Customer field test report form for water and coolant readings

This form covers routine readings a customer takes between supplier visits on open recirculating cooling water and water-mix metalworking fluids. It does not set control ranges, replace laboratory analysis or depletion analysis, or cover boiler water, drinking water, Legionella sampling or high-purity water below about 5 µS/cm.

When should a customer use a site readings form for water and coolant?

A customer site readings form is the right tool when plant staff take routine readings on a cooling water system or a metalworking fluid sump between supplier visits and the supplier has to judge those readings without being on site. The form gives every reading the same fields, so a value taken by a night-shift operator can be compared with one taken by the supplier's engineer three weeks later. Typical users are maintenance technicians, machine shop leads and utilities operators who check a cooling tower basin or a central coolant system once a shift, once a day or once a week.

Fluid management guidance asks for this kind of record. The OSHA metalworking fluids best practices manual says a fluid testing procedure should state where and when to collect samples, how to treat them, which tests to run, the protocol for each test and the name of the person who records the results (OSHA metalworking fluids manual). For cooling towers, the US Department of Energy Federal Energy Management Program advises sites to "Keep a log of make-up and blowdown quantities, conductivity, and cycles of concentration" (US DOE FEMP, BMP 10).

Use the form when the treatment program already defines the control range for each reading. Do not use it to decide what the range should be; that decision belongs to the treatment program agreed between the customer and the supplier. The editable form and log are at the end of this page.

Which readings should a customer record for cooling water and coolant?

A customer readings form for cooling water and coolant records the site, system and sample point, the date and time, sample temperature, pH, conductivity, coolant concentration, the inhibitor or biocide residual the treatment program names, make-up and blowdown meter readings, the operator and remarks. The table below previews every field in the Word form and the Excel log; the example values are illustrative and are not targets.

The coolant concentration row is the one most often misread: the refractometer shows a scale reading, and for some metalworking fluids that reading is multiplied by a product-specific refractometer factor to give the actual concentration (Blaser Swisslube, n.d.). A cooling-water-only site leaves the coolant rows blank, and a machine shop without a cooling tower leaves the meter rows blank. The Word form prints these fields as one block per sample point, with the agreed control range in a column beside each reading, and the Excel log holds the same fields as columns so that each check becomes one row and trends show without retyping.

The Word form has six sections, previewed below.

The Excel log has four sheets: Instructions, Control ranges, Readings and Example. The Readings sheet holds the columns in the table above, one row per sample point per check, and the CSV file has the same header.

How should a customer record units, sample point and test method?

A customer should record the unit, the sample point and the test method next to every reading, because a number without them cannot be compared with the supplier's own measurements or with the last visit. Three habits make most of the difference.

First, write the unit the instrument reports and the reference temperature for conductivity. Specific conductance is reported in microsiemens per centimeter at 25 °C, and most modern meters correct a reading taken at another temperature to 25 °C automatically (USGS, 2019). A reading written as "1850" with no unit could be µS/cm, mS/m or a total dissolved solids estimate, and those differ by large factors.

Second, name the sample point and keep it fixed. Water in a cooling tower basin, a return line and a heat exchanger outlet can read differently, and coolant at the machine sump differs from coolant in the central tank. The OSHA metalworking fluids manual lists where and when to collect samples as the first item of a fluid testing procedure (OSHA metalworking fluids manual).

Third, record the method and instrument. ASTM D1293-18 separates Test Method A, precise laboratory measurement, from Test Method B, routine or continuous measurement, and both use a glass electrode (ASTM D1293-18). A pH strip is a different method and the form should say so. Use the terms in ASTM E2523-23, the terminology standard for metalworking fluid management, when naming fluid types and tests, so that customer and supplier mean the same thing (ASTM E2523-23).

How do you fill in the customer site readings form step by step?

A customer fills in the site readings form in six steps, one line per sample point per check, using the blank form or the Excel log.

1. Before first use, copy each agreed control range from the treatment program into the form header, with its unit and agreement date.

2. Calibrate or check the instruments as their makers instruct, and write the meter ID. USGS asks field staff to record calibration information in a meter logbook before and during field work (USGS, 2021).

3. Take the sample at the named point, let lines run until the water is representative, and measure pH and temperature at once. For any reagent or buffer, read its safety data sheet (SDS) first; the USGS pH chapter asks staff to keep SDS readily available for buffers and other chemicals (USGS, 2021).

4. Measure conductivity with temperature compensation on, then coolant concentration with a zeroed refractometer and the factor from the fluid maker's data sheet.

5. Read the make-up and blowdown totalizers on the same visit and write both, even if one looks wrong.

6. Mark any value outside the agreed range, write what you did in Remarks, and send the sheet to the supplier as the program asks.

Do not change dosing on one reading unless the treatment program says so. HSE guidance for metalworking fluids says not to add biocide until all good practice measures for concentration, pH, tramp oil content, metal contamination, operating temperature, agitation and flow have been followed (HSE MW5, 2021).

How do you read out-of-range values on a customer readings form?

An out-of-range value on a customer readings form is first a question about the reading and then a question about the system: check the sample point, method, temperature and instrument before treating the value as a change in the water or the coolant. The table below decides the first action for readings outside the control range the customer and supplier agreed; it sets no thresholds of its own.

