With the many different types of valves and improvements that have occurred recently, it is difficult to find a single trend. Users' requirements can range from extremely compact, easily adjustable or highly accurate and consistent to automatic operation depending on the application. This section presents valves for three different applications: metering, relief and priming. Although they may meet other trends, there is an easy aspect to all of them.
RELIEF VALVES
Available in low to high pressure models ranging from 5 to 6,000 psig, Hoke R6000 right angle relief valves provide accurate and consistent cracking and reseat pressures. In the 5 to 550 psig range, the low pressure valves have a raised seal lip to minimize contact with the seat. This eliminates friction and prevents O-ring overstress. A frictionless poppet provides the accuracy and consistency for cracking and reseat pressures. To protect the seat from damage due to contamination or particulates within the flow media, an encapsulated seat seal ensures minimal surface area contact. Six spring pressure ranges provide different cracking set pressures. However, to easily fit the application, customers can order preset narrow cracking pressure ranges or specific pressures. In the 150 to 6,000 psig range, the high pressure valves also incorporate a raised seal lip. In these models, a balanced, frictionless poppet design ensures constant cracking pressure regardless of back pressure. Typical applications for the valves include beverage dispensing equipment, gas pilot plants, petrochemical test labs, and pharmaceutical sterilization and packaging systems.
MINIATURE METERING VALVE
With a length of approximately 1.1 inches, Beswick Engineering's new miniature metering valve certainly can be called miniature. The unit's mechanical stops allow positive positioning of the sleeve in either the full ON or full OFF position. An engraved scale allows reliable positioning of the flow at any point between the two stops and a set screw mechanism locks the sleeve in place. To prevent flow setting changes, the seals and valve sleeve are vibration tolerant. Sleeve rotation permits positive shut-off and maximum flow adjustments. Rated to 200 psig maximum inlet pressure, the radial inlet's orifice size can be selected to match the approximate maximum flow required in the application. The new miniature metering valves target medical, dental and laboratory equipment, aerospace equipment, the fuel cell industry, industrial robots, and semiconductor manufacturing equipment among others.
AIRBLEED PRIMING VALVES
Wanner Engineering's Hydra-Cell C80 Series Airbleed Priming Valves open and close automatically. To allow F/G-20 through D/G-12 Series Hydra-Cell pumps to self-prime, the valves automatically open to relieve the system of trapped vapors or air and then automatically close to deliver full system pressure. This process avoids compressing the gas that can lead to pump airlock. Designed to operate in systems with a minimum discharge pressure of 75 psi (5 bar), the valves are tested to handle pressure up to 2,500 psi (172 bar). With operating temperatures up to 200F, the valves are offered a flow range of 1.5 to 10 gpm (5 to 37 l/min). Available in a variety of materials, the easy to install valves mount horizontally or vertically to meet various application requirements.
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