Yoshitake GD-24 water pressure reducing valve can be used as a pressure control unit in water supply systems of general residential housing, high-rise buildings, industrial plant, and factory equipment. It can also be used to provide stable water pressure in high-rise apartment units, and for hilly districts where each house requires an individual water supply system. Trouble-free flow control solutions are achieved through the use of a stainless steel valve seat and a suspension type clamp in the drive mechanism.

Features

• Wetted parts are made of corrosion-resistant material to prevent rusty water.
• Highly wear-resistant and durable stainless steel valve seat.
• Closed structure keeps fluid inside even if the diaphragm is damaged or broken.
• Horizontal or vertical piping is possible.
• If a large capacity is required, valves can be installed in parallel.

Options

• GD-24G: D-type 1.0MPa pressure gauge
• GD-24S: Strainer (SY-24, 60 mesh as a standard)
• GD-24GS: Gauge and strainer

Pressure gauge connection port is JIS Rc 1/8.

Specifications

Model	GD-24
Application	Cold and hot water, Flushing water
Inlet pressure	0.2-1.6 MPa
Reduced pressure	0.05-0.55 MPa
Minimum differential pressure	0.05 MPa
Maximum pressure reduction ratio	10:1
Application temperature	5-80°C*
Connection	JIS Rc screwed

** Do not use the valve continuously at a temperature of 70°C or above (catalog notes).*

Material

Part	Material
Body	Cast bronze / Bronze
Valve disc	Urethane rubber
Valve seat	Stainless steel
Diaphragm	EPDM / NBR
Cap	Bronze / Brass
Plug	Stainless steel

Dimensions and Weights

Nominal size	d	L	H	H1	Weight (kg)
15A	Rc 1/2	80	193	41.5	1.8
20A	Rc 3/4	90	210	45	2.4
25A	Rc 1	100	230	50	3.3
32A (31A)	Rc 1-1/4	120	265	60	4.7
40A	Rc 1-1/2	150	315	62	8.2
50A	Rc 2	185	365	73	14.3

(Dimensions in mm)

Construction

No.	Name of parts	No.	Name of parts
1	Body	12	Washer
2	Spring Chamber	13	Nut
3	Cap	14	Adjusting Spring
4	Valve (Disc)	15	O-ring
5	Valve Seat	16	Bolt
6	Suspension Metal	17	Sealed Nut
7	Diaphragm Shell	18	Spring
8	Diaphragm	19	Plug
9	Spring Plate	20	Label
10	Adjusting Screw	21	Spring Washer
11	Lock Nut

Operation

Turning the adjusting screw (10) to compress the adjusting spring (14) and the load of adjusting spring is introduced to the diaphragm (8) and suspension metal (6) to open the valve (4). Then, the fluids begin to flow from the inlet side through the upper side of the valve. The reduced pressure is led to the diaphragm to be balanced with the adjusting spring load, and control the valve travel to maintain the reduced pressure.

Nominal Size Selection

ΔP: Inlet/reduced pressure differential (MPa)

Cv Value:

Nominal size	15A	20A	25A	32A	40A	50A
Cv value	1.5	1.9	3.0	4.0	7.0	10.0

Characteristics Charts

Flow Rate Characteristics Chart

Pressure Characteristics ChartThis chart shows variation in reduced pressure when the inlet pressure of 0.6 MPa is changed between 0.2 MPa and 1.6 MPa while the reduced pressure is set at 0.2 MPa.

Installation

Piping Example

Installation Warnings & Cautions

• Relief Valve: In case installing a safety relief valve as a safety device at the outlet side, joint relief pipe at the outlet of the safety relief valve and guide it to a safe place.
• Strainer: Install a strainer (Screen: 60 mesh) at the valve inlet side.
• Flushing: Remove foreign matter and scales from the lines before installing the valve.
• Gauges: Install a pressure gauge at both the inlet and outlet sides of the valve.
• Distance: When installing quick open and close valves (such as a solenoid valve), secure at least 3 m from the valve. When pressure reducing in two stages, secure at least 3 m between the valves.
• Direction: Install the valve in proper direction of the fluid flow.

Maintenance Space Secure the necessary maintenance space at the installation site of the pressure reducing valve.

Nominal size	A	B
15A	245	105
20A	270	115
25A	290	130
32A	340	145
40A	420	150
50A	480	165

Operating and Adjustment Procedure

Operating Cautions

• Do not touch the pressure reducing valve directly with bare hands after flowing hot fluids to prevent burns.
• When opening the by-pass stop valve, ensure that the reduced pressure will not exceed the set pressure of the safety relief valve.
• When operation is discontinued for a long period of time, completely purge fluid from the pressure reducing valve and piping system.

GD-24 pressure reducing valve is set at 0.1MPa at the factory. Change the set pressure as appropriate:

1. Close the stop valves at both sides of the pressure reducing valve, and thoroughly purge the system through the by-pass line. When completed, be sure to close the by-pass valve.
2. Slowly open the inlet stop valve, then open the outlet stop valve slightly, allowing a trickle to be discharged.
3. Loosen the lock nut, and slowly turn the adjusting screw (clockwise to increase, counterclockwise to reduce) while observing the outlet side pressure gauge.
4. Slowly open the outlet stop valve to its full-open position.
5. After the adjustment, tighten the lock nut.

Maintenance and Troubleshooting

Maintenance Precautions

Completely discharge internal pressure from the valves, lines, and equipment, and cool the valve down to a level where you can touch it with bare hands before disassembly and inspection.

Consumable parts and replacement period:

• Diaphragm (8): 3 years
• O-ring (15): 3 years

Troubleshooting:

Problem	Cause	Countermeasure
Reduced pressure exceeds prescribed level	1. Diaphragm is damaged. 2. Foreign matter is embedded in the valve and/or valve seat, or scratches exist.	1. Replace the diaphragm. 2. Disassemble and remove foreign matter. If scratches exist, replace it.
Pressure does not rise to the desired level	1. Strainer is clogged. 2. Pressure gauge malfunction.	1. Disassemble and clean. 2. Replace the pressure gauge.
Leakage	1. Loosen Bolt (16). 2. Loosen Cap (3). 3. Broken O-ring (15) for cap.	1. Tighten Bolt (16). 2. Tighten Cap (3). 3. Replace O-ring (15) for cap.
Abnormal noise is heard	The suspension metal (6) is in incorrect position.	Correct the position of the suspension metal (6).

Exploded Drawing