There are a range of issues to consider in selecting pressure regulation equipment for analysis. The first is whether the gas supply is to go direct to the instrument or whether it it is to be via a more permanent piped connection. In the case of the latter, then it is more appropriate that rather than a simple regulation, a wall mounted gas panel is used with either hoses or pigtails to connect high pressure gas side from the cylinder or bank of cylinders to the pressure regulating device. For many monitoring applications however a more mobile solution is the only practical way forward.

Once the type of installation is defined then a there are a number of questions which the user needs to answer to facilitate the selection of a suitable regulator. The main points are as follows:

Gas (nature, quality) : this defines the type of regulator: stainless steel or brass (stainless steel for corrosive gases, no chrome for the CO, no brass with more than 66% copper content for Acetylene, fittings compatibility, etc)

Regulator:
• Cylinder specification and pressure (the inlet fitting and inlet pressure are different
• Single or two stage according to the requested stability of outlet pressure

Operating conditions:
• Inlet and outlet pressure
• Flow

Special cases:
• To work in absolute pressure or below atmospheric pressure
• Preset pressure regulator

NB : For certain pure gases (CO₂, N₂O), and in case of larger flowrates: a heater can be required.

For calibration mixtures it should also be considered whether it is better to have a regulator with a small dead space to minimize passivation times. Likewise for expensive gases then having a regulator delivered with helium leak test certification also provides reassurance that you are making the best use of your gaseous resources.