Pressure Sustaining or Back Pressure Regulating Valves regulate upstream pressures by relieving the surplus pressure downstream or via a return line (when installed in a tee). They work in much the same way as a relief valve (normally closed, opening at the set pressure) but are more accurate, responsive and only open far enough to relieve sufficient pressure to maintain the desired pressure upstream. The pressure to be maintained is known as the set pressure and is easily adjusted by turning the adjusting bolt, thus compressing the spring (clockwise increases the set pressure, anti-clockwise reduces the set pressure).
There are some general rules to help select the best regulator and the best control for each application:-
• Unlike other valves where the valve size matches the pipe size, these pressure control valves must be “sized”, using the differential between upstream/downstream pressures and considering whether the valve has to bypass a small percentage of the flow or the whole output of the pump. For this reason it is not unusual to select a valve that is different to the pipe size.
• Self acting valves are the simplest design and represent the lowest cost but they are not as accurate as pilot operated valves.
• Always use the lightest spring (smallest range that covers the set pressure)
• Where high pressures occur upstream and there is minimal back pressure downstream, the high differential pressure may cause cavitation. Some of the effects of cavitation can be excessive noise, premature wear of valve or other components in the downstream piping. A simple remedy is to create some back pressure (e.g. install a globe valve, partially closed) in the downstream piping.
The following range is extensive, mainly because every regulator has limitations on sizes, materials of construction, suitability to various media, inlet pressures and reduced pressure ranges. In addition to the metal bodied valves offered below, good quality Thermoplastic sustaining valves (DHV716/725) can be found on this website.Read More...
Jordan JB is an instrument style back pressure regulator, made from barstock and has the ability to handle high pressures (max inlet 3,000 psi, max set pressure 750psi), large differential pressures and very low flows (Cv’s 0.15-0.35). Standard body material is 316L with exotics like Hastelloy or Monel as options. Seat options are PTFE or PEEK and there are a number of set pressure ranges between 5-50 psi→200-750 psi.
Sizes: ¼” (DN8); 3/8” (DN10) 1/2" (DN15)
Treloar/Jordan 4350 is the Australian made version of the US manufactured Mk50 and is available in sizes from ½”→2” (Cv’s 0.84-50). It is a robust, versatile, self acting, pressure sustaining valve that has sliding gate, long life Jorcote seats, rather than conventional piston or plug and seat ring. It is suitable to use with water, oil, gas, chemicals and steam. There are many variations to the basic model such as 4351(high sensitivity, low droop), 43501 (high flow version) and 4350HP (high pressure version). In Bronze or DI version, valves have screwed ends BSPT, 316ss (fabricated/machined body) valves can be threaded, socket weld, butt-weld or flanged to Ansi 150/300 or AS Tables D/E. In all body materials, where a valve is smaller than the pipe size, valves can be flanged up to match the actual pipe size. Cv’s from 1.6 to Cv200
Maximum inlet pressure- BZ (2100 kpa) / DI (3,100 kpa) / 316SS (4,500 kpa)
Maximum temp- BZ/DI (260°C)/ 316SS (343°C)
Sustaining pressure ranges: 4350 (many ranges between 14 kpa-1,276 kpa)
4351 (many ranges between 3.5 kpa-1,190 kpa)
4350HP (ranges between 525 kpa-3,150 kpa)
Options: Low flow trim, special coated seats, Jorlon long life diaphragm, cryogenic extension, Oxygen cleaned, salt water trim, Companion flanges to Bronze & DI valves, flanges welded to body for 316ss.
Jordan MK57 series is a pilot operated pressure sustaining valve and provides greater accuracy and lower offset than can be achieved with self acting valves. It is available in sizes ½”-6” (Cv’s 5.0-395) and consists of a main valve with a small, pilot valve. The Mk57 combines the short stroke of the sliding gate with the action of a pilot valve to create a faster, more accurate response (less droop as flows increase). Can be used where greater accuracy is required than self acting valves or where control systems are not an option.
Suitable for steam, water, oil, gas and chemicals. Available with NPT threaded ends (1/2”→2”) or Ansi 150/300 flanges (1/2”→6”)
Several adjustable pressure ranges from 70-210 kpa→552-1280 kpa)
Options: BSP ends, on threaded valvesRead More...