Welker CP-2 Constant Pressure Cylinder

Designed with an internal piston and seals, the CP2 cylinder is pressured with an inert gas supply, and then turned around and filled slowly from the opposite end. By letting the gas push against the piston,slowly venting the pre-charge gas, the sample is taken at full line pressure from start to finish. Then, in the laboratory, a gas supply could be connected to the pre-charge side equal to the pipeline pressure. As the sample gas is injected into the chromatograph, the piston is being pushed by the pre-charge gas. While the cylinder is being emptied, full pressure is being maintained and the gas composition is not being altered as a result of pressure reduction. The cylinder can be stored or sent to another laboratory for confirmation, and when the remaining gas is analyzed, it will give repeatable results, because the condition of the gas is maintained by the constant pressure cylinder. The cylinder is equipped with valves, safety reliefs, and gauges on both ends and thus the pressure can be controlled and monitored at all times on both ends.

This procedure has proven to give extreme accuracy in both spot sampling procedures as well as in automatic sampling systems. The Constant Pressure Cylinder has been tested against laboratory and on-line chromatographs, and has shown to maintain the integrity of the sample to within BTU of the pipeline gas. No other cylinder design comes close.