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Proportional Relief Valve offers protection from 150-6,000 psig.

Press Release Summary:

Available with 0.142 in. flow ports, HPRV, PED-certified valve features captured seat design that is blow-out and chip-resistant, as well as balanced poppet design for operation in back pressures up to 2,000 psig. Range of color-coded springs configure valve for 8 cracking pressure ranges, and fine adjustment is achieved by external nut secured by Tru-Loc mechanism and lock wire. O-ring seals adapt valve for use with different types of media over temperatures from -70 to +400°F.

Original Press Release:

PED-Certified Proportional Relief Valve Offers 'Universal' Protection Solution for Process Instrumentation

o category-IV PED device can be set to crack from 150 - 6000 PSIG (10.3 - 414 bar)
o available in threadless configurations for very high integrity and reliability

Barnstaple, UK, February 21, 2008 --- Parker Instrumentation has developed a PED-certified, proportional relief valve for process instrumentation applications, with the ability to provide protection over an extremely broad 150 to 6000 PSIG (10.3 to 414 bar) pressure range.

CE marked and certified to the highest Category-IV level of the Pressure Equipment Directive (PED) which covers a wide range of applications including hydraulic fluid power equipment, Parker will set and test the new valve at the factory for specific application pressures, and laser etch the valve body with the cracking pressure. The new valve provides a simple 'fit and forget' solution for adding reliable safety, environmental and/or equipment protection to a wide variety of process and laboratory instrumentation applications, that needs no testing or calibration by the end user.

Designated HPRV, the new valve is available with 0.142 inch/3.6 mm flow ports. At the heart of the innovation is a novel captured seat design that is blow-out and chip-resistant and works across the entire operating pressure range (the valve will handle pressures up to 8000 PSIG/552 bar during relief). A range of colour-coded springs configure the valve for eight cracking pressure ranges of 150-375, 325-775, 725-1525, 1475-2275, 2225-3025, 2975-4025, 3975-5025 and 4975-6000 PSIG (10.3-24.1 to 345-414 bar). Fine adjustment can then be achieved by the end user by means of an external nut, which is secured in position by Parker's unique Tru-Loc mechanism and a lock wire to eliminate the possibility of accidental movement and guard against tampering.

Compared with some competitive relief valves, this arrangement provides great resolution over crack pressure settings. A low friction stem seal design further aids control of cracking pressure, which is 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 back pressures up to 2000 PSIG (138 bar).

As standard, the valve is provided with integral A-Lok compression tube ends, eliminating threaded connections and the potential problems associated with thread sealants such as PTFE tape. Other end styles can also be specified to suit the installation, and include 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-ring seals adapt the valve for use with different types of media over temperatures from -57 to 204 degrees C (-70 to +400 degrees F). Five choices of material are available: fluorocarbon rubber and nitrile rubber for general-purpose use, ethylene propylene or neoprene rubber for compatibility with a wider range of chemicals, or highly fluorinated fluorocarbon rubber which is compatible with a very wide range of chemicals.

Each HPRV valve is provided as a complete item including spring, under a single order number, to simplify purchasing. The valve is 100% PED certified, and requires no additional paperwork or approvals to use the product. Parker has additionally set up its manufacturing and assembly process to ensure short lead-times and can supply the valve anywhere in Europe in five working days.

"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. "We believe it will simplify life for both users and purchasers."

About Parker.

Parker Instrumentation is part of the Parker Hannifin group. With annual sales exceeding $10 billion, Parker Hannifin is the world's leading diversified manufacturer of motion and control technologies and systems, providing precision-engineered solutions for a wide variety of commercial, mobile, industrial and aerospace markets. The company employs more than 57,000 people in 43 countries around the world. Parker has increased its annual dividends paid to shareholders for 51 consecutive years, among the top five longest-running dividend-increase records in the S&P 500 index. For more information, visit the company's web site at, or its investor information site at

Parker Instrumentation Products Division, Europe, Riverside Road, Barnstaple EX31 1NP, UK, Tel: +44 (0)1271 313131;

Parker Instrumentation Products Division, 1005 A Cleaner Way, Huntsville, Alabama 35805-6708, USA. Tel: 256 881-2040;

Parker Hannifin Middle East, PO Box 46451, Abu Dhabi, United Arab Emirates. Tel: +971 2 6788587;

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