Direct-acting, pressure reducing valve

Capacity: 5 gpm20 L/min. | Cavity: T-163A
PRBR : Direct-acting, pressure reducing valve
Technical Features [ + ]

Direct-acting, pressure reducing valves reduce a high primary pressure at the inlet (port 2) to a constant reduced pressure at port 1. These valves incorporate a damped construction for stable operation allowing the use of high reduced pressure.

  • Note: This valve has no relieving capability. It should not be used in a dead-headed application. If the reduced pressure side of the circuit has very low leakage the pressure may rise significantly. The pressure rise will vary from valve to valve.
  • This type of valve, PR*R, is a good replacement for an LP*C as a normally open, restrictive compensating element if a higher pressure drop across an orifice is needed.
  • Full reverse flow from reduced pressure (port 1) to inlet (port 2) may cause the main spool to close. If reverse free flow is required in the circuit, consider adding a separate check valve to the circuit.
  • All spring ranges are tested for correct operation with 5000 psi (350 bar) inlet pressure.
  • Suitable for accumulator circuits since the absence of pilot control flow results in reduced secondary circuit leakage.
  • Direct operated version offers superior dynamic response compared to equivalent pilot operated models.
  • Pressure at port 3 is directly additive to the valve setting at a 1:1 ratio and should not exceed 5000 psi (350 bar).
  • Leakage specified in Technical Data is out of port 3 with a supply pressure of 2000 psi (140 bar) and the valve set at mid range. This leakage is directly proportional to pressure differential and inversely proportional to viscosity expressed in centistokes.
  • Incorporates the Sun floating style construction to minimize the possibility of internal parts binding due to excessive installation torque and/or cavity/cartridge machining variations.
Technical Data [ + ]
Cavity T-163A
Series 0
Capacity 5 gpm20 L/min.
Factory Pressure Settings Established at 2 in³/min.30 cc/min.
Maximum Operating Pressure 5000 psi350 bar
Maximum Valve Leakage at 110 SUS (24 cSt) 2 in³/min.30 cc/min.
Adjustment - Number of Clockwise Turns to Increase Setting 55
Valve Hex Size 3/4 in.19,1 mm
Valve Installation Torque 20 - 25 lbf ft27 - 33 Nm
Adjustment Screw Internal Hex Size 5/32 in.4 mm
Locknut Hex Size 5/8 in.16 mm
Locknut Torque 80 - 90 lbf in.9 - 10 Nm
Model Weight .30 lb0,15 kg
Seal kit - Cartridge Buna: 990163007
Seal kit - Cartridge Viton: 990163006
Performance Curves [ + ]
FAQs [ + ]

Yes. If you look in the sandwich section you will see that we offer many such packages. When you are pressurizing B, A is connected to tank, allowing the reducer to do its job. When you reverse, the drain or tank port of the reducer is pressurized by A. This increases the setting of the reducer and helps keep the reducer open in the reverse flow direction.

Our reducing valves are outside-in valves; the supply pressure on the outside of the working parts is higher than the inside. At some pressure differential, the outside (sleeve) will close in on the piston and cause the valve to stick. A D range is adjustable from 25 to 800 psi with a maximum differential of 2000 psi. This means you could set the valve at 600 psi and expect it to work correctly with a supply pressure of 2600 psi. The valve may work at higher differentials, but we do not recommend it. The W and C ranges are tested over their entire range with an inlet pressure of 5000 psi. All direct-acting valves are tested with an inlet pressure of 5000 psi.

Direct-acting valves are used to prevent over pressure, and pilot-operated valves are used to regulate pressure. If you are unsure, use a direct-acting valve. Sun's direct acting valves are very fast, dirt tolerant, stable, and robust. Sun's pilot-operated valves are moderately fast, they have a low pressure rise vs. flow curve, and they are easy to adjust.

There are exactly 250 Sun drops in a cubic inch or 15 in a cc.

Pressure setting tolerances are listed in our Performance Data page. A link to this page can also be found in the Additional Resources tab of the applicable product page.

Yes. A reducing or reducing/relieving valve is normally open. If the pressure in the secondary circuit is less than the setting, it will be open.

2 caveats: (1) If the valve is in the reducing mode and you suddenly reverse the flow, the valve will not have time to open and will shift into relieving mode or (2) If the back flow generates a pressure drop through the valve that exceeds the setting, the valve will shift into the relieving mode.

When in doubt, use a reverse flow check.

Additional Resources [ + ]