Manufacturer:  Fushiman Co.,LTD.
Model: RMD31P/LP And RLG61-2P

RMD31P Type Back Pressure Valve for Gas

Model	Nominal Diameter	Primary Pressure Setting Range	Max Operating Temperature	Body Material	Connection
RMD31P	15～100	0.035～0.7MPa	80℃	FC	Flange

RMD31LP Type Back Pressure Valve for Gas

Model	Nominal Diameter	Primary Pressure Setting Range	Max Operating Temperature	Body Material	Connection
RMD31LP	15～100	0.01～0.05MPa	80℃	FC	Flange

RLG61-2P Type Back Pressure Valve for Gas

Model	Nominal Diameter	Primary Pressure Setting Range	Max Operating Temperature	Body Material	Connection
RLG61-2P	15〜50	0.5～20kPa	80℃	FC	Flange

RMD31P Type Back Pressure Valve for Liquid

Model	Nominal Diameter	Primary Pressure Setting Range	Max Operating Temperature	Body Material	Connection
RMD31P	15〜100	0.035～0.7MPa	80℃	FC	Flange

New Product

• Maintains the characteristics of a self-operated valve that accurately controls load fluctuations while achieving an offset comparable to other valves.
• Compared to conventional products, an increase in nominal flow rate (Cv value) can be expected. (Note: The Cv value depends on factors such as pipe flow velocity and remains the same for certain types and sizes as previous products.)
• Can be installed on existing valves, allowing for an easy performance upgrade.
• Useful when replacing existing self-operated valves while maintaining tuning accuracy in large-scale systems.
• Versatile, supporting both low-pressure applications and compressed air control via a pressure-reducing valve.

The Hybrid Back-Pressure Valve achieves high precision comparable to other control valves by simply adding a newly designed pilot controller to a standard self-operated back-pressure valve.

A conventional self-operated back-pressure valve may have offset issues and insufficient adjustment accuracy, and control using other types of regulating valves for primary-side pressure control may complicate system configurations.

For applications requiring high-precision primary pressure control with a simpler system setup, the Hybrid Back-Pressure Valve is the optimal solution.

1. Type of Equipment

1.1 Hybrid Back-Pressure Valve

1.2 CP1-Type Pilot Controller (PC)

2. Operation Description

1. The Hybrid (HB) Back-Pressure Valve consists of two components:

   • The main valve, which controls pressure.
   • The pilot controller (PC), which adjusts the operating fluid based on changes in primary-side pressure.
   • The pilot controller is supplied with an operating fluid, such as compressed air, and its outlet is connected to the spring chamber of the main valve.

2. The main valve automatically adjusts the valve opening in response to primary-side pressure, similar to a standard back-pressure valve.

   • However, the spring force varies depending on the valve opening (large when fully open, small when slightly open), which causes offset.

3. The pilot controller operates as follows:

   • When primary pressure is high, it opens and releases the operating fluid externally.
   • When primary pressure is low, it closes and sends the operating fluid to the spring chamber.
   • The main valve and the pilot controller operate almost simultaneously, ensuring that primary-side pressure remains stable even when load fluctuations occur.

3. Specifications and Materials

Hybrid Back-Pressure Valve Model		RMD31P	RMD31LP	RLG61-2P
Main Valve Section	Model	RMD31	RMD31L	RLG61-2
	Fluid	Gas & Liquid	Gas
	Nominal Diameter	15–100		15–50
	Set Pressure Range	15–80A: 0.035–0.3, 0.2–0.7 MPa 100A: 0.035–0.3, 0.2–0.55 MPa	10–50 kPa	0.5–1.4, 1.2–3.3, 3.0–8.0, 7.0–20 kPa
	Temperature	0–80°C
	Major Materials	Refer to the catalog for main valve materials.
PC Section	Operating Fluid	Air
	Operating Pressure	140–250 kPa	100 kPa	20–40 kPa
	Air Consumption	Approx. 200 ℓ/h (Standard Condition)		Approx. 40 ℓ/h (Standard Condition)
	Connection Port	JIS Rc 1/4 (Threaded)
	Major Materials	Body & Valve: Stainless Steel, Spring Protection Tube: Aluminum Alloy, Diaphragm: Synthetic Rubber, Orifice Valve & Piping: Copper Alloy

Note (1): The operating pressure varies depending on the set pressure.

4. Performance and Cv Value

Hybrid Back-Pressure Valve Model		RMD31P (RMD31LP)									RLG61-2P
Nominal Diameter		15	20	25	32	40	50	65	80	100	15	20	25	32	40	50
Cv Value		4.5	4.5	4.5	7.0	10.1	18	28.1	35	55	1.8	2.6	3.9	6.3	8.3	13
Performance	Minimum Differential Pressure	10 kPa (10 kPa)									0.5 kPa
	Offset	30 kPa or less (3 kPa or less)						30 kPa or less (3 kPa or less)			0.1 kPa or less
	Shutoff Pressure Drop	10 kPa or less (3 kPa or less)						10 kPa or less (5 kPa or less)			0.2 kPa or less
	Minimum Adjustable Flow Rate	Refer to the main valve catalog.
	Seat Leakage	0.01% or less of the rated valve flow

Note (2): The values may vary depending on the set pressure and the piping conditions before and after the valve.
Note (3): The values may increase depending on the main valve settings.

5. Structure, Dimensions, and Mass

5.1 Structure, Dimensions, and Mass of RMD31P and RMD31LP Back-Pressure Valves

Dimensions and Mass (mm, kg)

Nominal Diameter	L	Hi	h2		h3	E	Fi	f2	f3	Weight	Main Valve: Pipe Connection, Valve Body Material: Cast Iron
			RMD31P	RMD31LP
15	196	70	317	363	165	155	88	128	159	15	Flange Type JIS10K Full Face
20	200	70	317	363	165	155	88	128	159	16
25	200	70	317	363	165	155	88	128	159	16
32	175	70	317	363	165	155	88	128	159	17
40	190	80	325	371	175	155	88	128	159	19
50	195	80	325	371	175	155	88	128	159	20
65	230	104	425	484	254	210	109	156	180	37
80	250	104	425	484	254	210	109	156	180	38
100	290	127	460	533	289	250	126	176	197	61

Note: We also manufacture valve bodies made of cast bronze or cast stainless steel.

5.2 Structure, Dimensions, and Mass of RLG61-2P Type Back Pressure Valve

Dimensions and Mass (mm, kg)

Nominal Diameter	L	Hi	h2	h3	H4	Mass	Main Valve: Pipe Connection, Valve Body Material: Cast Iron
15	180	81	451	25	298	23.5	Flange Type JIS10K Full Face
20	185	81	451	25	298	23.5
25	196	84	455	30	302	25
32	220	92	478	53	325	28
40	220	92	478	53	325	29
50	230	92	478	53	325	30

Note: The valve body material can be made of cast bronze or stainless steel cast steel.

6. Piping Example

(mm)

Nominal Diameter	15–32	40 • 50	65 • 80	100
Above Pipe Center	520	530	650	720
Below Pipe Center	190	200	340	400

(mm)

Nominal Diameter	15–50
Above Pipe Center	520
Below Pipe Center	190

7. Precautions for Use

● Before using, be sure to read the “Instruction Manual” carefully.
● Before connecting the operation air piping, always blow it out to remove dust (scale) and other debris completely.
● The pilot controller (PC) should be supplied with a constant pressure of operating air through a pressure-reducing valve with a filter.
● Ensure that the exhaust port of the pilot controller is not blocked.
● When using the RMD31P model for liquids, make sure to completely discharge the air retained inside at the beginning of water flow.