The Yoshitake GD-41G and GD-43G are direct type pressure reducing valves designed for air, carbon dioxide gas, nitrogen gas, and steam for washing or sterilization. They feature a space-saving design and use stainless steel (SCS14A and SUS316) for wetted parts to enhance corrosion resistance.

Features

• Space saving and resource saving are achieved.
• Stainless steel (SCS14A and SUS316) is used for wetted parts, improving corrosion resistance.
• PTFE covers the diaphragm contact surface to fluid, making the diaphragm highly durable and less liable to deteriorate.
• Special fluorine-contained rubber parts are resistant to corrosion.
• A pressure balance structure maintains the reduced pressure at a constant level without being affected by inlet pressure fluctuations.
• Applicable to piping washing, system washing, sterilization washing, and steam for sterilization.
• Horizontal or vertical installation is available.

Specifications

Model	GD-41G	GD-43G-10	GD-43G-20
Application	Air, Carbon dioxide gas, Nitrogen gas / Steam for washing or sterilization
Inlet pressure	0.07-2.0 MPa (0.2 MPa or less for steam for washing or sterilization)
Reduced pressure	(A) Yellow spring: 0.02-0.1 MPa (B) Red spring: 0.1-0.25 MPa (C) Black spring: 0.25-0.5 MPa
Minimum differential pressure	0.05 MPa
Maximum pressure reduction ratio	20:1
Fluid temperature	5-90°C (The maximum temperature of steam for washing or sterilization is 130°C. Allow an interval of at least four hours between steam flows.)
Body Material	Cast Stainless steel (SCS14A)
Valve disc Material	Special synthetic rubber (special FKM)
Diaphragm Material	Heat-resistant synthetic rubber and PTFE (PTFE applied to wetted face)
Connection	JIS Rc screwed	JIS 10K FF flanged	JIS 20K RF flanged

Notes

• The inlet pressure of GD-43G-10 is 0.07 to 1.0 MPa.
• If using for washing steam or sterilization steam, be sure that maximum temperature is 130°C and avoid continuous use for more than 30 minutes.
• Available with pressure gauge (JIS Rc 1/8 screwed).

Dimensions and Weights

GD-41G Dimensions

Nominal size	d	Weight (kg)
15A	Rc 1/2	1.2
20A	Rc 3/4	1.1
25A	Rc 1	1.0

All dimensions are same except connection size.

GD-43G Dimensions

Nominal Size	D	C	g	t	f	n-h	Weight (kg)
15A	95	70	51	14 (12)	1	4-15	2.8 (2.6)
20A	100	75	56	16 (14)	1	4-15	3.0 (2.9)
25A	125	90	67	16 (14)	1	4-19	4.0 (3.7)

The values in parentheses are the weights of the GD-43G-10. All dimensions are same except flange size.

Performance Charts

Specifications Selection Chart

Flow Characteristic Chart

Set pressure	Offset pressure
0.2 MPa or less	Within 0.05 MPa
More than 0.2 MPa	Within 0.08 MPa

Pressure Characteristic Chart

This chart shows variation in reduced pressure when the inlet pressure of 0.25 MPa is changed to 2.0 MPa while the reduced pressure is set at 0.20 MPa.

Nominal Sizes Selection Chart (For Air)

Operation and Installation

Fluid of Outlet

If the adjusting screw is turned right, the diaphragm will be depressed with an adjusting spring and Disc connected with spindle will open. The fluid which flowed in from the inlet side carries out the action which pushes up the diaphragm through a sensing hole at the same time it flows into outlet side through the Disc upper part. When the stop valve at the outlet side is closed, the load which pushes up the diaphragm increases, the load of an adjusting spring is overcome, and the Disc is closed.

Fluid of Inlet

If the stop valve at the outlet side is opened gradually, the load which pushes up the diaphragm will decrease, the load of an adjusting spring will be overcome, the Disc will be opened, and fluid will flow into the outlet side. The fluid which flowed into the outlet side through a sensing hole carries out the action which pushes up the diaphragm, maintains the balance with an adjusting spring load, adjusts the Disc opening, and keeps outlet side pressure constant.

Piping Example

Precautions during installation

• When installing a safety valve at the outlet side of the pressure reducing valve, connect a blow-off pipe to the outlet of the safety valve to lead the possible discharged fluid to a safety location.
• Before connecting the pressure reducing valve to the piping, remove foreign materials from the piping.
• Be sure to install a strainer at the inlet side of the pressure reducing valve (60 mesh or more recommended).
• When installing a quick opening/closing device (e.g., solenoid valve), the distance between it and the pressure reducing valve must be at least 3 m.
• When two stage pressure reduction is employed, the distance between the two pressure reducing valves must be 3 m or more.

Maintenance Procedure

Troubleshooting

Symptom	Possible Cause	Corrective Action
I. Reduced pressure is higher than set pressure	1. Damaged diaphragm	1. Replace the diaphragm unit
	2. Foreign material pinched between valving Disc and valve seat. Dents or scratches are seen on the valving element P or valve seat.	2. Clean the assembly. If the Disc is damaged, replace it. If the valve seat section is damaged, replace the valve casing.
	3. Poor seal of valve stem O ring	3. Replace valve stem O ring with a new one.
II. Reduced pressure is lower than the desired pressure. Fluid fails to flow.	4. Valve stem O ring is locked.	4. Replace valve stem O ring with a new one.
	5. Valving element P and valve seat is locked.	5. Clean Disc and valve seat section. If damaged, replace the respective parts.
III. Leakage	6. Loosen cross recessed pan head screw	6. Tighten cross recessed pan head screw.
	7. Loosen cap	7. Tighten lower cap.
	8. Broken O ring for cap.	8. Replace O ring for cap with a new one.

Exploded Drawing

Periodic Replacement of Expendable Parts

Component	Part number	Replacement interval
Diaphragm set	5, 6, 7, 8, 9, 18	3 years
Disc	4	3 years
O Ring	19, 20	3 years