ABSTRACT
A PRV can malfunction in a variety of ways. To troubleshoot a PRV, install pressure gauges to read inlet pressure at test port TP1 and outlet pressure at test port TP2 (Figure 11.1), and use these readings to examine:
Decaying set pressure (low pressure at port TP2). If pressure at the outlet port drops below the desired set pressure, check the pilot head cone and seat for excessive wear which may permit increased drain flow (Figure 11.2). Excessive drain flow through this section of the valve reduces the pressure needed in the chamber above the main spool to increase valve pressure drop and bring operating pressure in the branch circuit up to the desired value.
