DFT: Check Valves:

Basic-Check® Threaded In-Line Check Valve

Versatile all-purpose, spring-assisted, in-line check valve.
The valve consists of a guard cage, spring, valve disc, retaining ring and seat.
Disc and seat is precision lapped, providing very tight shut-off of both gas and liquid.
If bubble-tight shut-off is required, resilient soft seats are available.
low maintenance service for a wide range of liquids and gases at various pressure/temperature combinations.

Documentation:
Product Specifications
(115KB PDF)

Please use the form below to request a quote:

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.

Typically, pressure drop is calculated based on the check valve being 100% open as with on/off valves. However, if the flow is not sufficient to achieve full opening, but instead, the check valve is only partially open, the pressure drop will be greater than calculated since the flow passage is restricted by the disc being in the flow path.

In this situation, a large rated Cv actually becomes detrimental to the check valve (unlike with on/off valves), resulting in fluttering of the disc and eventual failure.

Two of the most common problems with check valves are reverse flow and water hammer. In both situations, a fast-closing valve is desired.

When installing check valves, point the “flow arrow” in the direction of the flow to allow the valve to perform its function. The flow arrow can be found on the body or tag.

DFT Basic-Check Threaded In-Line Check Valve

Basic-Check Valve

1/4” to 2-1/2” Line size
450 to 6000 CWP
Threaded ends
Stainless steel construction
Spring-assisted silent closing
Horizontal or vertical installation

DFT Basic-Check® Valve
used with reducing coupling:

The DFT® Basic-Check Valve is a versatile all-purpose, non-slam valve that provides reliable, low-maintenance service for a wide range of liquids, steam and gases at various pressure/temperature combinations.

The valve consists of a guard cage, spring, valve disc, retaining ring and seat. It can be combined with pipe fittings such as reducing couplings, drain elbows, etc. to form a complete check valve unit ideally suited for a broad range of pipeline applications or incorporated into machinery for OEM applications.

The metal-to-metal sealing area of the Basic-Check valve’s disc and seat is precision-lapped, providing very tight shutoff of gas, steam and liquid. If bubble-tight shutoff is required, optional resilient soft seats are available.

Basic-Check Cracking Pressure
A Line Size Inlet (FNPT)	B Outside Thread (MNPT)	Weight	Cv	PSI	Inches of Water
1/4	1	0.38	5.8	0.60 (1)	16.7
3/8	1	0.38	5.8	0.60 (1)	16.7
1/2	1	0.38	5.8	0.60 (1)	16.7
3/4	1-1/2	0.88	13.2	0.45	12.5
1	2	1.25	23.1	0.38	10.5
1-1/4	2-1/2	2.25	36	0.20	5.5
1-1/2	3	3.75	57.4	0.14	3.9
2	4	7	90	0.15	4.3
2-1/2	4	7	90	0.15	4.3
*Cracking pressure shown for horizontal installation.

Materials of Construction
Component	Basic-Check BSS	Basic-Check BSA	Basic-Check BSE	High Pressure Basic-Check BSSH6	High Pressure Basic-Check BSSH7
Seat	303 SS	416 SS	303 SS	316 SS	316 SS
Disc	316 SS	316 SS	316 SS	316 SS	17-7 SS
Guard	CF8M (4)	CF8M	17-4 SS	CF8M	CF8M
Spring	316 SS	316 SS	Inconel® X-750	316 SS	316 SS
Retaining Ring	316 SS	316 SS	316 SS	316 SS	316 SS
Notes: 1. Light spring available: Cracking Pressure = .24 PSI (6.5 inches of water) 2. Contingent on service ratings of matching pipe and fittings. 3. Saturated steam pressure is given for reference only; pressure limit of valve is the adjusted rating at the given temperature. 4. 1/4”, 3/8” and 1/2” BSS units have a 303 SS guard.

Basic-Check: Cold, Non-shock Pressure Rating (PSIG)
Valve	1/4", 3/8", 1/2"	3/4"	1"	1-1/4"	1-1/2"	2"	2-1/2"
Basic-Check BSS, BSA, BSE	2500	2000	1500	850	700	450	450
High-Pressure BSSH6	6000	5500	3000	1100	900	450	450
High-Pressure BSSH7	6000	6000	6000	4000	2700	800	800

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.

BASIC CHECK VALVES
Part #	Size	Line Size Inlet (FNPT) A	Style	Outside Thread (MNPT) B	Cv	Valve Cracking Pressure	Cold Working Pressure
8001	DN 8 0.25 in	0.25 in	BSS	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 2500 psig 0 barg 172 barg
8028	DN 8 0.25 in	0.25 in	BSE	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 2500 psig 0 barg 172 barg
8057	DN 8 0.25 in	0.25 in	BSSH6	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 6000 psig 0 barg 414 barg
8020	DN 8 0.25 in	0.25 in	BSSH7	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 6000 psig 0 barg 414 barg
8012	DN 8 0.25 in	0.25 in	BS316S	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 2500 psig 0 barg 172 barg
8029	DN 10 0.38 in	0.38 in	BSE	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 2500 psig 0 barg 172 barg
8002	DN 10 0.38 in	0.38 in	BSS	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 2500 psig 0 barg 172 barg
8058	DN 10 0.38 in	0.38 in	BSSH6	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 6000 psig 0 barg 414 barg
8021	DN 10 0.38 in	0.38 in	BSSH7	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 2500 psig 0 barg 172 barg
8013	DN 10 0.38 in	0.38 in	BS316S	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 2500 psig 0 barg 172 barg
8030	DN 15 0.5 in	0.5 in	BSE	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 2500 psig 0 barg 172 barg
Part #	Size	Line Size Inlet (FNPT) A	Style	Outside Thread (MNPT) B	Cv	Valve Cracking Pressure	Cold Working Pressure
8003	DN 15 0.5 in	0.50 in	BSS	1.00 in	5.8	0.60 psig 0.041 bar 16.7 in water 424 mm water 31.1 mm Hg	0 psig 2500 psig 0 barg 172 barg
8066	DN 15 0.5 in	0.5 in	BSS	1.00 in	5.8	0.24 psig 0.017 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 2500 psig 0 barg 172 barg
8059	DN 15 0.5 in	0.5 in	BSSH6	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 6000 psig 0 barg 414 barg
8022	DN 15 0.5 in	0.5 in	BSSH7	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 6000 psig 0 barg 414 barg
8014	DN 15 0.5 in	0.5 in	BS316S	1.00 in	5.8	0.60 psi 0.041 bar 16.7 in. water 424 mm. water 31.1 mmHg	0 psig 2500 psig 0 barg 172 barg
8031	DN 20 0.75 in	0.75 in	BSE	1.50 in	13.2	0.44 psi 0.030 bar 12.1 in water 307 mm water 22.6 mm Hg	0 psig 2000 psig 0 barg 138 barg
8004	DN 20 0.75 in	0.75 in	BSS	1.50 in	13.2	0.44 psig 0.030 bar 12.1 in water 307 mm water 22.6 mm Hg	0 psig 2000 psig 0 barg 138 barg
8060	DN 20 0.75 in	0.75 in	BSSH6	1.50 in	13.2	0.44 psig 0.030 bar 12.1 in water 307 mm water 22.6 mm Hg	0 psig 5500 psig 0 barg 379 barg
8023	DN 20 0.75 in	0.75 in	BSSH7	1.50 in	13.2	0.44 psig 0.030 bar 12.1 in water 307 mm water 22.6 mm Hg	0 psig 6000 psig 0 barg 138 barg
8015	DN 20 0.75 in	0.75 in	BS316S	1.50 in	13.2	0.44 psig 0.030 bar 12.1 in water 307 mm water 22.6 mm Hg	0 psig 2000 psig 0 barg 138 barg
8032	DN 25 1 in	1.00 in	BSE	2.00 in	23.1	0.36 psig 0.025 bar 10.1 in water 257 mm water 18.8 mm Hg	0 psig 1500 psig 0 barg 103 barg
Part #	Size	Line Size Inlet (FNPT) A	Style	Outside Thread (MNPT) B	Cv	Valve Cracking Pressure	Cold Working Pressure
8005	DN 25 1 in	1.00 in	BSS	2.00 in	23.1	0.36 psig 0.025 bar 10.1 in water 257 mm water 18.8 mm Hg	0 psig 1500 psig 0 barg 103 barg
8061	DN 25 1 in	1.00 in	BSSH6	2.00 in	23.1	0.36 psig 0.025 bar 10.1 in water 257 mm water 18.8 mm Hg	0 psig 3000 psig 0 barg 207 barg
8024	DN 25 1 in	1.00 in	BSSH7	2.00 in	23.1	0.36 psig 0.025 bar 10.1 in water 257 mm water 18.8 mm Hg	0 psig 6000 psig 0 barg 414 barg
8016	DN 25 1 in	1.00 in	BS316S	2.00 in	23.1	0.36 psig 0.025 bar 10.1 in water 257 mm water 18.8 mm Hg	0 psig 1500 psig 0 barg 103 barg
8009	DN 32 1.25 in	1.25 in	BSA	2.50 in	36.0	0.16 psig 0.011 bar 4.5 in water 114 mm water 8.4 mm Hg	0 psig 850 psig 0 barg 58.6 barg
8006	DN 32 1.25 in	1.25 in	BSS	2.50 in	36	0.26 psig 0.011 bar 4.5 in water 114 mm water 8.4 mm Hg	0 psig 850 psig 0 barg 58.6 barg
8062	DN 32 1.25 in	1.25 in	BSSH6	2.50 in	36.0	0.16 psig 0.011 bar 4.5 in water 114 mm water 8.4 mm Hg	0 psig 1100 psig 0 barg 75.8 barg
8025	DN 32 1.25 in	1.25 in	BSSH7	2.50 in	36	0.26 psig 0.011 bar 4.5 in water 114 mm water 8.4 mm Hg	0 psig 4000 psig 0 barg 276 barg
8017	DN 32 1.25 in	1.25 in	BS316S	2.50 in	36.0	0.16 psig 0.011 bar 4.5 in water 114 mm water 8.4 mm Hg	0 psig 850 psig 0 barg 58.6 barg
8007	DN 40 1.5 in	1.50 in	BSS	3.00 in	57.4	0.15 psig 0.010 bar 4.2 in water 107 mm water 7.8 mm Hg	0 psig 700 psig 0 barg 48.3 barg
8063	DN 40 1.5 in	1.50 in	BSSH6	3.00 in	57.4	0.15 psig 0.010 bar 4.2 in water 107 mm water 7.8 mm Hg	0 psig 900 psig 0 barg 62.1 barg
Part #	Size	Line Size Inlet (FNPT) A	Style	Outside Thread (MNPT) B	Cv	Valve Cracking Pressure	Cold Working Pressure
8026	DN 40 1.5 in	1.50 in	BSSH7	3.00 in	57.4	0.15 psig 0.010 bar 4.2 in water 107 mm water 7.8 mm Hg	0 psig 2700 psig 0 barg 186 barg
8018	DN 40 1.5 in	1.50 in	BS316S	3.00 in	57.4	0.15 psig 0.010 bar 4.2 in water 107 mm water 7.8 mm Hg	0 psig 700 psig 0 barg 48.3 barg
8010	DN 40 1.5 in	1.50 in	BSA	3.00 in	57.4	0.15 psig 0.010 bar 4.2 in water 107 mm water 7.8 mm Hg	0 psig 700 psig 0 barg 48.3 barg
8011	DN 50 2 in	2.00 in	BSA	4.00 in	90	0.10 psig 0.007 bar 2.6 in water 66 mm water 4.8 mm Hg	0.10 psig 450 psig 0 barg 31.0 barg
8008	DN 50 2 in	2.00 in	BSS	4.00 in	90	0.10 psig 0.007 bar 2.6 in water 66 mm water 4.8 mm Hg	0 psig 450 psig 0 barg 31 barg
8064	DN 50 2 in	2.00 in	BSSH6	4.00 in	90	0.10 psig 0.007 bar 2.6 in water 66 mm water 4.8 mm Hg	0.10 psig 450 psig 0 barg 31.0 barg
8027	DN 50 2 in	2.00 in	BSSH7	4.00 in	90	0.10 psig 0.007 bar 2.6 in water 66 mm water 4.8 mm Hg	0 psig 800 psig 0 barg 55.2 barg
8019	DN 50 2 in	2.00 in	BS316S	4.00 in	90	0.10 psig 0.007 bar 2.6 in water 66 mm water 4.8 mm Hg	0 psig 450 psig 0 barg 31.0 barg
8000	DN 65 2.5 in	2.50 in	BSS	4.00 in	90	0.10 psig 0.007 bar 2.6 in water 66 mm water 4.8 mm Hg	0 psig 450 psig 0 barg 31.0 barg
8065	DN 65 2.5 in	2.50 in	BSSH6	4.00 in	90	0.10 psig 0.007 bar 2.6 in water 66 mm water 4.8 mm Hg	0 psig 450 psig 0 barg 31.0 barg
8090	DN 65 2.5 in	2.50 in	BSSH7	4.00 in	90	0.10 psig 0.007 bar 2.6 in water 66 mm water 4.8 mm Hg	0 psig 800 psig 0 barg 55.2 barg

DFT: Check Valves:

Basic-Check® Threaded In-Line Check Valve

Check Valve Operation:

Basic-Check Valve

DFT Basic-Check® Valveused with reducing coupling:

DFT Basic-Check® Valve
used with reducing coupling: