Calibration of measuring equipment BRL 100: everything you need to know

When an auditor from your certification body asks you: "When was this manifold last calibrated?" — and your answer is "no idea", you have a finding on your hands. Calibration of measuring equipment is one of the most-checked elements in a BRL 100 audit, and at the same time one of the elements that installation companies most often register incorrectly.

This article explains which instruments need to be calibrated, how often, who is allowed to do it, and how to get your records in order — so that at the next audit you can put the calibration certificate on the table in three clicks.

Why BRL 100 sets calibration requirements

BRL 100 (the assessment guideline for the installation and maintenance of refrigeration installations and heat pumps, issued by one of six authorised certification bodies — InstallQ is not one of them, see what is BRL 100?) requires that the measuring equipment you use for safety- and leakage-related work is traceably accurate. That is not a bureaucratic requirement for the sake of form.

When you carry out a leak check on an installation that is above the 5-tonne CO₂-eq threshold (see also what is BRL 100?), the measurement you take needs to be reliable. A leak detector that hasn't been calibrated for years can give false positive or false negative results. A manifold set with a calibrated pressure needle gives you certainty that the figures on the work order are correct — and that counts with a customer, with an insurance company, and with an auditor.

The same applies to refrigerant scales: if you top up 2.0 kg of R-32 but the scale reads 0.3 kg high, your refrigerant balance will be structurally wrong. That is an immediate finding at the BRL 100 audit.

Which instruments need to be calibrated?

BRL 100 does not name an exhaustive list of brands or models, but the functional categories are clear. These are the instrument types that are checked as standard at an audit:

1. Manifold sets (pressure gauges)

The pressure gauges — high-side and low-side — that you use for filling, evacuating and carrying out leak checks. Manifolds are exposed to high pressures, vibrations from driving in the van, and temperature changes. Needle deviations of 0.5–1.0 bar after a year of intensive use are not exceptional.

2. Electronic leak detectors

Handheld detectors (infrared, heated semiconductor, ultrasonic) that detect F-gases. The sensor cell degrades over time; a detector that could once detect 5 grams per year may, after two years of intensive use, only manage 20 grams per year. BRL 100 and STEK require that you can demonstrate that the detector was sensitive enough at the moment of use.

3. Refrigerant scales

Both the scales you use for topping up (cylinder scales for recovery and addition) and the hand scales for cylinder checks. Scales in the van are subjected to daily shocks; deviations of 50–200 grams occur regularly in uncalibrated examples.

4. Thermometers / temperature clamp meters

Contactless and clamp thermometers that you use for superheat and subcooling measurements. Relevant for the accuracy of pressure-temperature readings and work order documentation.

5. Vacuum gauges

An incorrect vacuum measurement can lead to an inadequately evacuated installation — with condensation problems and an increased risk of leakage as a result. Especially relevant for heat pump installations.

6. Recovery equipment (recovery units)

To a lesser extent than measuring instruments, but STEK checks also look at whether the recovery equipment is suitable and certified for the type of refrigerants you work with.

How often does calibration need to happen?

BRL 100 does not prescribe a universal calibration interval in days or months, but sets the requirement of traceable accuracy combined with the principle of risk-based management. In practice, however, auditors and certification bodies apply the following rules of thumb, which are broadly regarded as the norm in the sector:

| Instrument | Usual interval | |---|---| | Manifold set (pressure gauges) | 12 months | | Electronic leak detector | 12 months | | Refrigerant scale | 12 months | | Thermometer / clamp meter | 12 months | | Vacuum gauge | 12–24 months |

Important: the interval starts on the date of the previous calibration — not on the date of purchase. If a manifold was calibrated in February 2025 and your audit is in January 2026, it is valid. If the calibration is from January 2025 and the audit is in February 2026: expired, finding.

Some manufacturers state shorter intervals in their manual — those then take precedence. A Testo 316-3 leak detector, for example, may recommend a sensor replacement after 2 years; if that date has passed, that counts as insufficient.

Who is allowed to calibrate?

This is the question that causes the most misunderstandings. The answer in one sentence: an accredited calibration institute or the manufacturer itself, with a traceable certificate as proof.

