2. Sample Tube

This should be stainless steel for gases drier than -40ºC dewpoint, copper or carbon steel type can be used for wetter gases. If the sample pipe needs to be flexible then only PTFE pipe should be used. For good system response 3mm OD (1/8") should be used, however 6mm (1/4") pipe can be used where pressure drops across 3mm tube are too high.

Note: If the main process gas is very cold or very hot, it will be necessary to extend the length of the pipe sufficiently to allow the sample to reach a temperature which is within the operating range of the sensor (ie. -10ºC to +50ºC).