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Pressure-reducing valves-product-category

Pressure-reducing valves

Pressure-reducing valves limit pressure in one portion of a circuit without affecting system pressure. With flow ratings up to 300 l/min [80 US gal/min] and pressure ratings up to 350 bar [5,075 psi], they are available in direct-acting or pilot-operated types for pressure reducing/relieving or reducing alone.

Features and benefits 

  • Provide pressure control in systems requiring two or more different pressure settings   
  • Wide range of valves available  
  • All operating parts made of hardened and ground materials for maximum durability and leak protection 
  • Enhanced corrosion protection 
  • Can be supplied with zinc plating and anodized aluminum manifolds for additional corrosion resistance 
  • Direct-acting valves provide fast response and are economical solution for low flow applications such as hydraulic brake or motor shift 
  • Pilot-operated valves provide smooth, stable response for high pressure applications, along with precise pressure control with varying flow rates  

Applications  

  • Agriculture 
  • Construction 
  • Cranes and material handling
  • Forestry 
  • Lawn and turf 
  • Road building  

Basic operation 

Pressure-reducing valves are normally-open, pressure-limiting devices. They limit one part of a circuit to a pre-determined setting, while allowing the inlet pressure to rise to full system pressure, if necessary. They come in two forms: direct-acting or pilot-operated. Both types have the option of an integrated pressure relief valve, which limits the regulated pressure in the case of external forces. 

Direct-acting spool type with relief  

The direct-acting pressure reducing valve is normally open from port 2 to 1, with port 3 connected to tank. As the pressure at the regulated port 1 increases to the valve setting, the spool moves back against the spring and restricts the flow between port 2 and 1 to maintain the regulated pressure setting. This limits the pressure in port 1, while pressure in port 2 will continue to rise. If an external force creates excessive pressure in the regulated port 1, the spool will move further back and open port 1 to port 3, working as a relief valve. 

Pressure Reducing Direct Acting Spool With Relief Basic Op Drawing

 Pilot-operated spool type with relief  

The pilot-operated pressure-reducing valve is normally open from port 2 to 1, with port 3 connected to tank. As the pressure on the regulated port 1 increases to the valve setting, the pilot section will open and allow the main spool to shift and restrict flow from port 2 to 1. If the pressure in port 1 continues to rise, the main spool will move further back, blocking the line between port 2 and 1. This limits the pressure in port 1, while pressure in port 2 will continue to rise. If an external force causes the pressure in port 1 to rise above the valve setting, the main spool will shift further and open port 1 to tank port 3, acting as a relief. 

Pressure Reducing Pilot Operated Spool With Relief Basic Op Drawing

 

Direct-acting spool type without relief  

The direct-acting pressure-reducing valve without relief is normally open from port 2 to 1, with port 3 connected as a drain port only to tank. As the pressure at the regulated port 1 increases to the valve setting, the spool moves back against the spring and restricts the flow between port 2 and 1 to maintain the regulated pressure setting. This limits the pressure in port 1, while pressure in port 2 will continue to rise.  

Pressure Reducing Direct Acting Spool Without Relief Basic Op Drawing

 Pilot-operated spool type without relief  

The pilot operated pressure reducing valve without relief is normally open from port 2 to 1, with port 3 connected to tank. As the pressure on the regulated port 1 increases to the valve setting, the pilot section will open and allow the main spool to shift and restrict flow from port 2 to 1. If the pressure in port 1 continues to rise, the main spool will move further back, blocking the line between port 2 and 1. This limits the pressure in port 1, while pressure in port 2 will continue to rise. 

Pressure Reducing Pilot Operated Spool Without Relief Basic Op Drawing 

Typical application diagrams 

Pressure Reducing Valves App Diag 

Pressure-reducing valve comparison 

Characteristic/type

Direct-acting reducing

Direct acting reducing/relieving

Pilot-operated reducing

Pilot-operated reducing/relieving

Dirt tolerant  - - - -
Fast acting + + - -
Flow - - + +
Pressure - - + +
Stable - - + +
Relative Price [1 lowest] 1 1 2 2