### Accreditation via the RvA

In the Netherlands, the Raad voor Accreditatie (RvA) is the body that accredits calibration laboratories. A calibration by an RvA-accredited laboratory gives you a certificate that:

• Identifies the instrument (serial number, make, type)
• States the measured deviation relative to a national or international measurement standard
• States the date of calibration
• Is signed by the calibration institute

That certificate is the document you show at an audit.

### Manufacturer calibration

Many manufacturers of leak detectors (Inficon, Testo, Bacharach, Ritchie/Yellow Jacket) offer a calibration service through their own service centre. As long as this service centre supplies a certificate of traceability that goes back to national measurement standards (NMi or equivalent), that is in most cases accepted at audit.

### What you CANNOT do

An "internal calibration" by your own technician — where you compare the instrument against another uncalibrated instrument — does not qualify. BRL 100 requires traceable calibration: the chain of measurement must go back to a recognised measurement standard. Comparing two uncalibrated manifolds against each other proves nothing.

Likewise: applying a calibration sticker without a certificate as proof is insufficient. The sticker is a memory aid, not the proof.

How do you keep your records up to date?

This is the practical side that goes wrong at many companies. You've had a correct calibration done, the certificate is somewhere, but at the audit you have to go looking for it. The five elements that need to be in your records per instrument:

1. Instrument ID — an internal number or the manufacturer's serial number 2. Make and type — so the auditor recognises the instrument 3. Date of last calibration — day/month/year 4. Valid until date — based on the calibration interval 5. Certificate or reference — a PDF scan of the calibration certificate

In Koldwerk's tool management module you store all this data per instrument. The system automatically gives a status alert as soon as a calibration expires within 30 days, and a dashboard widget shows all instruments whose calibration is due to expire soon. Expired tools cannot be issued via the issue module — that is not only convenient, it also prevents a technician from heading out in the van with an instrument that will produce an immediate finding at audit.

The tool management export is part of the BRL 100 audit package, so that at an audit you have a one-click overview of all instruments, their calibration status and the associated certificates.

Practical tips for daily practice

Don't calibrate all instruments at once. If you calibrate everything in December, all instruments will also expire together in December of the following year. You then either have a busy December with several instruments away for calibration at the same time, or you run the risk of having a gap right before an audit. Spread calibrations over the year.

Store the certificates digitally, immediately on receipt. A paper certificate that disappears into a drawer is one you'll have lost by audit time. Scan it and save it with the instrument in your records — or use the upload function in Koldwerk's tool management.

Schedule calibrations in your work planning. Treat a calibration job as a work order: customer = the calibration service, instrument = the object. That way it doesn't get lost in the day-to-day rush and you have a date attached to it.

Inform technicians about the status of their tools. A technician who heads out with an expired leak detector often doesn't know it. Make sure the tool or your work management system communicates the status — not only at the autumn audit.

When new tools come in, check whether a baseline calibration was included. New instruments are not automatically calibrated; the manufacturer sometimes only supplies a production test certificate, which is not the same as a calibration at your specified measurement point. Check this at the time of purchase.

What does calibration cost in practice?

A realistic overview of calibration costs at common service providers in the Netherlands (indicative, prices vary):

| Instrument | Indicative cost | |---|---| | Manifold set | €60–120 per set | | Electronic leak detector (sensor check) | €80–150 | | Refrigerant scale | €40–80 | | Thermometer / clamp | €40–70 |

For a company with 4 technicians, each with their own manifold set and leak detector, plus 2 shared scales: budget €600–900 per year in calibration costs. That is less than a single avoided audit finding with a repeat audit typically costs.

Conclusion

Calibration of measuring equipment is not an optional extra under BRL 100 — it is a structural part of your quality system. The key points at a glance:

• Calibrate manifolds, leak detectors, scales and thermometers at least annually
• Use an RvA-accredited calibration service or the manufacturer with a traceable certificate
• Store every certificate digitally, linked to the instrument's serial number
• Make sure an expired calibration produces a block in your work process, not a surprise at audit

Do you have your instruments in order but not yet your complete BRL 100 records? Then also read what is administratively needed for BRL 100 and see whether the tool management module can reduce your administrative burden.

Disclaimer: this article is an explanation based on the principles of BRL 100 and common sector practice. The official BRL 100 text takes precedence. Consult your certification body for the precise requirements that apply to your business situation.