Flue gas analyser calibration: intervals, sensor life and what the certificate shows

An analyser can drift without looking wrong: a tired CO cell still puts a plausible number on the screen. Kane's KANE458 manual notes that most sensors give a zero output when they fail, and that an out-of-calibration analyser can make the combustion reports you produce invalid. The annual calibration and its certificate are the check on both.

How often must a flue gas analyser be calibrated?

Once a year. Kane's KANE958 manual says every analyser and pressure meter should be recertified annually, and the KANE458 manual gives the reason: sensor life runs past five years, but the instrument is serviced and recertified every year to counter long-term sensor or electronics drift and accidental damage, and local regulations may ask for it more often. Testo recommends an annual check of the testo 300 by a Testo-authorised service centre to keep it inside its specified accuracy. TPI's 709R manual recommends calibration every 12 months, as written in BS 7967.

BS 7967:2015's published scope covers using an analyser conforming to BS EN 50379-3 or BS 7927, by an operative shown competent through the ACS assessments; the clause text is behind BSI's paywall. Worcester's Greenstar 4000 combi instructions likewise ask for an analyser conforming to BS 7967. The instruction that binds you is your own analyser's manual.

What does the calibration service cost?

From £85 to £219 a year before VAT on the prices the makers published on 2 October 2026, depending on the make and the instrument's age.

What happens at a calibration service?

The instrument is inspected, worn parts replaced and its readings adjusted against known gases, then it comes back with a certificate. Kane's KANE458 manual lists the fixed-price work: adjusting it to the original specification, parts and labour on the CO and CO₂/O₂ sensors, pump, battery, internal tubing, water trap and filters, and recertifying to national standards. Toxic cells, cases and probes are extra.

Anton lists inspection, test and recalibration, in-warranty parts, a traceable report and a two working day turnaround. Warranty rides on the service, and Kane's two manuals differ: the KANE958 says an annual return extends the warranty up to 10 years, the 2017 KANE458 manual says to 5 years. TPI's 709R guarantee runs 6 years subject to the annual service.

What does the certificate show, and who asks for it?

It identifies the instrument and confirms its performance against traceable standards on a date. Kane returns a fully traceable calibration certificate and keeps an electronic copy in your dashboard, Anton a traceable calibration report, and Testo supplies a calibration protocol with a new instrument. Check that the serial number on it matches the instrument in your hand.

Gas Safe Register inspectors ask: Registered Gas Engineer's inspection guide lists a fully charged analyser with an in-date calibration certificate among the kit to have with you. The KANE458 and KANE958 count down the days to the next calibration on screen, and TPI prints the serial number and next calibration due date on every 709R printout.

How long do the sensors last, and what are the signs of failure?

Five to six years on the published figures: more than five for the KANE458's CO and CO₂ sensors, up to 72 months for the testo 300's. Water shortens that. The KANE958 manual warns that an analyser left cold in a van overnight can form condensation in a warm room, the O₂ or CO₂ reading then shows as a dash, and sensors may be permanently damaged.

Other signs: a KANE458 that will not complete its fresh air auto calibration needs its sensors replaced or recalibrated by an authorised repair centre, and a testo 300 sensor diagnosis of not OK is a prompt, since Testo says a sensor can recover.

Can you check the analyser yourself between calibrations?

You can check it responds, not that it is accurate. The fresh air zero runs 60 seconds on a KANE958, 60 to 90 on a KANE458 and 30 on a testo 300; after the KANE458's purge, Kane expects CO at zero and oxygen at 20.9% ± 0.3%. A bump test, in Kane's words, briefly exposes the instrument to a known gas to show it works within limits; a calibration adjusts the settled reading to that gas. Neither produces a certificate.

Keep the make, model, serial number and certificate expiry somewhere other than the instrument. Manifold's FlueScan reads CO, CO₂ and the ratio off the analyser screen with the phone camera for you to confirm, and a photo of the current certificate can sit on the same check as the readings it stands behind.