Product category:
Process and OEM Valves
News Release from: Parker Hannifin Instrumentation Products Division | Subject: RH4 relief valve
Edited by the Engineeringtalk Editorial
Team on 18 February 2000
Relief valve precision-adjustable up to
413 bar
High-pressure relief valve is precision-adjustable up to 413 bar - 8 adjustable spring options, and low-friction action, ensure precise crack/re-seal - choice of seals provides options for -56 to +20
Parker Hannifin has launched a relief valve for high-pressure fluids instrumentation applications which can be precisely adjusted to meet specific application requirements across an exceptionally wide 3.4-413 bar/50-6000 PSIG range A graduated selection of relief springs, coupled with a special internal low-friction coating, gives accurate and repeatable control over cracking and re-sealing pressures
The valve also comes with a choice of five high-performance seals, providing a much extended range of operating temperatures than has previously been available, as well as compatibility with most media.
This new valve provides a simple means of adding safety, environmental and equipment protection to a wide variety of high-pressure process instrumentation.
It has uses in oil, gas, chemical, petrochemical, pulp and paper industries, and in applications such as control system panels, analytical systems, pumps and compressors.
The new valve -- the Parker RH4 -- is manufactured from forged 316 stainless steel with a 1/4-inch or 6mm flow port which can either direct media to a safe place, or release over-pressures to atmosphere.
Eight selections of relief spring allow accurate and sensitive adjustment of cracking pressure over the 3.4-413 bar/50-6000 PSIG range.
The operating range of each spring is colour coded for convenience and maintenance efficiency, and provided with an identically coloured label band for the cap, for at-a-glance identification of rating.
Fine adjustment is achieved via the cap, which may be secured in position by a locking nut and wire once the pressure is set, to guard against tampering.
Thanks to a captured moulded seat design, and other features, the new valve can withstand pressures of up to 551 bar/8000 PSIG during relief, providing a wide safety margin which allows it to be used in very demanding application environments.
To enhance the performance and accuracy of the valve's operation during cracking and resealing, Parker applies a very low-friction synergistic coating to the internal body bonnet.
This provides a smooth path for lower stem travel and, additionally, helps assure repeatable cracking.
Compared with competitive 'proportional lift' relief valves - which typically offer one or a few springs to cover their operational range - Parker's arrangement provides great resolution over crack pressure settings.
The new RH4 also complements an existing relief valve for low pressure applications, which offers seven choices of spring for pressures from 0-27.6 bar/400 PSIG -- providing accurate protection for a wide spectrum of instrumentation applications.
Numerous user-definable parameters give instrumentation designers and installers great freedom of application.
These include: choice of integral A-LOK double-ferrule or CPI single-ferrule end connectors for imperial and metric tube sizes, male or female NPT threaded inlet/outlet ports; five standard seal materials for compatibility with a wide range of media, and a wide spectrum of temperatures: Fluorocarbon rubber (-26 to +204C); Buna Nitrile rubber (-34 to +135C), Ethylene Propylene rubber (-56 to +135C), Neoprene rubber (-43 to +121C), and Highly Fluorinated Fluorocarbon rubber (-29 to +93C); and an optional valve handle which provides a manual over-ride facility that permits upstream pressure relief without changing the pre-determined cracking pressure. Request a free brochure from Parker Hannifin Instrumentation Products Division ...
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