Yoshitake GD-45P and GD-45 are compact and lightweight pressure reducing valves designed for steam applications. They feature a simple structure for easy maintenance and are applicable to inlet pressures up to 2.0 MPa. The GD-45P model includes a handle made of Polyphenylene sulfide (PPS resin) for tool-free pressure adjustment, while both models incorporate an external pressure type bellows for excellent workability and a built-in 60 mesh strainer to protect the valve and seat from dirt.

Features

• Compact and lightweight design.
• Simple structure and easy maintenance.
• Applicable to inlet pressure of up to 2.0 MPa.
• Built-in screen (60 mesh) to protect the valve and valve seat from dirt.
• Excellent workability accomplished by the external pressure type bellows of the pressure sensing part.
• Pressure adjustment is handle-operated without any tool (GD-45P).

Specifications

Model	GD-45 / GD-45P
Application	Steam
Inlet pressure	2.0 MPa or less
Reduced pressure	(A) 0.02-0.1 MPa (yellow spring) (B) 0.05-0.4 MPa (blue spring) (C) 0.35-1.0 MPa (yellow green spring)
Minimum differential pressure	0.05 MPa
Maximum pressure reduction ratio	10:1
Maximum temperature	220°C
Valve seat leakage	0.1% or less of rated flow rate
Body Material	Ductile cast iron
Valve, valve seat Material	Stainless steel
Bellows Material	Phosphor bronze
Connection	JIS Rc screwed

Handle Material

The material of the handle for GD-45P is Polyphenylene sulfide (PPS resin).

Dimensions and Weights

GD-45

Nominal size	d	L	H1	H	Weight (kg)
15A	Rc 1/2	111	47	216	3.2
20A	Rc 3/4	111	47	216	3.2
25A	Rc 1	111	47	216	3.2

GD-45P

Nominal size	d	L	H1	H	Weight (kg)
15A	Rc 1/2	111	47	213	3.2
20A	Rc 3/4	111	47	213	3.2
25A	Rc 1	111	47	213	3.2

Nominal Size Selection Chart

Example: When selecting the nominal size of a pressure reducing valve whose inlet pressure (P1), reduced pressure (P2), and flow rate are 1.3 MPa, 0.6 MPa, and 200 kg/h, respectively, first find the intersection point of the inlet pressure of 1.3 MPa and the reduced pressure of 0.6 MPa. Trace down vertically from this intersection point to find the nominal size with a flow rate of 200 kg/h or over. In this case, the nominal size is 20A. (Set the safety factor at 80 to 90%.)

Operation

When the adjusting screw is turned clockwise to compress the spring, the bellows are extended and the spindle opens the valve. When the valve opens, the steam flowing to the outlet side passes through the reduced pressure detection hole, becomes an upwardly directed pressure under the bellows, and balances the force of the spring. The degree of valve opening is adjusted by the balancing of inlet and reduced pressures, thereby stabilizing reduced pressure.

No.	Parts Name	No.	Parts Name
1	Body	8	Spindle
2	Spring Chamber	11	Bellows
3	Cap	14	Adjusting Spring
4	Valve Seat	16	Adjusting Screw
5	Valve	18	Bolts
6	Valve Spring	20	Handle (Only GD-45P)
7	Screen

Installation Example

Installation Precautions

• In case installing a safety valve as a safety device at the outlet side, joint a relief pipe at the outlet of the safety valve and guide it to a safe place where steam can relieve out to prevent burns.
• Do not disassemble the valve unreasonably.
• Remove foreign matter and scales from the lines before connecting the valve.
• Install a strainer (80 mesh) at the valve inlet side.
• Install a safety valve at the valve outlet side as a safety device for equipment.
• Install a pressure gauge at both the inlet and outlet sides of the valve.
• Install a steam trap to the inlet side of the valve to prevent drainage problems.
• When installing quick open and close valves, such as a solenoid valve, install it at the inlet side as much as possible, and secure at least 3 m from the valve.
• When pressure reducing in two stages, secure at least 3 m between the valves.
• Provide space on the top and bottom of the valve so that the valve can be easily disassembled and inspected.

Adjustment Procedure

Follow the steps below, and slowly turn the adjusting screw/handle to set the pressure. Incorrect adjustment may cause hunting or water hammer.

Adjusting procedure for GD-45P:

1. Close the stop valve at the inlet and outlet side of the pressure reducing valve, and taking sufficient time not to blow the safety valve, blow off the fluid to remove foreign matter via the by-pass line. After blowing, close the by-pass line stop valve.
2. Slowly open the stop valve at the inlet side of the pressure reducing valve, and adjust the travel of the stop valve at the outlet side of the pressure reducing valve so that a little fluid flows.
3. Press and slowly turn the handle until the pressure is adjusted to the desired level checking the pressure gauge mounted on the outlet side. Turn the handle clockwise to increase, and counterclockwise to decrease the pressure.
4. Slowly open the stop valve at the outlet side, and make fine adjustments to the reduced pressure.

Handle Operation (GD-45P)

Press and turn the handle. The handle usually does not rotate due to the stopper. Do not force it to turn or it may get damaged. Do not use tools to turn the handle. The rotation range of the handle is limited.

Troubleshooting

Problem	Cause	Solution
Pressure does not rise to the desired level.	Incorrect pressure is being used. Nominal size is too small. Incorrect adjustment. Strainer or screen is clogged. Pressure gauge malfunction.	Correct the pressure. Replace with correct nominal size. Re-adjust. Disassemble and clean. Replace the pressure gauge.
Reduced pressure exceeds prescribed level.	Foreign matter is embedded in the valve/valve seat. Reduced pressure sensing hole is clogged. By-pass valve is leaking.	Disassemble and clean. Polish scratches if they exist. Disassemble and clean. Repair or replace the valve.
Abnormal noise is heard.	Pressure reduction ratio is too large. Drainage problem. Abrupt open/close valve is located too close.	Use a two-stage reduction. Install a trap. Increase distance between valves.