DFT: Check Valves:

Restrictor Threaded In-Line Check Valve

Spring-assisted, in-line check valve for applications that require higher cracking pressures.
Cracking pressures are available from 2 to 40 psi.
The Restrictor Check Valve should not be considered a substitute for a Pressure Relief Valve.
The Restrictor Check Valve provides reliable, low maintenance service for a wide range of fluids and gases.
The valve consists of a guard cage, spring, valve disc, retaining ring and seat.

Documentation:
Product Specifications
(142KB PDF)

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Check Valve Operation:

A check valve allows flow in one direction and automatically prevents back flow (reverse flow) when fluid in the line reverses direction. They are one of the few self-automated valves that do not require assistance to open and close.

Check valves are flow sensitive and rely on the line fluid to open and close. The internal disc allows flow to pass forward, which opens the valve. The disc begins closing the valve as forward flow decreases or is reversed, depending on the design. The function or purpose of a check valve is to prevent reverse flow.

Internal sealing of the check valve disc and seat relies on “reverse” line pressure as opposed to the mechanical force used for on/off valves. Because of this, allowable seat leakage rates are greater for check valves than with on/off valves.

Factors affecting check valve seat leakage include reverse pressure, medium, and what the seat material is made of, such as metal or elastomer. Metal sealing surfaces generally will allow some leakage while elastomers such as Buna-N and Viton provide bubble-tight shutoff (zero leakage).

The longest trouble-free service will come from valves sized for the application, not the line size, whereby the disc is stable against the internal stop in the open position or fully closed. When these conditions are met, no fluttering of the disc will occur (resulting in premature failure.)

Check valve internals are flow sensitive. If there is not enough flow disc movement occurs inside the valve resulting in wear, potential failure, and a higher pressure drop than calculated.

DFT Restrictor Threaded In-Line Check Valve

Restrictor Check Valve

Higher cracking pressures
1/4” to 2-1/2” Line size
450 to 2500 CWP
Threaded ends
Stainless steel construction
Spring-assisted silent closing

DFT Restrictor Check Valve
common service installation:

The DFT® Restrictor Check Valve (RCV) is a versatile, all-purpose, spring-assisted, in-line check valve for applications that require higher cracking pressures to open the check valve than those offered by other DFT® check valves.

Cracking pressures are available from 2 to 40 psi. Like the Basic-Check® valve, the Restrictor Check provides reliable, low maintenance service for a wide range of fluids and gases at various pressure/temperature combinations.

It can be combined with pipe fittings such as couplings, drain elbows, etc. (not provided by DFT®) to form a complete check valve unit ideally suited for a broad range of applications. The RCV should not be considered a substitute for a Pressure Relief Valve.

Restrictor Check: Cold, Non-shock Pressure Rating (PSIG)
Size	1/4", 3/8", 1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"
Rated Working Pressure	2500	2000	1500	850	700	450	450

Sat. Steam Pressure (PSIG)	Temperature (°F)	Adjusted Rating as Percent of Cold Rating
-3	200	86%
15	250	82%
52	300	78%
232	400	71%
407	450	69%
665	500	66%
1526	600	62%
3075	700	60%
All stainless steel construction is suitable for cryogenic service. For pressure rating at elevated temperatures for standard metal-seated valves, reduce rating per chart above. Maximum valve temperature rating is limited by soft seat (if any) and spring materials. For ratings of soft seals using some other elastomers, consult DFT.

Restrictor Check
Valve Size	Variable	Spec
1/4"	Dim A	0.25
	Dim B	1
	Weight	0.38
	Cv	5.8
	CP	3.3 to 20.4
3/8"	Dim A	0.38
	Dim B	1
	Weight	0.38
	Cv	5.8
	CP	3.3 to 20.4
1/2"	Dim A	0.50
	Dim B	1
	Weight	0.38
	Cv	5.8
	CP	3.3 to 20.4
3/4"	Dim A	0.75
	Dim B	1.50
	Weight	0.88
	Cv	13.2
	CP	3.3 to 15.5
1"	Dim A	1.00
	Dim B	2.00
	Weight	1.25
	Cv	23.1
	CP	4.2 to 40.7
1-1/4"	Dim A	1.25
	Dim B	2.50
	Weight	2.25
	Cv	36
	CP	1.8 to 18.8
1-1/2"	Dim A	1.50
	Dim B	3.00
	Weight	3.75
	Cv	57.4
	CP	2.4 to 19.1
2"	Dim A	2.00
	Dim B	4.00
	Weight	7.00
	Cv	90
	CP	1.7 to 9.4
2-1/2"	Dim A	2.50
	Dim B	4.00
	Weight	7.00
	Cv	90
	CP	4.6 to 10.8