The key row for cooling water is high conductivity: the US DOE advises checking that the ratio of make-up to blowdown flow and the ratio of blowdown to make-up conductivity both match the target cycles of concentration, and looking for leaks or other draw-off when they do not (US DOE FEMP, BMP 10). For coolant, the key row is low concentration, because a missing or wrong refractometer factor can produce it with no change in the sump. Write the action taken in Remarks on the same line, so the next reading shows whether it worked.

What does each reading on a customer form tell the supplier, and what not?

Each reading on a customer form tells the supplier one thing about the system at one point and one time, and none of them alone says why the system changed. pH tells the supplier whether the water or coolant has moved toward a scaling, corrosive or biologically active condition, since ASTM D1293-18 describes pH as a critical parameter for the ability of water to form scale or cause metallic corrosion (ASTM D1293-18). pH does not identify the cause.

Conductivity tells the supplier how concentrated the dissolved ions are. ASTM D1125-23 lists cooling water among the waters its methods apply to and describes them as useful for impurity detection (ASTM D1125-23). Conductivity does not name the ions, so it cannot separate hardness from chloride or from treatment chemicals.

Refractometer concentration tells the supplier roughly how much fluid is in the mix. Master Fluid Solutions notes that refractometers tend to read higher than the actual concentration over time because tramp oil and other contaminants also refract light, and that concentration by titration tends to read lower (Master Fluid Solutions, 2026). A refractometer reading says nothing about which components are depleted; the same bulletin describes laboratory depletion analysis for that.

Meter readings tell the supplier how much water entered and left the tower, which lets the supplier check the conductivity ratio. Appearance and remarks give context no instrument records. Together the readings show a trend; a single line on its own supports a question, not a conclusion.

How well do customer test kit readings match lab results for water and coolant?

Customer test kit readings match laboratory results for water and coolant only as far as the sample, the temperature and the method allow, and some readings change between the site and the laboratory. pH is the clearest case. The USGS pH chapter states: "The pH of a water sample can change substantially within hours or even minutes after sample collection as a result of temperature change; changes in concentrations of gases (carbon dioxide, hydrogen sulfide, ammonia); changes in redox conditions; mineral precipitation; metabolic respiration by microorganisms; and other chemical reactions, physical changes, and biological activity" (USGS, 2021). A laboratory pH on a bottle that travelled for two days is a different measurement from the operator's reading at the basin.

Conductivity holds up better if temperature compensation is right. USGS gives temperature compensation as typically accurate to ±5 percent for water from 5 to 35 °C with pH between 4 and 11, with larger errors in low-pH water (USGS, 2019). ISO 5667-3:2024 sets requirements for preserving, transporting and storing water samples and is particularly appropriate when samples cannot be analysed on site (ISO 5667-3:2024).

Coolant concentration depends on the method: refractometer, alkaline titration and acid split can give different numbers for the same used fluid (Master Fluid Solutions, 2026). When a customer value and a laboratory value differ, the form's method, time and temperature fields show whether the difference is in the system or in the measurement.

When is a customer reading not good enough to act on?

A customer reading is not good enough to act on when the form cannot show what was measured, where, when and how, or when the method is outside its range. Five cases cover most of the problem lines suppliers see.

The unit or sample point is missing, so the value cannot be compared with any earlier line. The temperature is missing on a pH or conductivity reading; USGS asks staff to record temperature with each pH measurement because temperature affects meters, electrodes and buffers (USGS, 2021). The pH was measured in very pure water: ASTM D1293-18 states that neither of its test methods is considered adequate for water whose conductivity is less than about 5 µS/cm (ASTM D1293-18). ISO 10523:2008 likewise limits its pH method to pH 2 to 12 and 0 to 50 °C (ISO 10523:2008).

The refractometer reading was written without the factor, or the scale looked diffuse; Blaser Swisslube notes that a diffuse reading means the emulsion is unstable or heavily loaded with tramp oil (Blaser Swisslube, n.d.). The reading was transcribed later from memory, with no measured time.

In each case the right action is a recheck, not a dosing change. Mark the line as "recheck", keep the original value on the form, and add the new reading as a new line with its own time. Deleting the first value hides the evidence a supplier needs to tell an instrument fault from a real change.

What should a customer send back with the site readings form?

A customer should send back the completed lines, the control ranges they were checked against, and the evidence behind any out-of-range value. That means the form or log itself with every field filled, the meter IDs and last calibration dates, photos of anything unusual such as foam, deposits or a diffuse refractometer line, and a short note of what the operator did on the day. If a laboratory sample was taken, send the bottle label and the time it left the site, since ISO 5667-3:2024 treats preservation, transport and storage as part of the sample (ISO 5667-3:2024).

Keep the original sheets. HSE guidance for water-mix metalworking fluids says to keep records of all tests for at least five years and to keep them in a table or graph that makes trends easy to spot (HSE MW5, 2021); the site's own program may set a different period. If a third party takes the readings, HSE says to review the results and remedial actions yourself (HSE MW5, 2021).

Send readings in a format the supplier can import. The Excel log comes with a CSV file of the same columns, because many record systems accept CSV but not spreadsheet files. In Lubinpla, a field care site data request lets a customer contact submit values, and the values the supplier approves become project records. Whatever system receives them, the supplier still decides what the readings mean against the agreed treatment program.

Key takeaways

• Record every reading with its unit, sample point, time, temperature and method; without them the value cannot be compared.

• Control ranges come from the treatment program, not from the form.

• Measure pH on site; it can change within hours of sampling.

• Write the refractometer scale reading and the factor, not only the result.

• Recheck before acting, and keep the first value on the sheet.