CO2 Monitors

[gb555]

Does anybody have advice on how often a CO2 monitor needs to be calibrated and what steps are taken during this process. The use of the monitor is to vary the ventilation depending on the occupancy of a gymnasium.

 

[MPcontrol1]

I think it depends on the type of CO2 sensor you buy. The only one I trust and are familiar to are from Veris Industries. They have a 5 year warranty and they self calibrate themselves. Here is a link you can check out there eng specs and manual.

http://www.veris.com/product.asp?idMainCategory=41&idCategory=59&idProduct=45

 

[ChasBean1]

CO2 control presents calibration issues with NDIR sensors... They're affected by barometric pressure and they tend to drift. Typically you could buy small (75L) disposable calibration gas bottles. Look up "Calibration Gases." Get a zero air and a 1,000 ppm standard, plus an adapter from the CO2 sensor manufacturer. Run the zero air through and set the "zero" setscrew until you get a zero reading. Run the 1,000 through and adjust the "span" setscrew until you get a 1,000 ppm reading. If the span had to change a lot, repeat the zero and span... I would do this quarterly.

Some sensors might need a different cal process - first look at the manual for the sensor...

CB

 

[STYMIEDPIPER]

Many corporations who own their CO2 monitors should have a documented safety procedure on file whereas the monitors should be checked at some designated frequency. If at a plant, ask the safety personnel. Other companies that do not want to take the responsibility of maintaining the monitors will rent the equipment. The rental company is then responsible for servicing the monitors. The rentals can be as needed, monthly, or yearly.
If you know the manufacturer of the equipment you can contact them for their recommendations. Otherwise, contact some local suppliers in your area and see what type of responses you receive.
I know that this is not quite the answer you wanted but it should point you in the right direction to make a proper decesion.

 

[pesy]

Why do copper-fin water heaters require minimum flows? What would happen if it was provided 40F inlet water, and set to 200F outlet water?

a) Is it an issue of scale build-up?
b) Is it an issue of melting fins?

What is the reason for (a) or (b)--Does it occur only because there is unequal flow distribution among the various tubes, or is the distribution relatively equal and it occurs anyway?

Are there fin-tube products that don't have these limitations?

I ask because I'd like to design a new fin-tube heat exchanger that doesn't require minimum flows and I'd like to know what to look out for...

Thanks.