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Cedar Grove, NJ, USA: Plast-O-Matic Valves has developed a high-flow capacity 3" NPT Relief Valve, for corrosive and ultra-pure liquids. Because of the many functions this valve performs, it is also known as a back pressure regulator and bypass valve.
The Series RVTX is an angle-pattern valve constructed of Grade 1, Type 1 PVC with a choice of Viton or EPDM elastomeric seals. The sensing element is a solid PVC shaft (or stem) with a Teflon thrust washer to reduce friction; working in conjunction with a large area rolling diaphragm. This feature enables the valve to open more rapidly, providing greater flow and sensitivity to changing pressure. Control is provided by a stainless steel spring, which is not in contact with liquid. The valve adjusting bolt and lock nut are high density polyethylene (HDPE). External fasteners are stainless steel.
Relief/back pressure setting is infinitely adjustable from 5 to 100 psi. When pressure drops below the set point, the valve automatically reseats with a bubble-tight seal. Maximum flow rate is 200 gallons per minute. Designed for heavy duty industrial use, the RVTX is ideal for acids, salt solutions, and other highly corrosive liquids. The design can be customized or made in other materials for special needs.
New York, NY, USA: Plast-O-Matic Valves, Inc. introduced a new air-controlled pressure regulator, Series PRA, at the 1999 Chem Show, November 16. Designed for highly corrosive and ultra-pure chemicals, this new regulator uses compressed air to control pressure with greater accuracy.
Pressure regulators provide protection for valuable downstream instruments and filtration systems by converting fluctuating or excessive inlet pressure to a preset maximum downstream pressure. The PRA will routinely handle inlet pressure up to 150 psi and accurately maintain a downstream pressure from 5 to 125 psi.
The design of the PRA features two opposing large area frictionless rolling diaphragms. Process pressure is applied to one of the diaphragms; air pressure is applied to the other. Because the air pressure can be maintained with more accuracy than the force provided by a spring, the PRA offers greater sensitivity and less variance from set pressure than any thermoplastic pressure regulator previously available. The PRA was demonstrated at the 1999 Chem Show in combination with Plast-O-Matic's new Stabilizer (patent pending) which measures downstream liquid pressure to provide even greater sensitivity and performance.
In addition to its enhanced performance Series PRA is the first regulator available with Plast-O-Matic's patented Fail-Dry® safety feature. The Fail-Dry is a vented chamber between two seals that provides advance warning of a primary seal failure while the valve is still 100% operable.
Series PRA is available in a number of rugged thermoplastics, including
Grade 1 Type 1 PVC, Natural Polypropylene, and Kynar® PVDF. Elastomers
are Viton®, EPDM, or Buna-N. Pipe sizes range from 1/4" through 3".
Cedar Grove, NJ, USA: Plast-O-Matic Valves, Inc. has announced the availability of a new air-piloted, thermoplastic 3-way valve with position indication/verification. The valve is designed to toggle between two isolated ports opposite a common port. Unlike many 3-way valves, usage of two different corrosive or ultrapure liquids through the same valve is feasible, as the two inlet/outlet ports are not shared.
The valve has two inlets and one outlet. One inlet is normally closed and the other is normally open. Because this valve uses a "balanced design," meaning all seal diameters are equal, it can also be used in reverse with one inlet and two outlets. The "balanced design" also permits a wide range of pressure ratings (full vacuum to 100 psi) at any port whether inlet or outlet.
A spool-type shaft opens and closes the ports. The valve is designed with the upper port normally open to the common port, and 40-100 psi air pressure is applied to the pilot to force the shaft down and open the lower port. When air is exhausted, an isolated, non-wetted spring returns the shaft to its original position, closing the bottom port and reopening the top port. The design ensures that one port closes off before the other opens keeping liquids from the separate ports from co-mingling.
The valve provides electronic position indication that verifies which port is open at a given time. When the shaft is in its "normally up" position, a magnet on the shaft energizes a hermetically-sealed sensor indicating that the top port is open. The signal is used to light an LED display or electronically transmit the valve position to a control system. When air pressure forces the shaft down thus closing the lower port, contact is broken on one sensor and a second sensor is energized.
This lightweight, compact valve is equipped with stainless steel fasteners. The ports are standard NPT piping with a 1/8" air port and 1/4" inlets/outlets. Choices of body materials include PVC, CPVC, polypropylene, and PVDF with Viton or EPDM seals. Custom sizes to 3" NPT are also available.
The Series RV Back Pressure Regulators are available in a choice of proven designs for specific uses in a piping system. Designs include angle patterns with a molded Teflon® shaft for smooth operation, and in-line models which feature a rolling diaphragm that eliminates crystallization problems.
Back Pressure Regulators are usually installed directly in the piping line at the end of a closed loop to create backpressure in the system. Typically, this ensures that pressures to branch lines or tools off the main line will always be in the range of the pre-set pressure. They are also used as relief valves to protect equipment and systems against dangerous overpressures or sudden pressure surges.
In pumping applications, Back Pressure Regulators are used as bypass relief valves to prevent pumps from "dead heading" due to unexpected shut-offs downstream. They are also ideal for creating backpressure to a pump, to increase pump efficiency and smooth out turbulence.
Back Pressure Regulators are available in pipe sizes from 1/4" -
3" with various body materials including Grade 1, Type 1 PVC, Polypropylene,
Corzan® (CPVC), Kynar® (PVDF) and Teflon® (PTFE). Seal materials
are Buna-N, Viton, EPDM or Teflon. Flow rates range from 2 to 200 GPM and
set pressures from 5 to 150 PSI. The valves can be factory modified for
special applications.