Environmentally Friendly Waste System

At the moment we have found the drager tube for the testing of CO2 and H2S. However, we have not been able to find a suitable drager tube for CH4. The drager tube for CO2 and H2S cost about SGD $156 and SGD$103 per pack of ten respectively. When we called the supplier to enquire about the drager tubes for CH4, he said that he does not sell drager tubes, but he does supply another brand called Gastec. It costs slightly more than SGD $80 per pack of ten. In addition, this particular methane detection tube would require the use of a pump which is over a hundred dollars.


The measuring range for CO2 drager tube is: 5-60 vol%

The measuring range for H2S drager tube is 1-60ppm


The working principle: a measured volume of gas (or air) is drawn through a tube which contains chemicals which change in color in response to the presence of a specific target gas (or range of gases) present in the sample.



To select the appropriate gas detection tube you need to know what gas or gases is/are to be detected, and at what probable concentrations the gas may be present, or at what level of exposure the test is to be conducted.


Each dragger tube also has a specific number of strokes required. Hence, it is important to take note of this before doing any measurements. After conducting measurements, the drager tubes should be flushed.



The "outlet" end of the detector tube is inserted into the gas collecting pump. The "inlet" end of the tube is exposed to the air to be tested, and the pump is operated for the required number of strokes before looking for a color change on the tube's gas concentration scale.