Home Forum Hardware Measure CO2 in a 100°c Sauna ?

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    Walker Angell

    How can I accurately or somewhat accurately measure CO2 (and other stuff) in a sauna? Most electronics are rated for either 65°c or 50°c while a sauna is often about 100°c at 1m above the upper bench – at the level where most people are breathing.

    I currently place devices such as A3, IQAir, M501 and others at a level where the temps will not exceed the max for the device. This is OK but I question how accurate the measurements are. If there is good mixing of air then the measurements might be good but otherwise not so good.

    I have also done some tests with only heating the sauna up to 50 or 65°c. I can do this alone and guesstimate what measurements would be with 2, 4 or 6 people. I’d have difficulty getting others to do it with me though. I also wonder if there are differences at the higher heat levels that I’d not be capturing. Finally, I’d like to take measurements continuously while the sauna is in use and while different ventilation strategies are being tested.

    One thought is to use something like an A3 with a long tube attached so that the A3 electronics could stay at a lower temp and air from higher where people are breathing then be sucked in to the sensors. I assume I’d need a long enough tube in a low enough area of the sauna for the air being sucked in to cool down sufficiently? Maybe an external blower in the tube to help out the one in the A3? Will the tube itself cause poor readings? What adjustments will need to be made to what measurements to insure some level of accuracy?

    Other thoughts?



    I opened a discussion with one of the NDIR sensor manufacturers, explaining these requirements to them. In short, they said the high temperature is problematic.

    Your idea with the buffer tube is good, and we did something similar in the past, when several A3s were installed on buses and wanted to have some protection from the high pressure jets used to wash them.

    But on PM2.5/PM10 readings there were two issues: 1) a decrease in amplitude, compared to units running at the outside. 2) a delay in registering the elevated readings, as the air had to slowly travel the tube.

    2) is not a problem for you. With enough time, 1) should reach the real value too. So if you can have this run for let’s say, half an hour, you should get close to the real value found in the hot area. You’ll need a tube + a fan, to force the air from the sauna all the way through.

    Planning on doing this anywhere soon? Let me know if we can help.

    Walker Angell

    As soon as we get the inaccurate CO2 problem fixed I’m planning to try this. Likely start w/ a 20′ (6m) tube w/ the inlet @ a spot of 65°c to see how much it cools and then adjust from there.

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