UNF Check Valves | McMaster-Carr

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	Thread Type Thread Type	Show

UNF

	Thread Type Thread Type	Hide

	System of Measurement System of Measurement

Inch

	Thread Size Thread Size

	For Use With For Use With

	Body Material Body Material

Stainless Steel

Brass

Steel

	Maximum Pressure Maximum Pressure

125 psi @ 70° F

5,000 psi

	Connection Style Connection Style

	Threaded

	Minimum Opening Pressure Minimum Opening Pressure

2 psi

5 psi

	Valve Type Valve Type

Check

	Dash Size Dash Size

	Mounting Orientation Mounting Orientation

Horizontal

Vertical

Any Position

	Seal Material Seal Material

Rubber

Stainless Steel

	Connection Connection

Inlet

Outlet

	Gender Gender

Female

Male

	Maximum Temperature Maximum Temperature

Less than 200° F

250° to 299° F

	Minimum Temperature Minimum Temperature

-49° to -25° F

25° F or greater

	Check Valve Type Check Valve Type

Ball

Poppet

	Connection Type Connection Type


Pipe	Hose

	Valve Function Valve Function

Backflow Prevention

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

DFARS Specialty Metals
COTS-Exempt

	Shape Shape

	Straight

	Actuation Actuation

Pressure

	Flow Coefficient (Cv) Flow Coefficient (Cv)

0.081

Not Rated

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About Backflow-Prevention Valves

For Use With: Air, Nitrogen, Water
Ball Material: 304 Stainless Steel
Seal Material: See table

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.

303 stainless steel valves are more corrosion resistant than brass 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.

UNF Female Inlet × UNF Female Outlet

Female Inlet × Female Outlet

						Brass Body		303 Stainless Steel Body
Thread Size	Flow Coefficient (Cv)	Max. Pressure	Min. Opening Pressure, psi	Temperature Range, °F	End-to-End Lg.		Each		Each
304 Stainless Steel Seal
10-32	0.081	125 psi @ 70° F	2	35° to 150°	13/16"	0000000	000000	0000000	000000

Backflow-Prevention Inline Hydraulic Valves

Also known as check valves, these open to allow flow in one direction and close when flow stops or reverses.

Valves with a poppet have internal components that can handle any flow rates. The higher the flow rate of the hydraulic fluid coming into the valve, the lower the pressure the fluid is as it leaves the valve.

UN/UNF (SAE) thread connections have straight threads and are also known as O-ring Boss fittings.

UN/UNF (ORFS) threads are also known as O-ring face seal threads.

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

UN/UNF (SAE) Male Inlet × UN/UNF (JIC) Male Outlet—Poppet Check Valve

UN/UNF (SAE) — UN/UNF (JIC)

Inlet Connection		Outlet Connection
Thread Size	Dash Size	Thread Size	Dash Size	Flared Angle	Max. Flow Rate	Flow Coefficient (Cv)	Max. Pressure, psi	Min. Opening Pressure, psi	Seal Material	Port-to-Port Lg.	Hex Wd.	Mounting Orientation	Temp. Range, °F		Each
Steel Body
7/16"-20	04	7/16"-20	04	37°	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 1/4"	9/16"	Any Position	-40° to 250°	0000000	000000
9/16"-18	06	9/16"-18	06	37°	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 1/4"	3/4"	Any Position	-40° to 250°	0000000	00000
3/4"-16	08	3/4"-16	08	37°	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 5/8"	7/8"	Any Position	-40° to 250°	0000000	00000
7/8"-14	10	7/8"-14	10	37°	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 7/8"	1"	Any Position	-40° to 250°	0000000	000000
1 1/16"-12	12	1 1/16"-12	12	37°	Not Rated	Not Rated	5,000	5	Buna-N Rubber	2 1/8"	1 1/4"	Any Position	-40° to 250°	0000000	000000
1 5/16"-12	16	1 5/16"-12	16	37°	Not Rated	Not Rated	5,000	5	Buna-N Rubber	2 1/2"	1 1/2"	Any Position	-40° to 250°	0000000	000000
1 5/8"-12	20	1 5/8"-12	20	37°	Not Rated	Not Rated	5,000	5	Buna-N Rubber	2 5/8"	1 7/8"	Any Position	-40° to 250°	0000000	000000

UN/UNF (SAE) Male Inlet × UN/UNF (ORFS) Male Outlet—Poppet Check Valve

UN/UNF (SAE) — UN/UNF (ORFS)

Inlet Connection		Outlet Connection
Thread Size	Dash Size	Thread Size	Dash Size	Max. Flow Rate	Flow Coefficient (Cv)	Max. Pressure, psi	Min. Opening Pressure, psi	Seal Material	Port-to-Port Lg.	Hex Wd.	Mounting Orientation	Temp. Range, °F		Each
Steel Body
7/16"-20	04	9/16"-18	04	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 1/8"	5/8"	Any Position	-40° to 250°	0000000	000000
9/16"-18	06	11/16"-16	06	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 1/8"	3/4"	Any Position	-40° to 250°	0000000	00000
3/4"-16	08	13/16"-16	08	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 3/8"	7/8"	Any Position	-40° to 250°	0000000	000000
7/8"-14	10	1"-14	10	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 5/8"	1 1/8"	Any Position	-40° to 250°	0000000	000000
1 1/16"-12	12	1 3/16"-12	12	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 7/8"	1 1/4"	Any Position	-40° to 250°	0000000	000000
1 5/16"-12	16	1 7/16"-12	16	Not Rated	Not Rated	5,000	5	Buna-N Rubber	2"	1 1/2"	Any Position	-40° to 250°	0000000	000000

