Union Check Valves | McMaster-Carr

	Pipe Size Pipe Size

1/4
3/8
1/2
3/4
1
1 1/4
1 1/2
2
3
4

	Thread Type Thread Type

NPT

BSPP

	Body Material Body Material

Plastic

Stainless Steel

Brass

	For Use With For Use With

	Connection Style Connection Style


Threaded	Threaded Union

	Mounting Orientation Mounting Orientation

Horizontal

Vertical

	Valve Type Valve Type

Check

Dual Check

	Check Valve Type Check Valve Type

Ball

Spring-Loaded Piston

	Color Color

	Dark Gray
	Light Gray
	White

	Ball Material Ball Material

PVC Plastic

CPVC Plastic

Polypropylene Plastic

	Maximum Pressure Maximum Pressure

150 psi @ 70° F

1,500 psi @ 70° F

175 psi @ 180° F

	Gender Gender

Female

Male

	Maximum Temperature Maximum Temperature

	Minimum Temperature Minimum Temperature

-10° F

35° F

40° F

	Minimum Opening Pressure Minimum Opening Pressure

	Specifications Met Specifications Met

ASTM

NSF/ANSI

	End-to-End Length End-to-End Length

	Fitting Type Fitting Type

Connector

Adapter

	Connection Connection

Inlet

Outlet

	Flow Coefficient (Cv) Flow Coefficient (Cv)

	DFARS (Defense Acquisition Regulations Supplement) DFARS (Defense Acquisition Regulations Supplement)

DFARS Specialty Metals
COTS-Exempt

	Seal Material Seal Material

Fluoroelastomer Rubber

EPDM Rubber

	Fitting Style Fitting Style

Double Union

Single Union

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44 Products

About Backflow-Prevention Valves

Assembled View

Exploded View

To reduce installation time and allow for maintenance without detaching pipe connections, these valves have union fittings. The plastic body and fluoroelastomer seal provide excellent chemical resistance. Valves open to allow flow in one direction and close when flow stops or reverses.

Valves for drinking water meet NSF/ANSI 61.

PVC and CPVC valves come with unthreaded socket-connect female fittings in addition to the threaded NPT female fittings.

Polypropylene valves are more corrosion resistant than PVC or CPVC valves.

Flow coefficient (Cv) is the amount of water (in gallons per minute) at 60° F that will flow through a fully open valve with a difference of 1 psi between the inlet and the outlet.

For technical drawings and 3-D models, click on a part number.

PVC Plastic Body

For Use With:
BSPP thread type:
Butane, Kerosene, Drinking Water, Liquid Carbon Dioxide, Natural Gas, Nitric Acid, Oxygen, Phosphoric Acid, Propane, Salt Water, Soap Solutions, Water
NPT thread type:
Citric Acid, Diesel Fuel, Drinking Water, Ethylene Glycol, Hydrochloric Acid, Isopropyl Alcohol, Kerosene, Nitric Acid, Oil, Phosphoric Acid, Salt Water, Sodium Hypochlorite, Water
Ball Material: PVC Plastic
Seal Material: Fluoroelastomer Rubber

BSPP Female × BSPP Female
Pipe Size	Flow Coefficient (Cv)	Max. Pressure	Min. Opening Pressure, psi	Temperature Range, °F	Color	End-to-End Lg.	Specifications Met		Each
1/2	6.3	150 psi @ 70° F	1	40° to 140°	Dark Gray	4 1/4"	ASTM D1784, NSF/ANSI 61	0000000	000000
1	25	150 psi @ 70° F	1	40° to 140°	Dark Gray	5 3/16"	ASTM D1784, NSF/ANSI 61	0000000	000000
NPT Female × NPT Female
1/2	4.8	150 psi @ 70° F	1	40° to 140°	Dark Gray	4 11/16"	ASTM D1784, NSF/ANSI 61	0000000	00000
3/4	7.7	150 psi @ 70° F	1	40° to 140°	Dark Gray	4 3/4"	ASTM D1784, NSF/ANSI 61	0000000	00000
1	11	150 psi @ 70° F	1	40° to 140°	Dark Gray	5 3/8"	ASTM D1784, NSF/ANSI 61	0000000	00000
1 1/4	25	150 psi @ 70° F	1	40° to 140°	Dark Gray	6 1/4"	ASTM D1784, NSF/ANSI 61	0000000	00000
1 1/2	45	150 psi @ 70° F	1	40° to 140°	Dark Gray	6 3/4"	ASTM D1784, NSF/ANSI 61	0000000	00000
2	130	150 psi @ 70° F	1	40° to 140°	Dark Gray	8 1/8"	ASTM D1784, NSF/ANSI 61	0000000	000000

CPVC Plastic Body

For Use With: Citric Acid, Diesel Fuel, Drinking Water, Hydrochloric Acid, Isopropyl Alcohol, Kerosene, Nitric Acid, Phosphoric Acid, Salt Water, Sodium Hypochlorite, Water
Ball Material: CPVC Plastic
Seal Material: Fluoroelastomer Rubber

