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Relief Valves at Stra-Val
21 Columbus Avenue
Garfield, NJ 07026
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(973) 340-9955 (973) 340-9933
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New orders must placed from within the product pages, by clicking on the appropriate product tab

This website has pricing. To view pricing, typical ship schedules, or place  an order, just click on a product tab and make your selection which you can customize. You may print or e-mail yourself a quote 24/7 without factory assistance, or send in a quote request for un-priced items.

Model PRS-09i 

In-Line Pressure Regulator (Reducing Valve)

See Pricing Table Below

Pressure Regulator in-Line
  • Spring operated diaphragm pressure reducing valve
  • 1/2"-2" NPT THD
  • Normal Inlet pressures to 150 PSI (10 Bar), Body rated 220 psi (15 bar) (Higher Inlet pressures are possible with higher outlet pressures using a relief valve set no higher than 100 psig) See applications
  • Outlet pressures from 8 PSI to 80 PSI (5.5 Bar) (multiple spring ranges)


  • Water pressure regulator and air pressure regulator parts made from solid bar stock materials — unlike castings which have wall thickness variations.
  • Body: Standard valve materials are stainless steel (all sizes) and some brass (1/2"-1" sizes only). Monel, titanium, Alloy 20, and Hastelloy model also available.
  • Trim: Stainless steel on valve poppet and seat is standard. 
  • Metal or Soft Seats: Choose metal seats for Class ANSI IV shuttof or Soft seat Class VI (bubble tight) shutoff with appropriate elastomers. See Elastomer choices below
  • Teflon-Viton composite reinforced diaphragm is designed for much greater poppet travel than the stainless steel diaphragm valve models PRS-05. Teflon film on the wetted side provides superior protection when used as a corrosion-resistant valve for a wide range of fluids and gases, chemicals, petroleum products, and steam. Viton is used on the non-wetted side of the diaphragm. Max temperature rating is 350 °F for most applications. Buna backing is available for lower temperature applications
  • In-line valve ports: Simplifies installation for new or existing piping. This water pressure regulator and air pressure regulator valve can also be used as a steam pressure regulator and is also available with ANSI flanges (see PRS-09i-FLG). Our pressure-reduction valve is also available as a sanitary valve with sanitary flanges in all-stainless steel construction.
  • Spring chamber: Standard material is carbon steel as it is non-wetted, but can be upgraded to a stainless steel valve when the external environment is corrosive or sanitary.


This is a direct-acting diaphragm pressure-reducing valve (most often referred to as a pressure regulator) with an adjustable spring operating against a flexible elastomeric diaphragm subjected to the reduced outlet pressure of the valve which is controlled through an internal sensing port. This makes the valve an accurate pressure-sensing valve, or pressure-control valve used to control outlet pressures with a wide range of inlet pressures.

Unlike unbalanced diaphragm pressure-reducing valves, this pressure valve is a balanced inlet design and will work quite well on applications where the inlet pressure will fluctuate widely and will have little effect on outlet pressure. The valve will operate in a vertical orientation as illustrated, horizontal, or any other orientation.

This valve can be used for non-corrosive or mildly corrosive fluids including steam, depending on the materials selected. See material display notes in pricing section to help select materials. Use only clean, strained or filtered fluids to keep the pressure-regulating valve operating at maximum efficiency without clogging. Use our Stra-Val in-line strainer fitting model STF-05 or basket strainers SBS-10 or SBV-05 to keep the fluids clean. Use a #20-#40 mesh range as a minimum to keep solids from entering the valve.

Applications are for use as a water pressure-reducing valve, water pressure regulator, steam pressure regulator, air pressure regulator, oil pressure regulator. Most applications are sold where a corrosion-resistant valve is preferred, where we manufacture these mostly as a stainless steel valve for the wetted components, using type 303 stainless steel or type 316 stainless steel for chemicals or when a sanitary valve is required with sanitary flanges. For seawater applications the Monel valve, titanium valve, or Hastelloy valve is used. Although Inlet pressures of up to 220 psi (15 bar) are possible, we  do not recommend it unless the largest spring range is selected and there is a relief valve that is set not to exceed 100 psig (6.9 barg) on the outlet side of the valve. This relief valve  will assure that the downstream pressure will never reach full inlet pressure in case the regulator fails to shut off properly for any reason. In fact we always recommend a relief valve be installed on the outlet side of the valve which should be set slightly higher than the highest pressure that the regulator will be adjusted to to protect equipment downstream from the regulator in case of excessive pressure buildup which may be from seat wear, corrosion, or external sources other than the valve.

The standard construction for this pressure-reducing valve is with a metal seat, but a soft seat option can be ordered, which will improve seat leakage particularly for air or gases.Therefore, do not attempt to use this as a shutoff valve even when the valve is furnished with a soft seat option. For prolonged or even momentary periods of shutoff, install separate shutoff or isolation valves to keep the relief valve from tripping.

This in-line pressure regulator has fairly adequate Cv values for most applications. See below. For higher flow rates and larger Cv values, a custom pressure valve model PRS-09 with the porting arrangement parallel and slightly offset which requires additional elbows to restore in-line piping.

We now offer some models that meet NACE MR0175. These are not priced on line. Consult factory.


Select the valve size, spring range, material options in the customized pricing and ordering section indicated by the red arrows. You have the ability to customize your valve choices by selecting the wetted and nonwetted materials, and choice of seat materials to suit your shutoff requirements, using the softer seats for improved shutoff, particularly for air or gas applications. Once these selections are made a price quote can be generated and printed directly to your computer or immediately e-mailed to you.

