UNF Check Valves | McMaster-Carr

Filter by

System of Measurement

Inch

Minimum Opening Pressure

Thread Size

Thread Type

UN/UNF (SAE Straight)

For Use With

Body Material

Maximum Pressure

Fitting Connection

Connects To

Pipe Size

Actuation

Flow Coefficient (Cv)

Shape

Material

Inlet Thread Type

Fitting Type

Outlet Gender

Gender

Check Valve Type

U.S.–Mexico–Canada Agreement (USMCA) Qualifying

REACH

RoHS

Compliant with Exemptions

Not Compliant

DFARS Specialty Metals

Exempt

Export Control Classification Number (ECCN)

2B999

EAR99

Maximum Pressure @ Temperature

End-to-End Length

30 Products

Air Flow Check Valves

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

UNF Female Inlet × UNF Female Outlet

Flow Coefficient (Cv)—Flow coefficient (Cv) is a measurement that indicates how much airflow can pass through a valve.

									Overall
	Inlet Thread Size	Outlet Thread Size	Flow Coefficient (Cv)	Min. Flow Rate	Max. Flow Rate, scfm	Max. Pressure, psi	Min. Opening Pressure, psi	Temp. Range, ° F	Lg.	Dia.		Each
Brass Body



		10-32	10-32	0.09	Not Rated	9.5	125	0.1	-20 to 160	13/16"	5/16"	1096T11	00000

Compact Threaded Check Valves

With a shorter end-to-end length than other check valves, these fit in tight spaces. They open to allow flow in one direction and close when flow stops or reverses.

UNF Female Inlet × UNF Female Outlet

Female Inlet ×

Female Outlet

303 Stainless Steel Body—303 stainless steel valves are more corrosion resistant than brass valves.

Flow Coefficient (Cv)—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.

									Brass Body		303 Stainless Steel Body
	Thread Size	Flow Coefficient (Cv)	Max. Pressure @ Temp.	Min. Opening Pressure, psi	Temp. Range, ° F	End-to-End Lg.	For Use With	Ball Material		Each		Each
304 Stainless Steel Seal



		10-32	0.081	125 psi @ 70° F	2	35 to 150	13/16"	Air, Nitrogen, Water	304 Stainless Steel	8567T31	000000	8567T32	000000

Welding Gas Check Valves for Regulators

Stop the reverse flow of gas in your regulator. Check valves do not stop flashbacks.

Max. Pressure, psi				Male Hose Connection			Male Pipe Connection
Oxygen	Acetylene	Hydrogen	Propane	Thread Direction	Thread Size	Thread Type	Thread Direction	Pipe Size	Thread Type	Material		Each
125	—	—	—	Right Hand	9/16"-18	UNF	Right Hand	1/4	NPT	Brass	7957A3	000000
—	50	50	50	Right Hand	9/16"-18	UNF	Left Hand	1/4	NPT	Brass	7957A4	00000

Welding Gas Check Valves for Torches

Stop the reverse flow of gas in your torch. Check valves do not stop flashbacks.

Max. Pressure, psi				Male Hose Connection			Female Hose Connection
Oxygen	Acetylene	Hydrogen	Propane	Thread Direction	Thread Size	Thread Type	Thread Direction	Thread Size	Thread Type	Material		Each
125	—	—	—	Right Hand	9/16"-18	UNF	Right Hand	9/16"-18	UNF	Brass	7957A1	000000
—	50	50	50	Left Hand	3/8"-24	UNF	Left Hand	3/8"-24	UNF	Brass	7957A8	00000
—	50	50	50	Left Hand	9/16"-18	UNF	Left Hand	9/16"-18	UNF	Brass	7957A2	00000

Welding Gas Flashback Arresters for Regulators

Attach these arresters to the outlet connection of a regulator on a torch that cuts steel up to 11" thick. Arresters extinguish flames and have a check valve to stop reverse gas flow. They are reusable; resetting is not required after flashback.

Right-Hand Threads—UNF Male × UNF Female

Standard

Flashback

Arresters

High Flow

Flashback

Arresters

Quick Disconnect

Flashback Arresters

Arresters with right-hand threads are for use with oxygen.

High Flow Flashback Arresters—High-flow arresters give you twice the airflow rate compared to standard flashback arresters when they’re used at the same inlet pressure. They are often used with larger torch tips.

Quick Disconnect Flashback Arresters—Quick-disconnect arresters have a fitting that connects and disconnects them from your torch, so you don't have to thread these arresters on and off with a wrench.

