Upon disassembly of the unit, a small amount of moisture was detected in the regulator's low pressure cavity, particularly on the backside of the flow control housing.It was found that the orifice plate was seized in the bonnet.The seized orifice plate prevented flow selection.The cause of the failure appears to be the moisture which can cause the nylon orifice plate to swell.In such a condition, subsequent rotation of the flow control knob can cause the orifice plate to become stripped from the flow control shaft so that the shaft rotates independently from the orifice plate.This can result in the loss of flow control or a no flow condition, depending upon the position of the orifice plate.In this instance, it was confirmed that the orifice plate was seized in the "off" position, which explains the observed no flow condition.Western was unable to identify the exact source of the moisture.This valve was replaced.
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