UN/UNF (JIC) Male Inlet × UN/UNF (SAE) Male Outlet—Poppet Check Valve

UN/UNF (JIC) — UN/UNF (SAE)

Inlet Connection			Outlet Connection
Thread Size	Dash Size	Flared Angle	Thread Size	Dash Size	Max. Flow Rate	Flow Coefficient (Cv)	Max. Pressure, psi	Min. Opening Pressure, psi	Seal Material	Port-to-Port Lg.	Hex Wd.	Mounting Orientation	Temp. Range, °F		Each
Steel Body
7/16"-20	04	37°	7/16"-20	04	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 1/4"	9/16"	Any Position	-40° to 250°	0000000	000000
9/16"-18	06	37°	9/16"-18	06	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 1/4"	3/4"	Any Position	-40° to 250°	0000000	00000
3/4"-16	08	37°	3/4"-16	08	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 5/8"	7/8"	Any Position	-40° to 250°	0000000	00000
7/8"-14	10	37°	7/8"-14	10	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 7/8"	1"	Any Position	-40° to 250°	0000000	000000
1 1/16"-12	12	37°	1 1/16"-12	12	Not Rated	Not Rated	5,000	5	Buna-N Rubber	2 1/8"	1 1/4"	Any Position	-40° to 250°	0000000	000000
1 5/16"-12	16	37°	1 5/16"-12	16	Not Rated	Not Rated	5,000	5	Buna-N Rubber	2 1/2"	1 1/2"	Any Position	-40° to 250°	0000000	000000
1 5/8"-12	20	37°	1 5/8"-12	20	Not Rated	Not Rated	5,000	5	Buna-N Rubber	2 5/8"	1 7/8"	Any Position	-40° to 250°	0000000	000000

UN/UNF (ORFS) Male Inlet × UN/UNF (SAE) Male Outlet—Poppet Check Valve

UN/UNF (ORFS) — UN/UNF (SAE)

Inlet Connection		Outlet Connection
Thread Size	Dash Size	Thread Size	Dash Size	Max. Flow Rate	Flow Coefficient (Cv)	Max. Pressure, psi	Min. Opening Pressure, psi	Seal Material	Port-to-Port Lg.	Hex Wd.	Mounting Orientation	Temp. Range, °F		Each
Steel Body
9/16"-18	04	7/16"-20	04	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 1/8"	5/8"	Any Position	-40° to 250°	0000000	000000
11/16"-16	06	9/16"-18	06	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 1/8"	3/4"	Any Position	-40° to 250°	0000000	00000
13/16"-16	08	3/4"-16	08	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 3/8"	7/8"	Any Position	-40° to 250°	0000000	000000
1"-14	10	7/8"-14	10	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 5/8"	1 1/8"	Any Position	-40° to 250°	0000000	000000
1 3/16"-12	12	1 1/16"-12	12	Not Rated	Not Rated	5,000	5	Buna-N Rubber	1 7/8"	1 1/4"	Any Position	-40° to 250°	0000000	000000
1 7/16"-12	16	1 5/16"-12	16	Not Rated	Not Rated	5,000	5	Buna-N Rubber	2"	1 1/2"	Any Position	-40° to 250°	0000000	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	000000	000000
__	50	50	50	Right Hand	9/16"-18	UNF	Left Hand	1/4	NPT	Brass	000000	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	3/8"-24	UNF	Right Hand	3/8"-24	UNF	Brass	000000	000000
125	__	__	__	Right Hand	9/16"-18	UNF	Right Hand	9/16"-18	UNF	Brass	000000	0000
__	50	50	50	Left Hand	3/8"-24	UNF	Left Hand	3/8"-24	UNF	Brass	000000	00000
__	50	50	50	Left Hand	9/16"-18	UNF	Left Hand	9/16"-18	UNF	Brass	000000	0000

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.

Arresters with right-hand threads are for use with oxygen; arresters with left-hand threads are for use with acetylene, hydrogen, and propane.

With Right-Hand Threads

	Male Hose Connection		Female Hose Connection
Max. Pressure for Oxygen, psi	Thread Size	Thread Type	Thread Size	Thread Type	Material	Specifications Met		Each
143	9/16"-18	UNF	9/16"-18	UNF	Brass	European Safety Specification EN730, ISO 5175 Class 1	00000000	000000

With Left-Hand Threads

Max. Pressure, psi			Male Hose Connection		Female Hose Connection
Acetylene	Hydrogen	Propane	Thread Size	Thread Type	Thread Size	Thread Type	Material	Specifications Met		Each
15	50	50	9/16"-18	UNF	9/16"-18	UNF	Brass	European Safety Specification EN730, ISO 5175 Class 1	00000000	000000

With Right-Hand and Left-Hand Threads

Max. Pressure, psi				Male Hose Connection		Female Hose Connection
Oxygen	Acetylene	Hydrogen	Propane	Thread Size	Thread Type	Thread Size	Thread Type	Material	Specifications Met		Pair
143	15	50	50	9/16"-18	UNF	9/16"-18	UNF	Brass	European Safety Specification EN730, ISO 5175 Class 1	00000000	000000

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.