NPT Female × NPT Female
Pipe Size	Flow Coefficient (Cv)	Max. Pressure	Min. Opening Pressure, psi	Temperature Range, °F	Color	End-to-End Lg.	Specifications Met		Each
1/2	4.8	150 psi @ 70° F	1	35° to 190°	Light Gray	4 11/16"	ASTM D1784, NSF/ANSI 61	0000000	000000
3/4	7.7	150 psi @ 70° F	1	35° to 190°	Light Gray	4 3/4"	ASTM D1784, NSF/ANSI 61	0000000	00000
1	11	150 psi @ 70° F	1	35° to 190°	Light Gray	5 3/8"	ASTM D1784, NSF/ANSI 61	0000000	00000
1 1/4	25	150 psi @ 70° F	1	35° to 190°	Light Gray	6 1/4"	ASTM D1784, NSF/ANSI 61	0000000	000000
1 1/2	45	150 psi @ 70° F	1	35° to 190°	Light Gray	6 3/4"	ASTM D1784, NSF/ANSI 61	0000000	000000
2	130	150 psi @ 70° F	1	35° to 190°	Light Gray	8 1/8"	ASTM D1784, NSF/ANSI 61	0000000	000000

Polypropylene Plastic Body

For Use With: Citric Acid, Hydrochloric Acid, Isopropyl Alcohol, Kerosene, Nitric Acid, Phosphoric Acid, Salt Water, Sodium Hypochlorite, Water
Ball Material: Polypropylene Plastic
Seal Material: Fluoroelastomer Rubber

NPT Female × NPT Female
Pipe Size	Flow Coefficient (Cv)	Max. Pressure	Min. Opening Pressure, psi	Temperature Range, °F	Color	End-to-End Lg.	Specifications Met		Each
1/2	4.8	150 psi @ 70° F	1	35° to 160°	White	4 11/16"	ASTM D4101	0000000	000000
3/4	7.7	150 psi @ 70° F	1	35° to 160°	White	4 3/4"	ASTM D4101	0000000	000000
1	11	150 psi @ 70° F	1	35° to 160°	White	5 3/8"	ASTM D4101	0000000	000000
1 1/2	45	150 psi @ 70° F	1	35° to 160°	White	6 3/4"	ASTM D4101	0000000	000000
2	130	150 psi @ 70° F	1	35° to 160°	White	8 1/8"	ASTM D4101	0000000	000000

Threaded Check Valves for Harsh Chemicals

These valves open to allow flow in one direction and close when flow stops or reverses.

Valves for drinking water meet NSF/ANSI Standard 61.

Polypropylene valves are more corrosion resistant than PVC or CPVC valves.

Flow coefficient (Cv) is the amount of water (in gallons per minute) at 60° F that will flow through a fully open valve with a difference of 1 psi between the inlet and the outlet.

For technical drawings and 3-D models, click on a part number.

PVC Plastic Body—Ball

For Use With: Air, Butane, Carbon Dioxide, Citric Acid, Deionized Water, Diesel Fuel, Drinking Water, Ethanol, Ethylene Glycol, Hydrochloric Acid, Isopropyl Alcohol, Kerosene, Methanol, Mineral Spirits, Natural Gas, Oil, Oxygen, Phosphoric Acid, Potable Water, Propane, Salt Water, Soap Solutions, Sodium Hydroxide, Sodium Hypochlorite, Water
Ball Material: PVC Plastic
Seal Material: Fluoroelastomer Rubber

NPT Female × NPT Female
Pipe Size	Flow Coefficient (Cv)	Max. Pressure	Min. Opening Pressure, psi	Temperature Range, °F	Color	End-to-End Lg.	Specifications Met		Each
1/4	1	150 psi @ 70° F	1.5	35° to 140°	Dark Gray	3"	ASTM D1784, NSF/ANSI 61	0000000	000000
3/8	3	150 psi @ 70° F	1.5	35° to 140°	Dark Gray	3"	ASTM D1784, NSF/ANSI 61	0000000	00000
3	250	150 psi @ 70° F	1.5	35° to 140°	Dark Gray	10 9/16"	ASTM D1784, NSF/ANSI 61	0000000	000000
4	400	150 psi @ 70° F	1.5	35° to 140°	Dark Gray	12 15/16"	ASTM D1784, NSF/ANSI 61	0000000	000000

CPVC Plastic Body—Ball

For Use With: Air, Butane, Carbon Dioxide, Citric Acid, Deionized Water, Diesel Fuel, Drinking Water, Hydrochloric Acid, Isopropyl Alcohol, Kerosene, Mineral Spirits, Natural Gas, Nitric Acid, Oxygen, Phosphoric Acid, Potable Water, Propane, Salt Water, Soap Solutions, Sodium Hydroxide, Sodium Hypochlorite, Sulfuric Acid, Water
Ball Material: CPVC Plastic
Seal Material: Fluoroelastomer Rubber

NPT Female × NPT Female
Pipe Size	Flow Coefficient (Cv)	Max. Pressure	Min. Opening Pressure, psi	Temperature Range, °F	Color	End-to-End Lg.	Specifications Met		Each
3	250	150 psi @ 70° F	1.5	35° to 190°	Dark Gray	10 9/16"	ASTM D1784, NSF/ANSI 61	0000000	0000000
4	400	150 psi @ 70° F	1.5	35° to 190°	Dark Gray	12 15/16"	ASTM D1784, NSF/ANSI 61	0000000	000000

