Theory
91518 Multigas Analyzer Service Manual
3-6
Occlusion Valve
The occlusion valve is activated when the sampling becomes occluded. The main flow is then diverted to the
side flow of the D-fend water trap, to remove the occlusion.
Sampling Pump and Damping Chamber
The gas sampling pump is a membrane pump that is run by a brushless DC motor. The sample flow is
measured with a differential pressure transducer across a known restriction. The motor is automatically
controlled to maintain a constant flow, even when the D-fend water starts to become occluded. The pump also
enables use of sampling lines of varying lengths and diameters. The damping chamber is used to even out the
pulsating flow and to silence the exhaust flow.
Note:
The flow is never reversed toward the patient.
Figure 3-3: Gas sampling system
To Ref gas port
