Parker’s H series proportional pressure relief valves are designed to provide an automatic protection mechanism for process instrumentation systems. When the upstream pressure exceeds the closing force exerted by the valve’s spring, the lower stem opens and permits flow through the valve’s outlet port - which can be ducted to a safe
place or vented to atmosphere. The flow rate increases proportionately to the increase in upstream pressure.

The valves offer a choice of 14 different ranges of opening (or ‘cracking’) pressures, from 10-25 to 4,975-6,000 PSI (0.7-1.7 to 343-414 bar). A low friction stem seal and a balanced poppet design ensures accurate and consistent cracking pressure, regardless of system back pressure. Cracking pressure is maintained to within 3% of its setting, and can be finely adjusted by means of an external nut, secured in position by Parker’s unique Tru-Loc™ mechanism.

The connections are available in 6 mm and 1/4" sizes, and with choice of male or female NPT, Parker CPI™ single ferrule or Parker A-LOK® double ferrule compression fittings.

All H series pressure relief valves are manufactured from 316 stainless steel. The maximum operating pressure rating and permissible temperature range depends on the particular model. For maximum applications flexibility, there is an extensive choice of O-ring seal materials, including fluorocarbon rubber, Buna-N, ethylene propylene rubber, highly fluorinated fluorocarbon rubber and neoprene rubber.

Parker’s H series proportional pressure relief valves are CE marked and certified to the highest Category-IV level of the Pressure Equipment Directive (PED).


Markets:

• Chemical
• Oil and Gas
• Petrochemical

Features/Benefits:
• Captured molded seat design is blow-out and chip resistant
• Color coded springs and labels indicate spring cracking range
• Unique Tru-loc™ facility prevents accidental adjustment
• Lock wire feature secures a given pressure setting
• Low friction stem seal design prevents friction which increases accuracy of cracking pressure and reseat pressure
• Balanced poppet design ensures consistent cracking pressure regardless of system back pressure
• High Pressure Orifice sizes: 3.6 mm(0.142”) Low pressure Orifice sizes: 5.2mm (0.203”)
• Multiple end connections available
• Low pressure relief valve pressure settings are externally adjustable. Six different spring ranges provide greater system sensitivity and enhanced performance

Applications:
• Process Instrumentation systems
• Skid Panels
• Storage Tanks/Vessels