Pressure gauge protection valve - prevents pressure build up due to leaks by venting gauge to atmosphere

摘要

The valve body (3) has a central (5) connected by the hole (8) to the pressure gauge (2) and connected by the hole (6) to the pressure line (7). A plunger (10) with sealing rings (28, 29) fits in the bore (5). The lower end of the plunger (10) projects into a chamber (13) connected to the pipe (7) by the hole (12). The plunger (10) is held in its lower position by the spring (16) so that the pressure gauge (2) communicates with the pressure line (7) via the annulus (11) around the middle portion of the plunger (10). When the pressure exceeds the safe level, the plunger is pushed upwards shutting off the hole (6) and connecting the hole (8) to the atmosphere via the hole (9).