Principle of Operation

The valve operates on the principle of balancing the spring force that is set by the user against the outlet pressure acting under the diaphragm. There is an internal pressure balancing port that subjects the outlet pressure directly to the underside of the diaphragm. When the outlet pressure falls below the set pressure required by the system on the outlet side of the valve, the spring force overcomes the force balance under the diaphragm causing the poppet and diaphragm assembly to drop down causing the valve to open and allow higher pressure at the valve inlet to pass through the valve. When the pressure rises to a sufficient level to restore the force balance against the spring, the valve will move toward the closed position. The valve is completely self regulating and the poppet is constantly moving to respond to pressure changes on the outlet side of the valve, not the inlet. The only time the poppet closes completely is when the outlet pressure has been reached to its set point. As long as the valve is able to shut off properly without solids or other material build up in the seat or because of seat wear, the valve should be able to maintain and hold the outlet pressure and keep it from rising for brief periods of time. If the valve is set with no flow passing through the system, there will be some droop (drop in outlet pressure) caused by relaxation of the spring when the valve first has to open. This occurs with all direct spring operated valves and can be compensated by making a slight readjustment to the set pressure once the desired capacity has been achieved.

Metal Seated Regulator PRS09i
See Below
Pressure regulator in-Line Npt connections
Metal Seated PRS09i-EX PRS-09i-EX
Stainless Steels
Material List and Specification

Materials-Metal Seated
1. Adjusting screw Steel or SS
2. Lock nut Steel or SS
3. Spring chamber Steel or SS
4. Spring pusher Steel or SS
5. Adjusting spring Cr-Sil Steel(coated) or SS
6. Main valve Stainless steel (303 or 316) or custom Alloys
7. Lock nut Steel or SS
8. Nut, diaphragm Steel or SS
9. Diaphragm PTFE / Viton or PTFE/Buna
10. Seal Viton (std)
11. Body Stainless steel (303 or 316) or custom Alloys
12. Bottom plug Stainless steel (303 or 316) or custom Alloys
13. Seal Viton
14. Lock washer Steel

Dimensions (inch) Flow Data
NPT A B C D Cv Flow orifice inch GPM*
1/4 2.25 1.53 7.25 0.67 .219 3.4
3/8 2.50  1.78  7.38 1.38  .313 6.9
1/2 2.50  1.88  7.50 1.98  .375 9.9
3/4 3.00 1.88 7.75 3.53 .50 17.6
1 4.00 2.13 12.00 7.95 .75 40
1-1/4 4.00 2.38 12.50 10.3 .81 51
1-1/2 5.50 2.63 13.50 14.9 1.00 75
2 5.75 3.25 13.75 23.3 1.25 117

*Flow is in USGPM based on 25 PSI pressure drop

Note: Dimensions are approximate and are subject to change without notice. Request certified dimensions before final product installation.

Soft Seated Regulator PRS09i
See Below
Soft Seated Regulator PRS09i
Stainless Steels
Material List and Specification

Materials- Soft Seated
1. Adjusting screw SS or upgrade
2. Lock nut SS or upgrade
3. Spring chamber SS or upgrade
4. Spring pusher SS or upgrade
5. Adjusting spring  SS or upgrade
6. Main valve Stainless steel (303 or 316) or custom Alloys
7. Lock nut SS or upgrade
8. Spring Carrier
SS or upgrade
9. Diaphragm PTFE / Viton or PTFE/Buna
10. Seal, Piston
Viton, Epdm, Buna, Ptfe
11. Seat, Elastomeric
Viton, Epdm, Buna, Ptfe
12. Seat Holder
Stainless steel (303 or 316) or custom Alloys
13. Screw Stainless steel (303 or 316) or custom Alloys
14 Body Stainless steel (303 or 316) or custom Alloys
15 Bottom Plug Stainless steel (303 or 316) or custom Alloys
16 Seal Viton, Epdm, Buna, Ptfe
17 Lock Washer  300 series St. Steel

+ Click here for Pricing/Ordering Instructions
Customized Pricing & Ordering Information ($USD)

To show prices:

Click on a size:
1/4" PRS09i-02T 3/8" PRS09i-03T 1/2" PRS09i-05T 3/4" PRS09i-07T
1" PRS09i-10T 1 1/4" PRS09i-12T 1 1/2" PRS09i-15T 2" PRS09i-20T
To price or order, first select a size above.


Please enter the number of units and choose the Factory Set pressure (value must fall within the selected spring range) or select "None (valve set by customer)."

To enter multiple values with different set pressures, simply add rows to this form and specify a quantity and value for each row. The total number of units specified here will determine the overall quantity for your shopping/quotation cart. These steps are used for pricing only and do not require a purchase.

When an order is placed these set pressures will be laser engraved onto the valve nameplate. If "None" is selected the valves will be factory set to the low end of the spring range or near zero. Final adjustment will be required by the user after installation.

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     (Valve will be set in the field)

      (Range:   -  )

      (Range:   -  )

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Please enter the number of units.


To display pricing, print or e-mail a quotation or order, you must follow these basic steps:

1.) Select one of the product groups, spring range for Valves (Perf or mesh for Strainer products)

2.) Click on a spring Range and Cv (Valves) or Perf or mesh (Strainers). Options will now appear with price adders.

3.) If your pressure units are different from the ones listed, click on the units header "?" to convert.

4.) By placing your mouse over each option you will see a pop up display with helpful information including temperature limits for that material or option

5.) As you click on each option, you will see the subtotal change. You must click on all available options before proceeding to the next step.

6.) Click on the large "Continue" button to apply quantity and resale discounts, Print, E-mail the quote to yourself, or to Order.  You  will be given a  resale discount code if you are an eligible reseller or OEM.

+ Click here for product-specific instructions