Fushiman RMD31 type back pressure valve for liquids

Model	Nominal diameter	Primary measurement pressure range	Maximum operating temperature	Body Material	Connection
RMD31	15–150	0.035 to 0.7 MPa (see catalogue)	80°C	FC,, SCPH, SCS	Flanges

The system adopts the outlet pressure balance method, so fluctuations in the outlet side pressure hardly affect the primary side pressure.
The valve body uses synthetic rubber, ensuring excellent sealing performance when the valve is closed.

Specifications and Materials

Fluid	Nominal Diameter	Primary Side Pressure Range (MPa)	Temperature (℃)	Main Component Materials				Pipe Connection
				Valve Body Spring Cover	Valve Element Diaphragm	Valve Seat Liner	Valve Stem
Air and other non-corrosive gases	15–80	0.035–0.3 0.2–0.7	0–80	Cast Iron	Synthetic Rubber	Bronze	Stainless Steel	Flange JIS 10K Full-Face
	100	0.035–0.3 0.2–0.55
	125・150	0.035–0.4

Notes:

Manufacturers can produce valve boxes from cast iron or stainless steel, and in this case, they can also manufacture ASME Class 150.
They can also manufacture valve boxes with a nylon coating for temperatures of 60°C or lower.
They can produce products for applications where rubber cannot be used in the fluid and brass is not allowed.
They can also manufacture products that exceed the specified pressure range.

Performance

Minimum Differential Pressure Setting	0.02 MPa
Offset	0.06 MPa (For nominal diameters 15–40, 65, 125, 150) 0.08 MPa (For nominal diameters 50, 80, 100)
Shutoff Pressure Drop	0.01–0.02 MPa
Minimum Adjustable Flow Rate (Water) (¹)	3–5 L/min
Valve Leakage	0.01% or less of the rated flow rate
Maximum Usable Viscosity	400 mm²/s (under operating temperature conditions)

Note (¹): For liquids other than water, divide by √γ (γ = specific gravity of the liquid, assuming water at 4°C as 1).

Cv Value

Nominal Diameter	15–25	32	40	50	65	80	100	125	150
Cv	3.9	6.3	8.3	13	21	29	50	76	109
Maximum Flow Rate (Water) (L/min) (²)	90	150	204	330	543	767	1323	2016	2892

Note (²): For liquids other than water, divide by √γ (γ = specific gravity of the liquid, assuming water at 4°C as 1).

Structure and Dimensions

Dimensions and Weight

Nominal Diameter	Cast Iron Valve Box					Cast Steel or Stainless Steel Valve Box
Nominal Diameter	L	H₁	H₂	E	Weight	L	H₁	H₂	E	Weight
15	196	70	317	155	12	206	70	317	155	16
20	200	70	317	155	13	210	70	317	155	17
25	200	70	317	155	13	210	70	317	155	17
32	175	70	317	155	14	220	70	317	155	18
40	190	80	325	155	16	230	80	325	155	20
50	195	80	325	155	17	225	80	325	155	22
65	230	104	425	210	34	280	104	425	210	38
80	250	127	460	250	45	290	127	460	250	50
100	290	127	460	250	58	330	127	460	250	65
125	365	174	607	320	98	380	174	607	320	130
150	415	207	787	380	159	470	207	787	380	170

RMD31

Nominal Diameter Selection

Select the appropriate nominal diameter using the nominal diameter selection chart. If the viscosity exceeds 20 mm²/s, consider the flow rate adjusted for viscosity correction as shown below when making your selection.
If the set pressure and outlet-side pressure are not constant within a certain range, select the nominal diameter based on the minimum differential pressure, which is determined by the set pressure and outlet-side pressure.
If the differential pressure is less than 0.1 MPa, add the offset value to the differential pressure when selecting the nominal diameter. Avoid selecting an excessively large back pressure valve, as this is more economical.

Disassembly and Maintenance Space Requirements

Nominal Diameter	15–32	40・50	65・80	100	125	150
Upward Space from Pipe Center (mm)	470	480	640	730	930	1220

Piping Example

It can be installed and used on both horizontal and vertical piping. However, for hot water, there is a risk of air blockage, so it cannot be used in a vertical pipe with an upward flow direction from the bottom.
It is recommended to install a straight pipe section of at least 300 mm (for nominal diameters 15–25), 600 mm (for nominal diameters 32–40), 900 mm (for nominal diameters 50–100), and 1200 mm (for nominal diameters 125–150) before and after the back pressure valve as much as possible. This will ensure more stable operation.