Yoshitake GD-28-NE is a direct-acting pressure reducing valve designed for cold and hot water applications. It features a corrosion-resistant cast bronze body (NPb-treated) and is capable of handling inlet pressures up to 1.6 MPa. The valve incorporates a built-in 40-mesh strainer and utilizes a pressure balance structure to maintain a constant reduced pressure regardless of inlet pressure fluctuations. It is widely used in building services and industrial water systems where reliable pressure control and low noise operation are required.

Features

1. Wetted parts are made of corrosion-resistant material to prevent rusty water.
2. Reduced noise design.
3. Pressure balance structure can keep the reduced pressure at a constant level without being affected by inlet pressure.
4. Closed structure keeps fluid inside even if the diaphragm is damaged or broken.
5. Maintenance and inspection can be conducted easily by disassembling the upper side only.
6. Compact and lightweight design makes piping works easy.

Specifications

Specification	Value
Model	GD-28-NE
Nominal size	15A - 50A
Application	Cold and hot water
Inlet pressure	1.6 MPa or less
Reduced pressure	(A) 0.05 - 0.35 MPa (B) 0.30 - 0.70 MPa
Min. differential pressure	0.05 MPa
Max. pressure reduction ratio	10:1
Application temperature	5 - 90°C
Body / Valve seat	Cast Bronze (NPb-treated)
Valve disc	FKM
Diaphragm	EPDM
Connection	JIS Rc screwed

INFO

• A strainer (40 mesh) is incorporated in 15A to 50A models.
• Pressure gauge connection port is JIS Rc 1/8. The maximum temperature of the pressure gauge is 45°C. If the fluid temperature exceeds 45°C, please protect the pressure gauge by using a siphon tube or similar.
• Conforms to the standard of the Japanese Water Supply Act (JWWA approval).

Dimensions and Weights

Nominal size	d	L (mm)	H (mm)	H1 (mm)	Weight (kg)
15A	Rc 1/2	115	159.5	37.5	1.6
20A	Rc 3/4	120	159.5	38.5	1.7
25A	Rc 1	135	170	41	2.1
32A	Rc 1-1/4	180	224	57	4.0
40A	Rc 1-1/2	180	224	57	4.4
50A	Rc 2	200	239.5	61	6.5

Rated Flow Rate

If the differential pressure before and after the valve is 0.15 MPa or more, choose the nominal size from the rated flow table below:

Nominal size	15A	20A	25A	32A	40A	50A
Rated flow rate (L/min)	30	40	60	100	150	250

If the differential pressure is less than 0.15 MPa, select a proper nominal size from the appropriate chart shown below:

Installation

Piping Example

WARNING

• When installing a safety relief valve for equipment protection at the outlet side of the product, connect a blow-off pipe to the outlet side of the safety relief valve, and lead it to a place where there is no risk of physical damage even if fluid blows out.
• Before installing the product in the piping, be sure to remove foreign substances and scale from the piping. Keep foreign substances from entering the piping, including seal tape or liquid seal agent for piping connection.

TIP

• Install a safety relief valve for equipment protection at the outlet side of the product.
• Be sure to install pressure gauges at the inlet and outlet sides of the product.
• If a quick operating valve such as a solenoid valve is installed, place it at a distance of at least 3 meters from the product.
• The product can be installed either horizontally or vertically (nominal size 15A to 50A).
• It is recommended to use a bronze or stainless-steel nipple for the outlet side of the GD-28-NE when installing to prevent corrosion (rust tubercle) that could clog the reduced pressure detection hole.

Maintenance and Troubleshooting

Troubleshooting

Trouble	Cause	Remedy
Abnormal pressure rises at the outlet side.	1. Foreign substances stuck between the disc and the valve seat, or scratch on them. 2. The O-ring is damaged. 3. The diaphragm is damaged. 4. Leakage from the globe valve of the by-pass line.	1. Disassemble the product and remove the foreign substances. If scratch is observed, replace it. 2. Replace the O-ring. 3. Replace the diaphragm. 4. Repair or replace the globe valve.
Reduced pressure does not reach the desired value.	1. The working pressure is improper. 2. The nominal size of the product is too small for the flow rate. 3. Pressure adjustment is improper. 4. Built-in strainer is clogged.	1. Correct the working pressure. 2. Replace the product with the proper nominal size. 3. Readjust the pressure. 4. Clean the strainer.
Outside leakage	1. Bolt is loosened. 2. O-ring is damaged. 3. Strainer cap or plug is loosened.	1. Tighten the bolts. 2. Replace the O-ring. 3. Tighten the strainer cap or plug.
Abnormal sound	1. The nominal size is too large for the system. 2. The pressure reduction ratio is too large. 3. Air binding has occurred. 4. A quick operating valve is located near the product.	1. Replace with proper nominal size. 2. Reduce pressure in two stages. 3. Install an air vent device. 4. Keep a distance of at least 3 m.

Strainer Cleaning Procedure

Clean the strainer regularly at least once or twice a year. Too much deposit of scales decreases the flow rate, which prevents the product from functioning properly.

1. Close the stop valve at the inlet side and open the stop valve at the end, and remove the internal pressure from the product completely.
2. Turn the strainer cap counterclockwise, and remove it.
3. Remove the strainer from the strainer cap, and wash it in water, and remove deposited scale.
4. After cleaning, reinstall the strainer and strainer cap in the body.
5. Open the stop valve at the inlet side, and check that there is no leakage from the strainer cap. When there is a leakage, replace the O-ring.
6. Open the stop valve at the end, and check that the product operates normally.