Parker Instrumentation's PED-certified, proportional relief valve can provide protection over a range of pressures from 150 to 6000 psig (10.3 to 414 bar).
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Parker Hannifin’s Instrumentation Div., Barnstaple, UK, has developed a PED-certified, proportional relief valve that can provide protection over a pressure range of 150 to 6000 psig (10.3 to 414 bar). It is certified to Europe’s Pressure Equipment Directive (PED), which covers a wide range of applications, including hydraulic fluid power equipment. In fact, it meets the PED’s highest level of Category IV.
Parker will set and test the new valve at the factory to specific application pressures and laser etch the valve body with the cracking pressure. The valve provides a simple fit-and-forget solution for adding reliable safety and environmental and equipment protection to a wide variety of applications because it needs no testing or calibration by the end user.
Designated HPRV, the new valve is available with 0.142-in. (3.6 mm) flow ports. At the heart of the valve is a captured seat design that is blowout and chip resistant and works across the valve’s entire operating pressure range. It accommodates pressures to 8000 psig (552 bar) during relief.
Color-coded springs configure the valve for eight cracking pressure ranges from 150-375 to 4975-6000 psig (10.3-24.1 to 345-414 bar). Fine adjustment can then be adjusted by the end user via an external nut, which is secured in position by Parker's Tru-Loc mechanism and a lock wire to eliminate the possibility of accidental movement and guard against tampering.
Compared to some other relief valves, the HPRV provides higher resolution of cracking pressure settings, which can be maintained to within 3% of the setting. Precision and repeatability is also aided by the valve's balanced poppet design, which ensures consistent cracking operation regardless of system backpressure to 2000 psig (138 bar).
The standard valve comes with integral A-Lok compression tube ends, eliminating threaded connections and the potential problems associated with thread sealants. Other end styles can also be specified to suit the installation, such as single-ferrule CPI end connectors for imperial and metric tube sizes, and male or female NPT threaded inlet/ outlet ports. The valve's outlet port can be configured to duct media to a safe place, or release over-pressures to atmosphere.
O-rings adapt the valve to different media at temperatures from –57 to 204° C (–70° to 400° F). Because HPRV valves are 100% PED certified, they require no additional paperwork or approvals.
"For this relief valve design we went back to the drawing board and created a universal solution that will function at pressures up to 6000 PSI, which accounts for the vast majority of instrumentation applications," says Mat Davis of Parker Instrumentation.