Brass Vent Caps | McMaster-Carr

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	Body Material Body Material

Iron

Brass

	Screen Material Screen Material

Brass

	For Use With For Use With

	Pipe Size Pipe Size

	Thread Type Thread Type

NPT

UNF

	Thread Size Thread Size

10-32

	Connection Style Connection Style

	Threaded

	Inlet Pipe Size Inlet Pipe Size

	Gender Gender


Female	Male

	Maximum Pressure Maximum Pressure

Less than 100 psi

100 to 249 psi

Not Rated

	Maximum Temperature Maximum Temperature

	System of Measurement System of Measurement

Inch

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

DFARS Specialty Metals
COTS-Exempt

	Inlet Gender Inlet Gender

Female

Male

	Activation Activation

Pressure Driven

Manual

	Fitting Material Fitting Material

Iron

Brass

	Height Height

	Inlet Location Inlet Location

Bottom

	Relief Port Location Relief Port Location

Top

Side

	Maximum Flow Rate Maximum Flow Rate

	Relief Port Connection Type Relief Port Connection Type

Vent

	Shape Shape

	Straight

	Removes Particle Size Down To Removes Particle Size Down To

40 microns

90 microns

1,190 microns

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29 Products

About Noise, Filtration, and Flow Ratings

Weather-Resistant Breather Vents

Shield outdoor pipe and tank openings from the environment. Also known as vent caps, these breather vents have screens to allow air flow while blocking debris. Use them to prevent excess vacuum and pressure in your equipment.

Style C has two outlets for greater flow.

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

					Screen
Style	Pipe Size	Ht.	Lg.	For Use With	Material	Construction	Mesh Size	Removes Particle Size Down To, microns		Each
NPT Female
Iron Body and Fitting
C	3/4	1 1/2"	4 11/16"	Air	Brass	Wire Mesh	16	1,190	0000000	000000
C	1	1 1/2"	4 11/16"	Air	Brass	Wire Mesh	16	1,190	0000000	00000
C	1 1/2	1 7/8"	7 11/16"	Air	Brass	Wire Mesh	16	1,190	0000000	00000
C	1 1/4	1 7/8"	7 11/16"	Air	Brass	Wire Mesh	16	1,190	0000000	00000
C	2	2 3/16"	8 1/4"	Air	Brass	Wire Mesh	16	1,190	0000000	00000

Breather Vents

Protect against excess vacuum and pressure in cylinders, gear boxes, enclosures, manifolds, and tanks. You can also use these breather vents to block debris from entering equipment.

Style H has a Buna-N O-ring for extra protection against leaks.

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

NPT Male
Style	Pipe Size	Thread Size	Max. Flow Rate	Max. Pressure, psi	Max. Temp., °F	Ht.	For Use With	Removes Particle Size Down To, microns		Each
Brass Body and Fitting
A	1/16	__	13 scfm @ 100 psi	150	300°	1/2"	Air, Inert Gas	90	0000000	00000
UNF Male
Brass Body and Fitting
A	__	10-32	6 scfm @ 100 psi	150	300°	3/8"	Air, Inert Gas	90	0000000	0000
H	__	10-32	1 scfm @ 100 psi	125	200°	7/16"	Air, Inert Gas	40	0000000	0000

Self-Draining Breather Vents

Minimize moisture buildup in enclosures. Also known as drain plugs, these breather vents have a small outlet that allows condensation to drain. They have a silicone O-ring above the threads for a tight seal. Install them at the lowest point of the enclosure. Breather vents meet IP66 for protection in washdown environments. Use them to prevent excess vacuum and pressure in cylinders, gear boxes, and tanks and to block debris from entering equipment.

Brass breather vents have good corrosion resistance.

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

NPT Male
Pipe Size	Max. Temp., °F	Ht.	Dia.	For Use With	Environmental Rating		Each
Brass Body and Fitting
1/2	320°	15/16"	1"	Air	IEC Zone 1 Groups IIC, IIB, IIA, IEC Zone 21 Groups IIIC, IIIB, IIIA, IP66, NEMA 4X	0000000	000000
1/4	320°	15/16"	11/16"	Air	IP66, NEMA 4X	0000000	00000

Key-Operated Air-Release Valves for Water

Max. Pressure: 150 psi
Temperature Range: 33° to 200° F

Turn the key to manually release air from radiators, heaters, and other hot water equipment. These valves have a vented relief port that exhausts discharge directly. Body is nickel-plated brass for good corrosion resistance.

