looking after your flue gas analyser

Zeichen setzen für die Zukunft Zeichen setzen für die Zukunft Committing to the future Committing to the future

Looking after your Flue Gas Analyser

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Committing to the future

testo AG, Title (version), author, date, confidentiality

Domestic Flue Gas Analysers

• How to get the best out of your Testo portable combustion analyser

Most electronic portable combustion analysers

have eight common components:

•Probe

•Pump

•Condensate trap

•Particulate filter

•Gas Sensors (O2, CO)

•Power supply (batteries)

•Circuit board (PCB) including a display. Often with a

pressure sensor and differential temperature capabilities

as well as IR senders to link with printers or a PDA

• Printer

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• Flue Gas probe

The majority of flue gas probes incorporate a type ‘K’

thermocouple for the measurement of temperature.

They are designed so that the thermocouple end is

protected yet can still come into contact with the flue

gas.

For accurate measurement the thermocouple should

not touch the protective casing.

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The most common failure of thermocouples is due to

damaged probe tips.

Most common cause of “false” readings is due to the

incorrect alignment of the probe in the flue. Also

having the charger connected when making a

measurement.

Always test with a warm flue to allow the boiler to

settle at the highest level of CO2. Wait until the flue

temperature and CO2 are steady before you accept

the reading as true.

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Take good care of your Analyser

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• Filters

Filters are designed to remove particulate

matter from the flue gas sample before it enters

the pump and passes across the gas sensors.

It is important that the filters are changed

regularly, Particularly on oil boilers. If the filter

is wet replace with a dry one, and remove

droplets of condensation from the probe filter

housing with a tissue.

Check the particle filter of the flue gas

probe for contamination at regular

intervals: check visually by looking

through the window of the filter

chamber. Replace the filter if there are

signs of contamination.

Example of a dirty filter used on oil

against a clean filter

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Any reduction in the flue gas sample rate

results in a slow response from the gas

sensor. This comes from:

Blocked particulate filters

Pumps exposed to flue gas condensate

Condensate traps full of water

You can hear when the pump is labouring

or not working efficiently.

Pump

• Analyser pump

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• Emptying the condensate trap

It is important to ensure that condensate trap is emptied on a regular basis.

Failure to empty the condensate trap will result in

moisture being drawn through the instrument and

causing premature gas sensor failure.

There is a sight on the sides of the instrument to check

condensate levels.

It is good practice to empty the trap after each use

It is good practice NOT to leave your analyser with the

pump running and the probe in the flue, when not

observing readings. This unnecessarily pulls water

vapour in runs the battery down and exposes the

analyser to high CO if the boiler cycles off to on.

Despite built in protection against high CO,

incorporated in the 327 analyser. Damage can occur if

the displayed warning is ignored. Remove and Purge

in fresh air.

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Take good care of your analyser

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• Gas sensors

Gas sensors within portable combustion analysers normally fail due to their age

not the amount they are used i.e. the chemical reactions deplete in time rather

than the number of times the analyser is used.

• But, they can also fail due to exposure to moisture (flue gas condensate) and

exposure to high gas concentrations (CO)

• Low temperatures can lead to the impression of a failure as this effects the

chemical reaction within gas sensor.

• Do NOT leave your analyser in the cold over night, condensation will form and

can temporarily stop the sensors from calibrating.

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• ALWAYS remove condensate from the trap

before storage to prevent migration to gas

sensor membrane or pump

• DO NOT operate for long periods at high

concentrations (CO) as this will poison the

sensor

• During winter months keep equipment above

5°C. DO NOT store in vehicles overnight

• Excess Carbon Monoxide (>4,000ppm) sampled

by the analyser can damage the CO gas sensor.

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• Circuit board Circuit boards within analysers are robust in construction but are prone to damage if

they dropped or treated without care.

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• Printer The printer has a thermal printing

mechanism and as such is susceptible

to heat. If the printer is placed in a

particularly hot environment it may

effect the quality of the print.

Also, the printer mechanism requires

replacement print paper to be fed

carefully through the mechanism.

Do not force or pull paper through the

mechanism with excessive force.

The other common problem is with

printer batteries. Always use good

quality batteries, never leave them in

the printer for extended periods and

always make sure that they are fitted

correctly.

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• Power supplies / Batteries

The analyser must not be connected to the

charger when making measurements.

The measuring instrument must be switched

off for charging.

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• To summarise:

• Flue Gas Analysers are expensive measuring instruments that benefit from good

house keeping and regular routine maintenance.

• Excess Carbon Monoxide >4,000ppm sampled by the analyser can damage the

gas sensor.

• Never leave the analyser unattended whilst taking a flue sample.

• If the sensors are exposed to water, there is a high risk of damage.

• Maintain a dry water trap to prevent water damage. Also condensation sits in the

probe hose, remove by tipping probe downwards, dispose of safely as the

condensate is slightly acidic.

• The filter in the probe can get wet, particularly on condensing boilers. Simply

detach filter and replace with a dry one.

• Prevent storage of instrument in subzero temperatures as the electrolyte solution

in the sensors will freeze and measurements can not be taken. The sensors will

return to normal as the ambient temperature rises above zero.

• Inspect your flue probe and hosing regularly for damage and ensure that the flue

probe thermocouple in the probe tip is protected.

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Analyser messages

• High CO level purge in fresh air

• O2 sensor depleted

• CO sensor depleted

• Ambient temperature sensor not working?

Zeichen setzen für die Zukunft Zeichen setzen für die Zukunft Committing to the future Committing to the future

Looking after your Flue Gas Analyser

looking after your flue gas analyser

Education

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