Yoshitake GD-26S series pressure reducing valves are designed for cold and hot water applications. The wetted parts are made of cast stainless steel (corrosion-resistant material) to prevent rusty water, making them suitable for environments where clean water is essential. The series includes the GD-26S, GD-26S-NE, GD-27S, GD-27S-NE, GD-28S, GD-29S, and GD-29S-NE models.

Features

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

Specifications

Model	GD-26S, GD-26S-NE, GD-27S, GD-27S-NE	GD-28S, GD-29S, GD-28S-NE, GD-29S-NE
Application	Cold and hot water	Cold and hot water
Inlet pressure	1.0 MPa or less	1.6 MPa or less (2.0 MPa or less for some variants)
Reduced pressure	(A) 0.05-0.35 MPa (B) 0.3-0.7 MPa	(A) 0.2-0.35 MPa (GD-28S) (B) 0.3-0.7 MPa
Minimum differential pressure	0.05 MPa	0.05 MPa
Maximum pressure reduction ratio	10:1	7:1 (for GD-28S/29S)
Application temperature	5-90℃	5-90℃
Body / Valve seat material	Cast stainless steel	Cast stainless steel
Valve disc / Diaphragm	EPDM or FKM / EPDM	EPDM
Connection	JIS Rc screwed / JIS 10K FF flanged	JIS Rc screwed / JIS 16K/20K FF flanged

INFO

• A strainer (40 mesh) is incorporated in 15A to 50A. 65A to 150A do not include a strainer.
• Available with FKM (Except GD-26S-NE and GD-27S-NE).

Dimensions and Weights

GD-26S, GD-26S-NE, and GD-28S (JIS Rc screwed)

Nominal size	d	L	H	H1	Weight (kg)
20A	Rc 3/4	135	170	41	2.2 (2.3)
25A	Rc 1	135	170	41	2.2 (2.3)
32A	Rc 1-1/4	180	224	57	4.7 (4.9)
40A	Rc 1-1/2	180	224	57	4.5 (4.7)
50A	Rc 2	200	239.5	61	6.5 (6.7)

The values in parentheses are for GD-28S-NE.

GD-27S, GD-27S-NE, and GD-29S (Flanged)

Nominal size	L	H	H1	Weight (kg)
20A	160	170	41	3.9
25A	160	170	41	4.8
32A	200	224	57	8.0
40A	200	224	57	8.3
50A	220	239.5	61	10.8
65A	220	329	77	20.6
80A	230 (234)	345	82	22.0 (25.0)
100A	270 (278)	412	94	34.5 (36.5)

The values in parentheses are the dimensions and weights of the GD-29S.

Rated Flow Rate

If the differential pressure before and after the valve is 0.15 MPa or more:

Nominal size	15A	20A	25A	32A	40A	50A	65A	80A	100A	125A	150A
Rated flow (L/min)	30	40	60	100	150	250	300	450	700	1,600	1,800

If the differential pressure is less than 0.15 MPa, select the nominal size from the flow rate charts.

Flow and Pressure Characteristics

Flow Rate Charts

Nominal size: 15A to 50A

Nominal size: 65A to 100A

Pressure Characteristic Chart

This chart shows variation in reduced pressure when the inlet pressure of 0.6 MPa is changed between 0.15 MPa and 1.0 MPa while the reduced pressure is set at 0.1 MPa.

Installation and Piping

TIP

• Install a strainer on the inlet side of the pressure reducing valve of the nominal size 65A to 150A.
• The product can be installed either horizontally or vertically (nominal size 15A to 100A). For sizes 125A and 150A, install horizontally.
• Be sure to install pressure gauges at the inlet and outlet sides of the product for correct pressure adjustment.

WARNING

Before installing the product in the piping, be sure to remove foreign substances and scale from the piping completely. Ingress of foreign substances or scale into the product leads to valve leakage or malfunction.

Adjusting Procedure

1. Close the stop valves at the inlet and outlet sides of the reducing valve, and take adequate time to blow out fluid by using a bypass line.
2. Fully open the stop valve at the inlet side slowly, and open the stop valve at the outlet side so that a little fluid can flow through.
3. Remove the domed cap nut and turn the adjusting screw while watching the pressure gauge at the outlet side.
   • Turn the adjusting screw to the right (clockwise) to increase the reduced pressure.
   • Turn the adjusting screw to the left (counterclockwise) to decrease the reduced pressure.
4. Fully open the stop valve at the outlet side slowly.
5. After the adjustment is complete, tighten the domed cap nut.

Disassembly and Maintenance

DANGER

Completely discharge the pressure inside of the product, piping, and equipment before disassembly and inspection. Failure to follow this notice may result in scalds or injury due to the residual pressure.

1. Remove the domed cap nut, turn the adjusting screw counterclockwise, and set the spring free (no load).
2. Remove the bolts of the spring chamber and remove the spring chamber. Then take out the spring and the spring plate.
3. Remove the nut, and then the diaphragm retainer and diaphragm.
4. Remove the set screws (or bolts) of the valve seat, and remove a set of the valve seat (valve seat, spindle, disc, and O-ring).
5. Secure the spindle, loosen the U-nut, and remove the disc and O-ring.

Clean the strainer regularly at least once or twice a year to prevent flow rate decrease and product malfunction.