Polypropylene Plastic Body—Ball

For Use With: Air, Ammonia, Butane, Carbon Dioxide, Citric Acid, Deionized Water, Drinking Water, Ethanol, Ethylene Glycol, Isopropyl Alcohol, Kerosene, Methanol, Natural Gas, Oil, Oxygen, Phosphoric Acid, Potable Water, Salt Water, Soap Solutions, Sodium Hydroxide, Water
Ball Material: Polypropylene Plastic
Seal Material: Fluoroelastomer Rubber

NPT Female × NPT Female
Pipe Size	Flow Coefficient (Cv)	Max. Pressure	Min. Opening Pressure, psi	Temperature Range, °F	Color	End-to-End Lg.	Specifications Met		Each
1/2	4.8	150 psi @ 70° F	1.5	35° to 200°	White	4 5/8"	ASTM D4101, NSF/ANSI 61	0000000	000000
3/4	7.7	150 psi @ 70° F	1.5	35° to 200°	White	4 3/4"	ASTM D4101, NSF/ANSI 61	0000000	000000
1	11	150 psi @ 70° F	1.5	35° to 200°	White	5 1/4"	ASTM D4101, NSF/ANSI 61	0000000	000000
1 1/2	45	150 psi @ 70° F	1.5	35° to 200°	White	6 3/4"	ASTM D4101, NSF/ANSI 61	0000000	000000
2	130	150 psi @ 70° F	1.5	35° to 200°	White	8"	ASTM D4101, NSF/ANSI 61	0000000	000000

Union-Insert Check Valves

Shown with Union Fitting (Sold Separately)

For Use With: Air, Argon, Helium, Krypton, Neon, Water, Xenon
Piston Material: 316 Stainless Steel
Spring Material: 316 Stainless Steel
Seal Material: Fluoroelastomer Rubber

To reduce installation time and allow for maintenance without detaching pipe connections, these valves insert into a union fitting. Union fittings are sold separately. Valves open to allow flow in one direction and close when flow stops or reverses. Body is 316 stainless steel for excellent corrosion resistance.

Flow coefficient (Cv) is the amount of water (in gallons per minute) at 60° F that will flow through a fully open valve with a difference of 1 psi between the inlet and the outlet.

For technical drawings and 3-D models, click on a part number.

Valves								Union Fittings
Pipe Size	Flow Coefficient (Cv)	Max. Pressure	Min. Opening Pressure, psi	Temperature Range, °F	End-to-End Lg.		Each		Each
316 Stainless Steel Body
NPT Female × NPT Female
1/2	2.3	1,500 psi @ 70° F	0.5	-10° to 400°	13/16"	0000000	000000	0000000	0000000
1	6.1	1,500 psi @ 70° F	0.5	-10° to 400°	1 1/16"	0000000	000000	0000000	000000
1 1/2	19	1,500 psi @ 70° F	0.5	-10° to 400°	1 5/16"	0000000	000000	0000000	000000
2	33.3	1,500 psi @ 70° F	0.5	-10° to 400°	1 9/16"	0000000	000000	0000000	000000

Threaded Two-Stage Backflow-Prevention Valves for Drinking Water

Single Union Female Inlet × Female Outlet

Single Union Male Inlet × Female Outlet

Double Union

For Use With: Drinking Water
Seal Material: EPDM Rubber

Keep backflow from contaminating your drinking water supply—these valves meet NSF/ANSI 61 for use with drinking water. They consist of a primary check valve and a secondary check valve. If the primary check fails to close when flow stops or reverses, the secondary check valve engages to prevent backflow.

Single-union valves have a union fitting on one end.

Double-union valves have a union fitting on both ends.

For technical drawings and 3-D models, click on a part number.

Brass Body—Single Union
Pipe Size	Max. Pressure	Min. Opening Pressure, psi	Temperature Range, °F	End-to-End Lg.		Each
NPT Female Inlet × NPT Female Outlet
3/4	175 psi @ 180° F	5	35° to 180°	3 3/4"	00000000	000000
1	175 psi @ 180° F	5	35° to 180°	3 3/4"	00000000	000000
NPT Male Inlet × NPT Female Outlet
3/4	175 psi @ 180° F	5	35° to 180°	3 3/4"	00000000	00000
Brass Body—Double Union
NPT Female Inlet × NPT Female Outlet
1/2	175 psi @ 180° F	5	35° to 180°	3 3/4"	0000000	000000
3/4	175 psi @ 180° F	5	35° to 180°	3 3/4"	0000000	000000
1	175 psi @ 180° F	5	35° to 180°	4"	0000000	000000

About Backflow-Prevention Valves

Easy-to-Install Threaded Check Valves for Harsh Chemicals

Threaded Check Valves for Harsh Chemicals

Union-Insert Check Valves

Threaded Two-Stage Backflow-Prevention Valves for Drinking Water