Yoshitake GD-20R and GD-20RC are primary pressure regulating valves and pressure sustaining valves designed for water, oil, air, and other non-dangerous fluids. These valves relieve excess pressure caused by load fluctuations and keep the internal pressure of piping constant during pump operation. They are also widely used to sustain water pressure inside piping when the pump of an open circuit system for mid-rise or high-rise building equipment is shut down.

Features

• No Leakage: Assures no leakage when closed due to a single seat valve and valve disc design.
• Reliable Response: A large diaphragm ensures a reliable response to pressure fluctuations and shutoff.
• Pump Relief: Used as relief valves for pumps, relieving excess pressure caused by load fluctuations and maintaining constant internal piping pressure during pump operation.
• Pressure Sustaining: Used to sustain water pressure inside piping when the pump of an open circuit system for mid-rise or high-rise building equipment is shut down.
• Corrosion Resistance: For the GD-20RC, the internal and external surfaces of the body are coated with Nylon 11, offering excellent corrosion resistance.

Specifications

Model	GD-20R	GD-20RC
Application	Cold and hot water, Oil (kerosene, heavy oils A and B), Air, Other non-dangerous fluids	Cold and hot water, Oil (kerosene, heavy oils A and B), Air, Other non-dangerous fluids
Pressure Regulating Range	15A–80A: (A) 0.05–0.25 MPa, (B) 0.26–0.7 MPa 100A–150A: (A) 0.05–0.25 MPa, (B) 0.26–0.5 MPa	15A–80A: (A) 0.05–0.25 MPa, (B) 0.26–0.7 MPa 100A–150A: (A) 0.05–0.25 MPa, (B) 0.26–0.5 MPa
Fluid Temperature	5–80°C	5–60°C
Fluid Viscosity	600 cSt or less	600 cSt or less
Body Material	Ductile cast iron	Ductile cast iron
Valve Seat	Stainless steel or Bronze	Stainless steel or Bronze
Valve Disc & Diaphragm	NBR	NBR
Connection	JIS 10K FF flanged	JIS 10K FF flanged
Inside Surface Treatment	15A–100A: Electrodeposition coating 125A–150A: Tar-based coating (Black) or Electrodeposition coating	Nylon 11 (inside and outside surfaces)

INFO

• Available with FKM.
• Available with external sensing type.
• Available with stainless steel trim parts.
• Available with stainless steel construction (15A to 100A). Please contact us about the availability of 65A to 100A for all stainless steel.
• Available with a drain plug.
• Depending on the additives contained in the oil, the deterioration of rubbers may be accelerated.

Dimensions and Weights

Nominal Size	L (mm)	H (mm)	H1 (mm)	Weight (kg)
15A	145	309	57	8.2
20A	150	309	57	8.2
25A	150	330	67	10.0
32A	195	395	76	17.3
40A	195	395	76	17.3
50A	195	409	81	19.2
65A	270	555	105	40.0
80A	270	582	120	43.7
100A	308	645	135	70.0
125A	380	849	169	144.0
150A	400	918	204	173.0

Weights are for GD-20R.

The material shapes are slightly different depending on the nominal size.

Piping Example

Install a needle valve to the outlet side of the product and plumb it to the pressure sensing pipe using copper piping.

Flow Characteristic Chart

Set Range (MPa)	Accumulation (MPa)
0.05–0.25	Within 0.05
0.26–0.7	Within 0.105

Nominal Size Selection Chart (For Liquid)

Example of Selection

When selecting the nominal size of a differential pressure regulating valve whose differential pressure (ΔP), specific gravity, and flow rate (V) are 0.2 MPa, 1 (water), and 5.5 m³/h, respectively, first trace down vertically from the differential pressure (ΔP) of 0.2 MPa to find intersection point (a) with the flow rate (V) of 5.5 m³/h. Since this intersection point (a) lies between nominal sizes 25A and 32A, select the larger one, 32A.

When the specific gravity is 0.7 under the same conditions, trace down vertically from the differential pressure (ΔP) of 0.2 MPa to find intersection point (b) with the specific gravity 1. Find intersection point (c) with the specific gravity of 0.7 by tracing horizontally to the slant lines from this intersection point (b). Then, find intersection point (d) with the flow rate (V) of 5.5 m³/h by tracing down vertically from intersection point (c). Since this intersection point (d) lies between nominal sizes 20A and 25A, select the larger one, 25A.

Structure and Operation

If the adjusting screw is turned right, the diaphragm will be depressed with the adjusting spring and the valve connected with the spindle will close.

Fluid passes along a conductor pipe and the sensing chamber under the diaphragm. If the pressure of the sensing chamber becomes higher than the setting pressure, the load of the diaphragm bottom will overcome the load of the adjusting spring, will push up the valve, and will relieve excessive pressure.

If the pressure of the sensing chamber falls below the setting pressure, the valve will be again closed by the load of the adjusting spring.