Materials of Construction
Component	Restrictor Check
Seat	303 SS
Disc	316 SS
Guard	CF8M (3)
Spring	302 SS
Retaining Ring	316 SS
Notes: 1. Contingent on service ratings of matching pipe and fittings. 2. Saturated steam pressure is given for reference only; pressure limit of valve is the adjusted rating at the given temperature. 3. 1/4”, 3/8” and 1/2” BSS units have a 303 SS guard.


RESTRICTOR THREADED IN LINE CHECK VALVES
Part #	Size	Line Size Inlet (FNPT) A	Outside Thread (MNPT) B	Valve Cracking Pressure	Cold Working Pressure
5639	DN 8 0.25 in	0.25 in	1.00 in	3.3 psi 0.228 bar	0 psig 2500 psig 0 barg 172 barg
5640	DN 8 0.25 in	0.25 in	1.00 in	5.32 psi 0.365 bar	0 psig 2500 psig 0 barg 172 barg
5641	DN 8 0.25 in	0.25 in	1.00 in	8.1 psi 0.558 bar	0 psig 2500 psig 0 barg 172 barg
5642	DN 8 0.25 in	0.25 in	1.00 in	10.9 psi 0.752 bar	0 psig 2500 psig 0 barg 172 barg
5650C204	DN 8 0.25 in	0.25 in	1.00 in	20.4 psi 1.407 bar	0 psig 2500 psig 0 barg 172 barg
5643	DN 10 0.375 in	0.375 in	1.00 in	3.3 psi 0.228 bar	0 psig 2500 psig 0 barg 172 barg
5644	DN 10 0.375 in	0.375 in	1.00 in	5.3 psi 0.365 bar	0 psig 2500 psig 0 barg 172 barg
5645	DN 10 0.375 in	0.375 in	1.00 in	8.1 psi 0.558 bar	0 psig 2500 psig 0 barg 172 barg
5646	DN 10 0.375 in	0.375 in	1.00 in	10.9 psi 0.752 bar	0 psig 2500 psig 0 barg 172 barg
5651C204	DN 10 0.375 in	0.375 in	1.00 in	20.4 psi 1.407 bar	0 psig 2500 psig 0 barg 172 barg
5616	DN 15 0.5 in	0.50 in	1.00 in	3.3 psi 0.228 bar	0 psig 2500 psig 0 barg 172 barg
Part #	Size	Line Size Inlet (FNPT) A	Outside Thread (MNPT) B	Valve Cracking Pressure	Cold Working Pressure
5617	DN 15 0.5 in	0.50 in	1.00 in	5.3 psi 0.365 bar	0 psig 2500 psig 0 barg 172 barg
5618	DN 15 0.5 in	0.50 in	1.00 in	8.1 psi 0.558 bar	0 psig 2500 psig 0 barg 172 barg
5619	DN 15 0.5 in	0.50 in	1.00 in	10.9 psi 0.752 bar	0 psig 2500 psig 0 barg 172 barg
5652C204	DN 15 0.5 in	0.50 in	1.00 in	20.4 psi 1.407 bar	0 psig 2500 psig 0 barg 172 barg
5635	DN 20 0.75 in	0.70 in	1.50 in	3.3 psi 0.228 bar	0 psig 2000 psig 0 barg 138 barg
5636	DN 20 0.75 in	0.75 in	1.50 in	5.3 psi 0.365 bar	0 psig 2000 psig 0 barg 138 barg
5637	DN 20 0.75 in	0.75 in	1.50 in	8.4 psi 0.579 bar	0 psig 2000 psig 0 barg 138 barg
5653C155	DN 20 0.75 in	0.75 in	1.50 in	15.5 psi 1.069 bar	0 psig 2000 psig 0 barg 138 barg
5620	DN 25 1 in	1.00 in	2.00 in	4.2 psi 0.290 bar	0 psig 1500 psig 0 barg 103 barg
5621	DN 25 1 in	1.00 in	2.00 in	6.1 psi 0.421 bar	0 psig 1500 psig 0 barg 103 barg