	Max. Pressure for Oxygen, psi	Material	Specs. Met		Each
Standard Flashback Arresters



	3/8"-24	143	Brass	EN 730, ISO 5175	7942A51	000000


	9/16"-18	143	Brass	EN 730, ISO 5175	78335A67	00000


	High Flow Flashback Arresters



			9/16"-18	143	Brass	EN 730, ISO 5175	78335A36	000000


			7/8"-14	143	Brass	EN 730, ISO 5175	78335A52	000000


			Quick Disconnect Flashback Arresters



					9/16"-18	143	Brass	EN 561, ISO 7289	78335A56	000000

Left-Hand Threads—UNF Male × UNF Female


Standard Flashback Arresters	High Flow Flashback Arresters	Quick Disconnect Flashback Arresters

Arresters with left-hand threads are for use with acetylene, hydrogen, and propane.

		Max. Pressure, psi
	Thread Size	Acetylene	Hydrogen	Propane	Material	Specs. Met		Each
Standard Flashback Arresters



		3/8"-24	15	50	50	Brass	EN 730, ISO 5175	7942A52	000000


		9/16"-18	15	50	50	Brass	EN 730, ISO 5175	78335A25	00000


		High Flow Flashback Arresters



				9/16"-18	15	50	50	Brass	EN 730, ISO 5175	78335A28	000000


				7/8"-14	15	50	50	Brass	EN 730, ISO 5175	78335A51	000000


				Quick Disconnect Flashback Arresters



						9/16"-18	15	50	50	Brass	EN 561, ISO 7289	78335A55	000000

Right-Hand and Left-Hand Threads—UNF Male × UNF Female

Standard

Flashback

Arresters

Arresters with right-hand threads are for use with oxygen.

Arresters with left-hand threads are for use with acetylene, hydrogen, and propane.

		Max. Pressure, psi
	Thread Size	Oxygen	Acetylene	Hydrogen	Propane	Material	Specs. Met		Pair
Standard Flashback Arresters



		9/16"-18	143	15	50	50	Brass	EN 730, ISO 5175	78335A43	0000000

Welding Gas Flashback Arresters for Torches

These arresters attach directly to torches that cut steel up to 8" thick. They extinguish flames and have a check valve to stop reverse gas flow. They are reusable; resetting is not required after flashback.

Right-Hand Threads—UNF Male × UNF Female

Standard

Flashback

Arresters

High Flow

Flashback

Arresters

Quick Disconnect

Flashback Arresters

Arresters with right-hand threads are for use with oxygen.

	Max. Pressure for Oxygen, psi	Material	Specs. Met		Each
Standard Flashback Arresters



	9/16"-18	143	Brass	EN 730, ISO 5175	78335A31	000000


	High Flow Flashback Arresters



			3/8"-24	143	Brass	EN 730, ISO 5175	7942A11	00000


			9/16"-18	143	Brass	EN 730, ISO 5175	78335A47	000000
			7/8"-14	143	Brass	EN 730, ISO 5175	78335A49	000000


			Quick Disconnect Flashback Arresters



					9/16"-18	143	Brass	EN 561, ISO 7289	78335A65	00000

Left-Hand Threads—UNF Male × UNF Female


Standard Flashback Arresters	High Flow Flashback Arresters	Quick Disconnect Flashback Arresters

Arresters with left-hand threads are for use with acetylene, hydrogen, and propane.

		Max. Pressure, psi
	Thread Size	Acetylene	Hydrogen	Propane	Material	Specs. Met		Each
Standard Flashback Arresters



		9/16"-18	15	50	50	Brass	EN 730, ISO 5175	78335A22	000000


		High Flow Flashback Arresters



				3/8"-24	15	50	50	Brass	EN 730, ISO 5175	7942A12	00000


				9/16"-18	15	50	50	Brass	EN 730, ISO 5175	78335A46	000000
				7/8"-14	15	50	50	Brass	EN 730, ISO 5175	78335A48	000000


				Quick Disconnect Flashback Arresters



						9/16"-18	15	50	72	Brass	EN 561, ISO 7289	78335A24	00000

Right-Hand and Left-Hand Threads—UNF Male × UNF Female

Standard

Flashback

Arresters

Arresters with right-hand threads are for use with oxygen.

Arresters with left-hand threads are for use with acetylene, hydrogen, and propane.

		Max. Pressure, psi
	Thread Size	Oxygen	Acetylene	Hydrogen	Propane	Material	Specs. Met		Pair
Standard Flashback Arresters



		9/16"-18	143	15	50	50	Brass	EN 730, ISO 5175	78335A41	0000000