About Selecting the Proper Dräger (or other brand) Gas Detection Tube
Gas Detection Tube and Gas Pump Must be Compatible: Interchanbgeability of gas detection tubes & pumps
Colorimeteric gas detection tubes produced by different manufacturers are not necessarily interchangeable among gas detection pumps. Be sure that the gas detection tube you are using is one recommended for use with your gas detection pump - check both the gas detection pump manufacturer's instructions and the gas detection tube manufacturer's specifications.
For example, as we were informed in May 2008 by Nextteq GastecTM detection tube distributor in the U.S., Gastec tubes that are currently available are not intended for use on the SensidyneTM gas detection pump.
At one point in time, Sensidyne had the contract for Gastec tubes and lost it due to rebranding. The tubes they sell now are Kitagawa tubes, not Gastec. We don't want to confuse anyone out there that they can use a Gastec tube with the Sensidyne pump. The Gastec tubes are not calibrated to work with a Sensidyne pump and therefore, the reading could be incorrect and prove fatal in some cases.
Really? MiIchael Shaw (Interscan Corporation, a producer of gas detection & recording systems) disagrees with the accuracy of the above quote. Here is an excerpt [edited for clarity] from what Michael wrote to us in March 2015:
The sample size is 100 ml. Gastec and Kitagawa colorimetric gas detection tube systems are essentially identical.
Dräger system uses the same test volume, but the sampling tube contents are not as densely packed.
A bellows pump cannot pull sufficient vacuum through the Japanese-produced gas detector tubes. But then, bellows pump is [in my opinion not a great] idea, in that with Dräger design, multiple squeezes (not at all reproducible) are needed, and it is very prone to leaks. It is however a less costly sampling pump design.
Comment: I have been using precision calibrated classic hand-operated plunger type gas pumps, field-calibrated electrical pumps equipped with a flow meter, and also the Dräger bellows pump for more than a decade. My Dräger pump has not seen heavy use but in my application it still works like new. I have tested different types of gas detector pump and tube systems against one another and found the results virtually identical.
Photograph of a Drager hand pump used to measure carbon dioxide levels in the environment.The accuracy of Draeger samplers and detector tubes has also been studied for several decades and the accuracy of the bellows-pump design is well-established.
OPINION: I found that the precision of the piston pump could be deceptive. Failure to maintain the required coating of Si grease in the pump chamber, for example, produced a palpable difference in pump stroke force required and variations in the pump seal changed the time between the point at which I locked the pump pull-handle up and the time that the pump stopped drawing air. These variations left me uncertain about the true pump volume being moved. The bellows pump looks less precise but in my experience, tested by repeating measurements at the same location and time, produced very consistent, repeatable results.
Our company has kinds of detection tube system. Except Drage, we also have Kitagawa, Gastec and China you can choose.