HOMETechnical DataPressure reducing's outline
If water pressure is inappropriate in a water supply and distribution piping system, use of water becomes inconvenient and water facilities cannot be efficiently used.
- If water pressure is too high: Increased water supply, increased leakage, and abrasion of the connected sections of the water distribution piping system and reduced life span of the system
- If water pressure is too low: Short flow supply, resulting from lack of supply pressure
1) Direct operating type
It regulates the water pressure on the outlet side by operating the valve based on the spring’s elasticity and outlet-side water pressure.
- How it works -
① Outlet-side water pressure < Spring force
② Valve opens
③ Water on the inlet side flows to the outlet side
④ Outlet-side water pressure > Spring force (If only a small amount of water is used or is not used at all on the inlet side)
⑤ Valve closes
⑥ The balance between the outlet side and spring force maintains a certain set pressure level
2) Pilot type
A main valve and an auxiliary valve exist as a set, and the auxiliary valve is referred to as the pilot. The auxiliary valve is a small, direct operating pressure reducing valve. The valve opens and closes based on the water pressure on the outlet side and the spring force. Water that passes through activates the main valve.
- How it works -
  • Outlet-side water pressure < Spring force
  • he auxiliary valve opens
  • Water from the main valve passes through points D, E, and F, and flows in the direction of point G
  • Water at A, the upper part of the main valve diaphragm, flows in the direction of point D(If only a small amount of water is used or is not used at all on the inlet side)
  • Volume of water that was filled up at A goes down
  • The diaphragm moves upwards
  • The valve closes
  • Water on the inlet side flows to the outlet side
  • Hydro pressure on the outlet side rises
  • Hydro pressure on the outlet side of the pilot pushes the diaphragm in the direction of the spring, resulting in the pilot closing
  • Flow from point F to point G is cut off
  • Water on the inlet side of the main valve passes through points C and D and moves to point A
  • The diaphragm is pushed in the disc direction, and the valve closes
  • The set pressure on the outlet side is maintained through the repetition of the process above

① The secondary pressure, which was reduced through the main valve, actuates the pilot diaphragm through the pressure sensing tube.

② This reduced secondary pressure adjusts the secondary pressure by responding to the force of the pressure regulating spring that is installed on the
upper part of the pilot diaphragm

① When the secondary pressure drops, the force of the pressure regulating spring becomes bigger than the force of the lower part of the pilot diaphragm, resulting in the diaphragm pushing downwards to open the pilot valve.

② When the pilot valve opens, the steam of the primary goes through the pressure regulating tube and reaches the lower part of the main diaphragm located at the lower end of the pressure reducing valve’s body.

③ The main diaphragm overcomes the pressure of the return spring and opens the main valve. Steam is supplied to the secondary and thus the secondary pressure is adjusted.

① When the secondary pressure rises, it actuates the pilot diaphragm, thus adjusting the opening percentage of
the pilot valve. The return spring pushes the main valve, and the steam of the lower part of the main diaphragm moves along the pipe and is discharged through the orifice.

② The steam pressure and pressure of the lower part of the main diaphragm adjusts the opening degree of the main
valve according to load fluctuations, based on a balance maintained by the opening percentage of the pilot valve.
This is how a constant secondary pressure level is maintained immediately after pressure changes or load fluctuations.
If an electronic valve or other valve for rapid opening and closing is installed on the secondary of a pressure reducing valve, have it located as far away from the pressure reducing valve as possible. Failure to do so may cause, in some cases, noises and vibrations.
To enable disassembling and inspection, secure enough space above the center of the pipeline that is at least 3 times the H2 length of the pressure reducing valve dimensions; and belo.
Set or support the pipeline at the inlet and outlet of a pressure reducing valve so that the gravity or thermal stress of the pipeline is not directly inflicted upon the pressure reducing valve.
In new pipelines, most pressure reducing valve breakdowns are caused by foreign substances. Before having steam pass through the pressure reducing valve, completely remove foreign substances within the pipeline by blowing them out through the bypass.
There are cases where two pressure reducing valves are used in parallel because of the lack of flow with one valve.
In case of parallel use, pressure reducing valves are self-operated valves, and thus there is a difference in pressure sensitivity.
This is why the set pressure needs to be different. It is also recommended that each valve be used independently as much as possible.
Hunching or vibration can occur if condensate gets into a pressure reducing valve.
This is why there is a need to adopt a piping method that blocks condensate entry or to remove condensate.