Valve is usually selected for corrosive or mildly corrosive fluids, depending on the materials selected (consult factory). When liquids or gases contain debris or other solid matter which might cause internal clogging or improper operation of the valve, a strainer with a fine wire mesh should be installed before the inlet of the valve. In-line strainer fittings STF-05-EX or basket strainer models SBS-10-EX can be purchased from Straval to solve this problem.
Do not use this valve where the inlet pressure will fluctuate widely as the outlet pressure may have to be readjusted. However, where this condition does exist and the outlet pressure needs to be controlled closely below 80 psi, a pressure-reducing valve with a balanced design is recommended such as the Straval model PRS09i-EX. Although the body has a high pressure rating, inlet pressures above 300 psi (~20 bar) are not recommended, especially when outlet pressures below 15 psi (~1 bar) need to be controlled. Even though the body can withstand pressures up to 1500 psi (~100 bar), permanent deformation to the diaphragm may occur if the seat is unable to shut off properly and will require replacement under these extreme conditions. For higher inlet pressures see our high pressure models PRH04-EX and PRH09-EX.
The pressure regulator can be selected with a metal to metal seat and one should not expect to use this as a shut off valve. Use separate isolation valves for that purpose. Seat leakage criteria will be to ANSI class IV leakage standards, so a relief valve is always recommended on the outlet of the valve to at least handle any pressure buildup that may occur just from seat leakage that could occur from seat wear, corrosion, or just dirt contamination trapped in the seat. A relief valve would also compensate for pressure spikes in the piping system or some mechanical failure in the pressure regulator caused by external circumstances. Use one of the soft seat options listed in the pricing section for each valve size to help achieve a tighter shutoff especially on air or gas service. However, when selecting elastomers, temperature limitations must be observed for these materials which are listed in the priced option section for each valve size.
Select the appropriate spring range and materials from the pricing/options table below. Both wetted and nonwetted parts can be selected. Choose a metal seat or soft elastomeric seats as shown below.
This is a direct-acting pressure-reducing valve with an adjustable spring operating against a flexible metal diaphragm subjected to the reduced outlet pressure of the valve. With the spring completely uncompressed and adjusting screw backed out, the inlet pressure will close the main valve and keep it shut as long as there is no external contamination in the valve and the valve seat is holding properly and deteriorated form corrosion or wear. This will shut off flow and reduce the outlet pressure to zero if the valve seat is sealing effectively. The only external possible leakage path is through the metal to metal seal created by the heavy duty metal diaphragm, body and spring chamber which makes this design suitable for severe and elevated temperature services. Because the diaphragm is metal, there is limited travel of the poppet and therefore the valve is suitable to very low flows only. If the valve is used on liquids that can solidify and the internal clearances and internal balancing port gets plugged up, the valve can no longer regulate properly. So use only clean, non solidifying liquids operating at liquified temperatures adding heat tracing to keep the product in a liquid, flowing form.