Valve
Inlet						Replacement Key
Pipe Size	Location	Relief Port Location	Overall Ht.		Each		Each
NPT Male Inlet and Relief Vent
Nickel-Plated Brass Body
1/8	Bottom	Side	1"	0000000	00000	0000000	00000

Air-Release Valves for Water and Coolant

With Female Inlet

With Female Inlet
and Female
Outlet

With Female/Male or Male Inlet

These valves are often used to remove air pockets in cooling and heating systems to maintain consistent flow and prevent water surges that can damage equipment. All have a vented relief port to exhaust discharge directly.

Valves with female/male inlets have an inlet with both male and female threads, so they can be connected to both male and female adapters and equipment ports.

Horizontally mounted valves with a female inlet are used in pass-through systems where you need your water or coolant to move through the valve. They’re commonly used for overhead hot or chilled water heating mains.

NPT Female Inlet and Relief Vent

Inlet
Pipe Size	Location	Relief Port Location	Max. Pressure, psi	Temperature Range, °F	Overall Ht.		Each
Brass Body—Vertical Mount
1/8	Bottom	Top	50	33° to 240°	2 5/8"	0000000	000000
1/8	Bottom	Top	75	33° to 240°	4 3/8"	000000	00000
1/4	Bottom	Top	150	33° to 240°	4 3/8"	000000	00000
Brass Body—Horizontal Mount
1/8	Bottom	Side	50	33° to 240°	2 1/2"	0000000	00000

NPT Female Inlet, NPT Female Outlet, and Relief Vent

Inlet		Outlet
Pipe Size	Location	Pipe Size	Location	Relief Port Location	Max. Pressure, psi	Temperature Range, °F	Overall Ht.		Each
Brass Body—Vertical Mount
1/8	Bottom	1/8	Side	Top	75	33° to 240°	4 3/8"	000000	000000

NPT Female/Male Inlet and Relief Vent

Inlet
Female Pipe Size	Male Pipe Size	Location	Relief Port Location	Max. Pressure, psi	Temperature Range, °F	Overall Ht.		Each
Brass Body—Vertical Mount
3/8	3/4	Bottom	Top	125	33° to 353°	6"	0000000	0000000
1/2	3/4	Bottom	Top	150	33° to 240°	4 3/4"	000000	00000

NPT Male Inlet and Relief Vent

Inlet
Pipe Size	Location	Relief Port Location	Max. Pressure, psi	Temperature Range, °F	Overall Ht.		Each
Brass Body—Vertical Mount
1/8	Bottom	Top	50	33° to 240°	3 3/4"	0000000	000000
1/8	Bottom	Top	75	33° to 240°	4 3/8"	000000	00000
1/4	Bottom	Top	50	33° to 240°	4"	0000000	00000
1/4	Bottom	Top	150	33° to 240°	4 3/4"	000000	00000
1/2	Bottom	Top	150	33° to 240°	3 1/8"	0000000	00000
3/4	Bottom	Top	150	33° to 240°	3 1/8"	0000000	00000
1	Bottom	Top	150	33° to 240°	3 1/2"	0000000	00000
Brass Body—Horizontal Mount
1/8	Bottom	Side	50	33° to 240°	2 1/2"	0000000	00000

Air-Release Valves for Steam

Our only air-release valves for steam, these seal shut when steam enters the valve to prevent system contents from escaping through the relief port. They are commonly used to eliminate air pockets in steam mains and risers. All exhaust discharge directly through the vented relief port.

	Inlet
Max. Steam Pressure, psi	Pipe Size	Location	Relief Port Location	Temperature Range, °F	Overall Ht.		Each
NPT Male Inlet and Relief Vent
Brass Body
15	3/4	Bottom	Top	212° to 249°	6"	0000000	000000
125	3/4	Bottom	Top	212° to 353°	6"	0000000	000000