The Yoshitake GD-400SS is a direct-acting pressure reducing valve constructed from cast stainless steel (SCS14), designed for air and nitrogen gas applications. It maintains a constant reduced pressure without being affected by inlet pressure variations, utilizing a large pressure sensing diaphragm for accurate set pressure control. The valve features a simple structure for easy maintenance and supports a high maximum pressure reduction ratio of 400:1.

Features

1. Pressure balance structure can keep the reduced pressure at a constant level without being affected by inlet pressure.
2. Due to simple structure, disassembly and maintenance can be conducted easily.
3. Wide range of use due to high maximum pressure ratio.
4. Diaphragm with a large pressure sensing area has accuracy to high set pressure.

Specifications

Model	GD-400SS
Nominal size	15-50A
Application	Air, Nitrogen gas *1
Inlet pressure	2.5-400 kPa
Reduced pressure	(A) 0.5-1.4 kPa (B) 1.2-3.3 kPa (C) 3.0-8.0 kPa (D) 7.0-20 kPa
Working temperature	5-60℃
Minimum differential pressure	2.0 kPa
Maximum pressure reduction ratio	400:1
Reduced pressure detection method	External sensing *2
Minimum adjustable flow rate	15-25A: 1.2 m³/h (standard condition) 32-50A: 10.0 m³/h (standard condition)
Material: Body	Cast stainless steel (SCS14)
Material: Valve / Valve seat / Spindle	Stainless steel
Material: Disc / Diaphragm	NBR *3
Connection	JIS 10K FF Flanged

• *1 Please contact us when using for other fluids.
• *2 For GD-400SS, please prepare a conduit and a joint for external sensing at your end.
• *3 Available with FKM type.
• *4 Use on a compressed air system with dry air from oil-free compressors may cause deterioration of rubber parts in a very short time (ozone crack). Please consult with us before such installation.

Dimensions and Weights

Nominal size	L	H1	H	Weight
15A	166	86	526	32.0 kg
20A	170	86	526	32.0 kg
25A	170	86	526	33.0 kg
32A	180	96	561	34.0 kg
40A	180	96	561	34.0 kg
50A	180	101	561	35.0 kg

(Note: Dimensions are in mm. Weights shown are for the GD-400SS type).

15A-25A

32A-50A

Characteristics

Flow Characteristic Chart

15-25A: 1.2 m³/h (standard condition) / 32-50A: 10.0 m³/h (standard condition)

Pressure Characteristic Chart

Specifications Chart

This chart shows variation in reduced pressure when the inlet pressure of 400 kPa is changed to 10 kPa while the reduced pressure is set at 8.0 kPa.

Piping Diagram Example

Precautions

1. Connect the external sensing part to the outlet side.
2. Do not adjust needle valve of the pressure reducing valve unreasonably.
3. Make sure to use a pipe with a diameter that can keep the inside flow velocity between 5 m/s and 15 m/s for outlet side.
4. When performing pressure test or airtight test after connected to the piping, apply the airtest pressure specified in the table below.

If pressure beyond the specified airtest pressure is applied, internal parts may be damaged.

Airtight test	Airtight test pressure
Inlet pressure	400 kPa or less
Reduced pressure	Spring range A	1.8 kPa or less
Reduced pressure	Spring range B	4.2 kPa or less
Reduced pressure	Spring range C	10 kPa or less
Reduced pressure	Spring range D	25 kPa or less

Chart for Selecting Nominal Sizes

When the inlet pressure is between 2.5 kPa and 200 kPa (Fluid: 20°C Air)

Selection Example

When selecting the nominal size of a pressure reducing valve whose inlet pressure (P1), reduced pressure (P2), and flow rate are 10 kPa, 3 kPa, and 15 m³/h (standard condition), respectively: First find intersection point (a) of the inlet pressure of 10 kPa and the reduced pressure of 3 kPa. Trace down vertically from this intersection point to find intersection point (b) with the flow rate of 15 m³/h (standard condition). Since intersection point (b) lies between nominal sizes 20A and 25A, select the larger one, 25A.

*Set the safety factor at 80 to 90%.

When the inlet pressure is between 200 kPa and 400 kPa

Nominal size	Inlet pressure (kPa)	Rated flow rate (m³/h [standard condition])	Rated flow rate (m³/h [standard condition])
		Reduced pressure: 0.5-4 kPa	Reduced pressure: 4-20 kPa
15A	200-400	60	60
20A	200-300	90	90
20A	300-400	90	120
25A	200-300	120	120
25A	300-400	120	150
25A	400	120	190
32A	200-300	200	250
32A	300-400	200	300
40A	200-300	250	275
40A	300-400	250	325
50A	200-300	325 [275]	375 [325]
50A	300-400	325 [275]	425 [375]

(Note: The values in brackets [] are the flow rates for the FKM type).