Welker Probe (Automatic Insertion Instrument Regulator IRA-4SS)
Welker probe is a tool to sample gas from a pipeline and to present to the Gas Chromatograph system at specified pressure. It has safety features like a pressure release valve which vents excess pressure in case of wrong pressure setting, thus, saving the expensive Chromatograph equipment.
The details of the welker probe can be found here. The manual to install and retract the probe can be found here
Welker is fitted on top of the Gas line carrying high pressure gas through a flanged socket with Ball valve . The socket is welded on the pipeline. The ball valve must never be closed during the operation of the sample probe as significant portion of the probe is inserted into the gas line. closing the valve will damage the probe. The Probe has to be retracted from the line before closing the ball valve.
A write-up with pictures can be found here explaining the working of the probe .
Troubleshooting:
- Sample pressure drops below the preset value to 20 psi to about 3 psi
One reason is choke in the mesh of seat retainer (15) due to solid particles like chemicals and sludge accumulating. Remove the probe as per the removal instructions, and clean the mesh
- Sample pressure reduces even if the mesh is clean
This happened once because spring (14) lost its tension, it was not apparent but comparing the height to a new spare spring showed about one turn elongation. The spring was changed and sample pressure returned to 20 psi.