5622	DN 25 1 in	1.00 in	2.00 in	9.4 psi 0.648 bar	0 psig 1500 psig 0 barg 103 barg
Part #	Size	Line Size Inlet (FNPT) A	Outside Thread (MNPT) B	Valve Cracking Pressure	Cold Working Pressure
5623	DN 25 1 in	1.00 in	2.00 in	12.9 psi 0.889 bar	0 psig 1500 psig 0 barg 103 barg
5654C155	DN 25 1 in	1.00 in	2.00 in	15.5 psi 1.069 bar	0 psig 1500 psig 0 barg 103 barg
5654C318	DN 25 1 in	1.00 in	2.00 in	31.8 psi 2.193 bar	0 psig 1500 psig 0 barg 403 barg
5654C407	DN 25 1 in	1.00 in	2.00 in	40.7 psi 2.806 bar	0 psig 1500 psig 0 barg 103 barg
5624	DN 32 1.25 in	1.25 in	2.50 in	1.8 psi 0.124 bar	0 psig 850 psig 0 barg 58.6 barg
5625	DN 32 1.25 in	1.25 in	2.50 in	2.7 psi 0.186 bar	0 psig 850 psig 0 barg 58.6 barg
5626	DN 32 1.25 in	1.25 in	2.50 in	4.3 psi 0.296 bar	0 psig 850 psig 0 barg 58.6 barg
5627	DN 32 1.25 in	1.25 in	2.50 in	6.0 psi 0.414 bar	0 psig 850 psig 0 barg 58.6 barg
5628	DN 32 1.25 in	1.25 in	2.50 in	12.3 psi 0.848 bar	0 psig 850 psig 0 barg 58.6 barg
5655C148	DN 32 1.25 in	1.25 in	2.50 in	14.8 psi 1.02 bar	0 psig 850 psig 0 barg 58.6 barg
5655C188	DN 32 1.25 in	1.25 in	2.50 in	18.8 psi 1.296 bar	0 psig 850 psig 0 barg 58.6 barg
Part #	Size	Line Size Inlet (FNPT) A	Outside Thread (MNPT) B	Valve Cracking Pressure	Cold Working Pressure
5629	DN 40 1.5 in	1.50 in	3.00 in	2.4 psi 0.165 bar	0 psig 700 psig 0 barg 48.3 barg
5630	DN 40 1.5 in	1.50 in	3.00 in	3.8 psi 0.262 bar	0 psig 700 psig 0 barg 48.3 barg
5631	DN 40 1.5 in	1.50 in	3.00 in	7.8 psi 0.538 bar	0 psig 700 psig 0 barg 48.3 barg
5638	DN 40 1.5 in	1.50 in	3.00 in	9.8 psi 0.676 bar	0 psig 700 psig 0 barg 48.3 barg
5656C191	DN 40 1.5 in	1.50 in	3.00 in	19.1 psi 1.317 bar	0 psig 700 psig 0 barg 48.3 barg
5632	DN 50 2 in	2.00 in	4.00 in	1.7 psi 0.117 bar	0 psig 450 psig 0 barg 31.0 barg
5633	DN 50 2 in	2.00 in	4.00 in	3.4 psi 0.234 bar	0 psig 450 psig 0 barg 31.0 barg
5634	DN 50 2 in	2.00 in	4.00 in	4.6 psi 0.317 bar	0 psig 450 psig 0 barg 31.0 barg
5657C094	DN 50 2 in	2.00 in	4.00 in	9.4 psi 0.648 bar	0 psig 450 psig 0 barg 31.0 barg
5658C046	DN 65 2.5 in	2.50 in	4.00 in	4.6 psi 0.317 bar	0 psig 450 psig 0 barg 31.0 barg
5658C108	DN 65 2.5 in	2.50 in	4.00 in	10.8 psi 0.745 bar	0 psig 450 psig 0 barg 31.0 barg

DFT: Check Valves:

Restrictor Threaded In-Line Check Valve

Check Valve Operation:

Restrictor Check Valve

DFT Restrictor Check Valvecommon service installation:

DFT Restrictor Check Valve
common service installation: