DFT: Check Valves:

Vacuum Breaker Threaded Check Valve

DFT® Vacuum Breakers provide effective protection against collapse of pressure vessels, tanks and rolls.
Vacuum Breakers prevent condensate back-up when equipment is shut down or inlet steam is reduced by modulating control valves.
Vacuum Breakers are used to break siphons, prevent pipe collapse during transient pressure drops, and to provide addition of air on the downstream side of check valves to dampen water hammer.

Documentation:
Product Specifications
(189KB 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.

DFT Vacuum Breaker Threaded In-Line Check Valve

Vacuum Breaker Valve

1” to 4” size
(Outside diameter)
450 to 6000 CWP
Threaded O.D. (MNPT)
Unthreaded inlet bore
Stainless steel construction
Spring-assisted silent closing
Horiz or vert install
Tight shutoff lapped disc & seat

DFT® Vacuum Breakers provide effective protection against collapse of pressure vessels, tanks and rolls. They prevent condensate "back-up" when equipment is shut down or inlet steam is reduced by modulating control valves.

Options:

Inconel® X-750 spring

Soft seat

In piping systems, DFT® Vacuum Breakers are used to break siphons, prevent pipe collapse during transient pressure drops, and to provide addition of air on the downstream side of check valves to dampen water hammer.

Vacuum Breaker			Cracking Pressure
A Nominal Size (MNPT)	B Unthreaded Inlet Bore	Weight	Cv	PSI	Inches of Water
1	0.56	0.38	5.8	0.60	16.7
1-1/2	0.88	0.88	13.2	0.45	12.5
2	1.09	1.25	23.1	0.38	10.5
2-1/2	1.50	2.25	36	0.20	5.5
3	1.72	3.75	57.4	0.14	3.9
4	2.22	7.00	90	0.15	4.3

Cold, Non-Shock Pressure Rating
	1"	1-1/2"	2"	2-1/2"	3"	4"
Vacuum Breaker BSSV	2500	2000	1500	850	700	450
Vacuum Breaker BSSV6	6000	5500	3000	1100	900	450

Sat. Steam Pressure	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 seal and spring materials in chart above.

Materials of Construction
	Vacuum Breaker BSSV	High Pressure Vacuum Breaker BSSV6
Seat	303 SS	316 SS
Disc	316 SS	316 SS
Guard	CF8M	CF8M
Spring	316 SS	316 SS
Retaining Ring	316 SS	316 SS


VACUUM BREAKER THREADED IN-LINE CHECK VALVE
Part #	Size	Nominal Size (MNPT) A	Unthreaded Inlet Bore B	CV	Valve Cracking Pressure	Cold Working Pressure
8033	DN 25 1 in	1.00 in	0.56 in 14 mm	5.8	0.60 psi 0.041 bar 16.7 in.water 424 mm.water 31.1 mmHg	0 - 2500 psig 0 - 172 barg
8103	DN 25 1 in	1.00 in	0.56 in 14 mm	5.8	0.24 psi 0.017 bar 16.7 in.water 424 mm.water 31.1 mmHg	0 - 2500 psig 0 - 172 barg
8034	DN 40 1.5 in	1.50 in	0.88 in 22 mm	13.2	0.44 psi 0.030 bar 12.1 in.water 307 mm.water 22.6 mmHg	0 - 2000 psig 0 - 138 barg
8035	DN 50 2 in	2.00 in	1.09 in 28 mm	23.1	0.36 psi 0.025 bar 10.1 in.water 257 mm.water 18.8 mmHg	0 - 1500 psig 0 - 103 barg
8036	DN 65 2.5 in	2.50 in	1.50 in 38 mm	36	0.16 psi 0.011 bar 4.5 in.water 114 mm.water 8.4 mmHg	0 - 850 psig 0 - 58.6 barg
8037	DN 80 3 in	3.00 in	1.72 in 44 mm	57.4	0.15 psi 0.010 bar 4.2 in.water 107 mm.water 7.8 mmHg	0 - 700 psig 0 - 48.3 barg
8038	DN 100 4 in	4.00 in	2.22 in 56 mm	90	0.10 psi 0.007 bar 2.6 in.water 66 mm.water 4.8 mmHg	0 - 450 psig 0 - 31.0 barg
8094	DN 25 1 in	1.00	0.56 in 14 mm	5.8	0.60 psi 0.041 bar 16.7 in.water 424 mm.water 31.1 mmHg	0 - 6000 psig 0 - 414 barg
8095	DN 40 1.5 in	1.50 in	0.88 in 22 mm	13.2	0.44 psi 0.030 bar 12.1 in.water 307 mm.water 22.6 mmHg	0 - 5500 psig 0 - 379 barg
8096	DN 50 2 in	2.00 in	1.09 in 28 mm	23.1	0.36 psi 0.025 bar 10.1 in.water 257 mm.water 18.8 mmHg	0 - 3000 psig 0 - 207 barg
8097	DN 65 2.5 in	2.50 in	1.50 in 38 mm	36	0.16 psi 0.011 bar 4.5 in.water 114 mm.water 18.4 mmHg	0 - 1100 psig 0 - 75.8 barg
8098	DN 80 3 in	3.00 in	1.72 in 44 mm	57.4	0.15 psi 0.010 bar 4.2 in.water 107 mm.water 7.8 mmHg	0 - 900 psig 0 - 62.1 barg
8099	DN 100 4 in	4.00 in	2.22 in 56 mm	90	0.10 psi 0.007 bar 2.6 in.water 66 mm.water 4.8 mmHg	0 - 450 psig 0 - 31.0 barg

Designed to prevent Water Hammer

The spring-assisted, non-slam design featured in all DFT® check valves insures that as the forward flow in a pipeline decreases, the disc begins moving closer to the seat.

By the time the flow stops, the disc is closed against the seat preventing flow reversal. This prevents the valve from slamming closed which can cause “Water Hammer” and the resultant noise and damage to piping systems.

Liquids, gas or steam

All DFT non-slam check valves provide positive shutoff for applications involving liquids, gas or steam and can be used in most industries including oil and gas, petrochemical, pulp and paper, textiles and more.

Meet or exceed MSS SP-61 leakage requirements

Metal-to-metal seating is standard in all DFT non-slam check valves. Cast iron valves meet AWWA seat leakage requirements.
Available with soft seats for bubble-tight shutoff.

NACE

DFT check valves can meet NACE standards MR0103-2003 and MR0175/ISO 15156.

Custom sizing available

The following DFT check valves can be sized to the appropriate flow conditions: ALC®, Excalibur®, GLC® and WLC®.