Silica Gel Barriers | McMaster-Carr

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17 Products

Moisture Absorbing Breather Vents

Keep moisture, dirt, and debris from entering your oil reservoirs. The silica gel inside these breather vents absorbs moisture from the air, preventing rust from forming inside your tanks. The gel changes from blue to pink as it becomes saturated, letting you know it needs to be replaced. A second filter blocks dust and other particles from getting inside. These breather vents allow air to flow in and out of your lubrication system, keeping excess vacuum or pressure from building up in cylinders, gear boxes, and tanks.

Nylon and Polycarbonate Body—NPT Male

Breather vents with a plastic body are clear, so a quick glance will tell you if the gel is saturated. Unlike steel versions, which can be rebuilt, the entire unit must be replaced when fresh gel is needed.

	For Tank Cap., gal.	Max. Flow Rate @ Pressure	Max. Temp., ° F	Ht.	Dia.	For Use With	Removes Particle Size Down To, μm		Each
Nylon and Polycarbonate Body with Nylon Fitting



	3/8	1 to 2	4.5 scfm @ 1 psi	200	4"	2 1/2"	Air, Inert Gas	3	3297T72	000000


	3/8	1 to 5	4 scfm @ 1 psi	200	5 3/8"	2 1/2"	Air, Inert Gas	3	3297T71	00000
	1	5 to 200	16 scfm @ 1 psi	200	6 1/8"	4 1/8"	Air, Inert Gas	3	3297T31	00000
	1	5 to 350	16 scfm @ 1 psi	200	8 1/8"	4 1/8"	Air, Inert Gas	3	3297T33	000000
	1	5 to 500	16 scfm @ 1 psi	200	10 1/8"	4 1/8"	Air, Inert Gas	3	3297T35	000000

Nylon and Polycarbonate Body with Check Valves—NPT Female

Image of Product. Front orientation. Contains Inset. Breather Vents. Moisture Absorbing Breather Vents, NPT Thread, Polycarbonate Body, Nylon Body, Female.

For washdown environments, select breather vents with check valves. These valves allow air to flow in and out, but close when liquids try to enter.

	For Tank Cap., gal.	Max. Flow Rate @ Pressure	Max. Temp., ° F	Ht.	Dia.	For Use With	Removes Particle Size Down To, μm		Each
Nylon and Polycarbonate Body with Nylon Fitting



	1	1 to 400	27 scfm @ 1 psi	200	4 11/16"	5 11/16"	Air, Inert Gas	3	3297T73	0000000


	1	1 to 600	26 scfm @ 1 psi	200	6 7/16"	5 11/16"	Air, Inert Gas	3	3297T74	000000
	1	1 to 800	25 scfm @ 1 psi	200	8 1/4"	5 11/16"	Air, Inert Gas	3	3297T75	000000
	1	1 to 1,000	24 scfm @ 1 psi	200	10"	5 11/16"	Air, Inert Gas	3	3297T76	000000

Steel Body—NPT Male


	Repair Kits

For an extended service life, use breather vents with a steel body. They are stronger than breather vents with plastic bodies and hold up better when exposed to chemicals. A window lets you check the color of the gel.

Repair Kits—No need to replace the entire unit when the gel is saturated—use rebuild kits to add fresh gel and to replace the window, filters, and gaskets.

	Vents										Repair Kits
	Pipe Size	For Tank Cap., gal.	Max. Flow Rate @ Pressure	Max. Temp., ° F	Ht.	Dia.	For Use With	Removes Particle Size Down To, μm		Each		Each
Steel Body



		2	1 to 800	85 scfm @ 1 psi	220	11 1/2"	10 1/8"	Air	1	3297T77	000000000	3297T771	0000000


		2	1 to 1,300	85 scfm @ 1 psi	220	13 3/4"	10 1/8"	Air	1	3297T78	00000000	3297T781	000000
		2	1 to 2,400	80 scfm @ 1 psi	220	18 1/4"	10 1/8"	Air	1	3297T79	00000000	3297T791	000000
		3	1 to 4,000	205 scfm @ 1 psi	220	19 1/4"	15 1/2"	Air	1	3297T81	00000000	3297T811	000000