The highest permissible concentration of carbon monoxide in the workplace is 30 ppm (parts per million). Escaping carbon monoxide can very quickly accumulate to a life-threatening extent in enclosed and semi-enclosed spaces. A Testo carbon monoxide meter enables reliable detection of this insidious gas.
CO meter from Testo – the perfect solution for every requirement

A Testo CO meter has the following qualities
- Can immediately be used at lightning speed without any zeroing phase.
- Detects carbon monoxide in the environment, even in the smallest of concentrations.
- Easy and safe to handle.
- Optical and acoustic alarm if limit values are exceeded.
CO measurement made easy: CO meters from Testo
CO meter with connectable probes H3>
CO meter with permanent probes H3>
Probes
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Flue gas analyzers
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Always keep an eye on CO content in air: for optimum ambient conditions
Ambient CO measurement H3>
What is CO?
Carbon monoxide is a combustion gas (harmful gas) that is released when combustion processes are incomplete. The most frequent day-to-day sources of CO are:
- petrol engines
- gas ovens
- heating systems
- solid fuels, such as wood and charcoal.
Carbon monoxide is colourless and odourless and prevents the blood from taking up oxygen when too great a concentration is breathed in. Breathing in a CO concentration of 700 ppm in an enclosed space leads to death after around 3 hours in an adult.
This is how to deal with flue gas analysis reliably and efficiently
A dangerous gas like carbon monoxide requires measuring instruments which are particularly reliable. To be on the safe side, you have to know which CO meter detects flue gas absolutely reliably. You should take the following into consideration:
- CO sensor: In order to be able to detect even small CO concentrations, a CO meter should have a CO sensor with a high level of measuring accuracy and a large measuring range. The testo 315-4 warning/measuring instrument is recommended – also ideal for the installation and maintenance of gas boilers.
- CO monitor: An easy-to-read display ensures that you can record measuring values quickly and respond to a raised CO concentration immediately.
- CO warning: Is an optical warning signal sufficient? Where CO meters are involved: certainly not. An additional acoustic warning should really be standard for CO measurement. This means safety is still guaranteed, even without being able to see the meter.
- Zeroing phase: CO meters without a zeroing phase are ready for use straight away. Important when you have to be quick. Little tip: keep CO meters on you with a belt clip. This means they are even more quickly to hand for fast checking.
Testo's CO meters mean you are ideally equipped – and can do your job even more reliably, professionally and quickly.
How to contact us.
Do you have any questions?
We would be more than happy to help you.
testo 317-3 with alarm function – The carbon monoxide meter for fast checking H2>

Measure CO using the testo 317-3:
- CO quickly determined: no zeroing phase means the instrument is ready for use straight away.
- Always perfectly prepared: thanks to permanent CO probe.
- Doubly reliable: gives an optical and acoustic warning when CO is present.
- CO measuring range in flue gas or indoor air: 0 to 1,999 ppm.
testo 317-3 in the webshop H2>
What ambient parameters would you like to measure?
Discover more Testo measuring instruments
As market leader, we offer you a diverse range for everything that can be measured:

CO₂ meters
Sound level meters
Light meters
Rpm measuring instruments
Which rpm measuring instrument is best suited to your tasks? You will find out here. Testo offers you a multi-layered range for contact measurement via a measuring wheel, reflective marker or light beam – ideal for industry, air conditioning technology and other fields of application.