| 摘要 |
<p>A pressure relief valve comprises a housing (10) having a stepped bore comprising a first portion (18) and a second portion (18) extending through the housing (10). An annular shoulder is formed in the housing to define a valve seat (19). A piston (22) is slidable in the housing (10) and a spring (30) biases the piston (22) into engagement with the seat (19). The spring (30) is retained by a cap (32). A seal between the piston (22) and the seat (19) is made by an 0-ring (25) located in an annular groove (23). Passageways (37) adjacent the seat (19) communicate the exterior and interior of the housing (10). The total cross-sectional area of the passageways (37) is less than the area of the second bore portion (20) causing, in operation, a pressure build-up in the first portion (18) below the piston (22) which increases piston movement.</p><p>The pressure relief valve is particularly suitable for use on life rafts.</p> |
