russian certification bodies. This is the first. Second, in order to be certified to this standard (or someone will say that this is not a standard, this is a specification), I say the standard, the organization must also fulfill customer specific requirements. Those. the standard itself is many times more complicated than ISO 9001, plus meet the specific requirements of consumers, the implementation of which will be verified by the auditor of the certification body. For example, ISO/TS says that internal auditors must be trained (read ISO/TS Internal Auditor Certifications). Without this, you will not pass the certification. And if the organization is, for example, a Ford tier 1 supplier, then internal auditors, in addition, must be trained in APQP, PPAP, FMEA, SPC, MSA. More difficult? Plus, back in the auto industry, OEMs themselves love to audit their tier 1 suppliers to their own standards. Failure to pass an audit is a loss of business. For example, the Renault-Nissan-AVTOVAZ alliance has an ASES supplier evaluation standard and, based on the results of the audit, assigns the supplier an A, B, C or D rank. D - business loss or this is a new supplier, if it is promising, it will be developed, C - it is possible to supply , but corrective actions are required, B - well done, A - unique. Even more interesting?

Plus, many car assembly suppliers are Western companies with a Western production culture. These companies usually have their own corporate requirements for production systems, which are even more stringent than ISO/TS 16949. Audits are usually carried out by the central office of a western company once a year. The result obtained is the personal result of the plant director. Those. the first person of the enterprise wants to have a high production culture.

I agree that the production culture of most domestic enterprises is indeed very low. And only the introduction of modern tools, namely through the knee, will gradually change the situation. Nothing will change right away; in order to build a more or less stable system, it takes about a year and a half or two. In Russia, traditionally poor command of the English language. People can't interview and get a job in a western company because they don't speak English. Many modern instruments are in English. Western companies do not keep translators - all managers speak English.

So what are these tools?

ISO/TS 16949 standard.

Methods APQP, PPAP, FMEA, SPC, MSA.

In MMOG/LE logistics, implementation of the FIFO principle

Pareto tools, 8D, Ishikawa chart for causes and non-detection, 5 whys.

6 sigma, Lean, TPM, 5S, visual management.

OEM requirements for suppliers, such as ASES.

A frequent requirement is the ISO 14001 standard. Sometimes also OHSAS 18001.

In terms of labor protection - Green cross, top safety visits, near miss.

Plus own western enterprise standard for quality system (in addition to ISO/TS and OEM standard).

And always one thing - cleanliness in production!

And finally - what is a quality product? I will say with confidence - if it is 100% consistent with the design documentation (drawing). You can argue here that the design documentation itself can be bad - what is important for us - the drawing was agreed upon by the consumer, does he expect products from us according to this drawing? Then do according to the drawing! And then it will be of high quality for the consumer! If each unit of production is according to the drawing, there will be no marriage. Customer ppm will be 0! Well, provide it!

And then the products will be according to the drawing, if the technologist draws up competent operating instructions with pictures, what and where to press the operator, and the operator will 100% follow these instructions. And for this, the technologists of the operator will train, examine, assign him a rank, periodically check. And in order for the equipment to produce quality products, the appropriate specialists must regularly maintain it and regularly check its parameters, since they form the parameters of the product. And the quality service will carry out incoming control of the purchased raw materials and components, does everything correspond to the same design documentation? And during the process, it will check the conformity of the products, and if a discrepancy is revealed, it will block the batch produced since the previous positive check. And the procurement manager initiates the assessment of suppliers through audits, where his quality system will be correctly assessed and, in case of insanity of the supplier, initiates his replacement. And the company's logisticians organize work in accordance with MMOG / LE and FIFO, and personnel officers (HRs) organize the identification of training needs and train employees in the necessary tools, and accountants will calculate the cost of poor quality. And the HSE specialist organizes the deployment of a safety culture at the enterprise through the Green cross, top safety, near miss tools. And the IT specialist will organize a network drive, where the factory documentation will be organized by processes, and will back-up at regular intervals to avoid information loss. And the quality service, in addition to incoming, operational and acceptance control, will plan and conduct internal audits, initiate the development and implementation of corrective actions, open 8D in any case with quality, collect statistics on internal defects and monitor the implementation of measures. And the CEO, having received personal goals from the founder, competently sets personal measurable goals at the beginning of the year for each director-manager, his direct subordinate, and during the year conducts cuts by achievement status. And the quality director looks after all this, having a holistic view of the system, and then to the auditor's question - how is your quality? - will answer - we fight with quality!

(ppm). To convert from mS/cm to ppm and vice versa, you need to determine which conversion factor to use. Typically TDS meters use ratios of 0.5 , 0.64 or 0.7 . Less commonly used is 1.0. Sometimes the device has the function of manually entering this coefficient.

*Note: 1 mS/cm = 1000 μS/cm

Coefficient of various instruments

Manufacturer or device	Coefficient
,	0.5
	0.64
	0.70
	1.00

How to convert TDS units (ppm) to EC (mS/cm) yourself

To convert the EC unit ( µS/cm) in TDS (ppm) you need a value in µS/cm multiply on the coefficient of the TDS meter (0.5, 0.7 or other).

To convert from TDS (ppm) to EC ( µS/cm) it is necessary to divide the measured value by the coefficient of the TDS meter (0.5, 0.7 or other).

How to determine the conversion factor of a TDS meter

The conversion factor of a TDS meter can be determined if the instrument is also an EC meter. In such cases, for the same solution, it is necessary to measure the mineralization (ppm) and electrical conductivity (µS/cm) readings. Next, we divide the salinity value (ppm) by the electrical conductivity value (µS/cm). The resulting number is the conversion factor for that TDS meter.