Yoshitake GP-1001 is a pilot-operated pressure reducing valve designed for steam applications, uniquely equipped with a manual handle for straightforward pressure adjustment. It features a ductile cast iron body and a spherical main valve that offers excellent sealability, greatly reducing valve seat leakage (compliant with ANSI Class IV). This model is highly suitable for building utilities, air-conditioning systems, and factory systems where precise steam pressure control and frequent manual adjustments are required.

Features

• Significantly improved workability and durability compared with conventional pressure reducing valves.
• Spherical main valve offers great sealability and reduction of valve seat leakage (0.01% or less of rated flow).
• Compliant with SHASE-S106 Pressure Reducing Valves (by the Society of Heating, Air-Conditioning and Sanitary Engineers of Japan).
• Simple and robust internal structure.
• Equipped with an adjusting handle for convenient manual operation.

Specifications

Specification	Value
Application	Steam
Inlet Pressure	0.1–1.0 MPa
Reduced Pressure	0.05–0.9 MPa (90% or less of inlet pressure)
Minimum Differential Pressure	0.05 MPa
Maximum Pressure Reduction Ratio	20:1
Maximum Temperature	220°C
Valve Seat Leakage	0.01% or less of rated flow
Body Material	Ductile cast iron
Valve / Valve Seat Material	Stainless steel
Piston / Cylinder Material	Brass or bronze
Connection	JIS 10K FF flanged

Dimensions and Weights

Nominal Size	L (mm)	H1 (mm)	H (mm)	Weight (kg)
15A	150	64	285	8.0
20A	155	64	285	8.5
25A	160	67	300	10.0
32A	190	82	323	14.0
40A	190	82	323	14.5
50A	220	93	347	20.0
65A	245	100	357	30.0
80A	290	122	404	35.0
100A	330	144	450	52.5

Operation

The pressure-reducing valve reduces pressure by throttling the valve. It is composed of a main valve and main valve seat for throttling, along with an adjusting spring, diaphragm, pilot valve, and piston for pressure sensing and activation.

1. When mounted correctly, releasing the compression of the adjusting spring allows the spring to close the main valve and pilot valve. Slowly open the gate valve to allow high-pressure fluid in. Inlet pressure is applied to the downside of the main valve and, via the strainer and inlet pressure passage, to the downside of the pilot valve.
2. Turning the adjusting screw (via the handle) clockwise compresses the spring, which flexes the diaphragm to open the pilot valve.
3. Inlet pressure enters the upside of the piston. This pressure overrides the pressure on the downside of the main valve and the main valve spring load, opening the main valve. Fluid begins to flow.
4. Reduced pressure is led to the diaphragm chamber via the sensing port. The diaphragm balances this pressure with the adjusting spring load to control the pilot valve travel.
5. Changes in pilot valve travel adjust the fluid flow to the upside of the piston, regulating main valve travel to maintain the appropriate reduced pressure.

Selection Method

Specifications Selection Chart

Find the intersection point of the inlet and reduced pressures. The valve is suitable if the point falls within the indicated range.

Characteristics

Flow Rate Characteristics

• Shut-off pressure raise: 0.02 MPa or less
• Offset: 0.03 MPa or less (Setting pressure: 0.03~0.1 MPa) / 0.05 MPa or less (Setting pressure: 0.1~1.4 MPa)

Pressure Characteristics The chart indicates variation in reduced pressure when the inlet pressure changes from 1.6 to 0.3 MPa, with reduced pressure set to 0.1 MPa at an inlet of 1.0 MPa.

Nominal Size Selection

If the inlet pressure exceeds 0.7 MPa and the reduced pressure is 0.4 MPa or less, find the appropriate correction coefficient C using the chart below, and multiply the rated Cv value to obtain the corrected Cv value.

Installation

Example of Piping

Installation Precautions

• Due to heavy weight, hold the valve with lifting equipment while piping to prevent injury.
• Install a safety valve at the outlet side as a safety device for equipment. Guide the relief pipe to a safe location to prevent burns from blown-off steam.
• Install a strainer (80-100 mesh or equivalent) at the valve inlet side to prevent debris from affecting pressure control.
• Install a pressure gauge at both the inlet and outlet sides of the valve for correct adjustment.
• Install a steam trap at the inlet side to prevent drainage problems.
• Provide a by-pass line.

Provide space on the top and bottom of the valve so that it can be easily disassembled and inspected.

Maintenance

Operation Notes

Close the stop valves before and after the valve, and remove all foreign matter and scales via the by-pass line before operation. For the model with a handle, be sure to operate the handle manually and turn it while pushing down. Do not turn with too much torque or excessively.

Troubleshooting

Problem	Possible Cause	Countermeasure
Desired pressure cannot be reached	1. Inappropriate operating pressure. 2. Strainer clogged. 3. Foreign matter on piston/cylinder. 4. Damaged piston ring. 5. Nominal size too small.	1. Adjust to proper value. 2. Disassemble and clean. 3. Remove foreign matter or replace parts. 4. Replace piston ring. 5. Change to suitable nominal size.
Secondary pressure rises above set value	1. Foreign matter on main valve/seat. 2. Foreign matter on pilot valve/seat. 3. Piston/cylinder obstructed. 4. No steam trap at line end. 5. By-pass valve leaking. 6. Diaphragm damaged.	1. Clean or replace parts. 2. Clean or replace pilot valve unit. 3. Remove foreign matter. 4. Install a steam trap. 5. Repair or replace. 6. Replace diaphragm.
External leakage	Gasket damaged/deteriorated or diaphragm broken.	Replace gasket or diaphragm.
Abnormal noise	1. Flow rate too low. 2. High pressure reduction ratio. 3. Condensate problem.	1. Choose a proper nominal size. 2. Use two-stage reduction. 3. Install a steam trap.

Exploded Drawing