The TA770-R Breather Valve has separate and distinct settings for both pressure and vacuum relief.  It has a flow rate of 10.0 to 25.0 scfm at 1.5 psi above the valve setting, making it suitable for large containers and similar applications up to 208 cubic feet in volume.  Standard settings range from 0.5 psid to 5.0 psid reseal pressure.  The lower the setting, the higher the flow rate.

The TA770 Breather Valve is tamper-proof and requires no field maintenance. Corrosion-resistant materials are used throughout. The valve seal is made of silicone rubber.  The spherical valve seat is Teflon coated for easy "break-away" action even after prolonged storage.

The manual release push button is used to equalize the pressure or vacuum differentials in order to make opening the container easier. The button is recessed in the cover to protect it from damage and eliminate the possibility that an adjacent container might press the button and inadvertently cause the valve to remain open.  A unique feature of the push button is a light duty spring under the cover, separating the button from the vacuum stem, which must be overcome before the button opens the valve.

A gasket, washer and hex nut for mounting are provided with each valve.  RFI/EMI shielding is also available.

The TA770 Breather Valve's unique cover and dust baffle provides superior protection from sand and dust intrusion.  Additionally, the cover makes this valve well suited for high-pressure hose down applications.  When compared to a screened valve such as AGM's TA238 Breather Valve as well as competitors' valves, the TA770 Breather Valve allows virtually no water to pass when subjected to a high-pressure water stream.  The TA770 Breather Valve has been tested to the NEMA 250 5.7 high-pressure hose down test; contact AGM's Engineering department for more information.

The TA770 valve is offered in two types: “Cracking” and “Reseal”.  Cracking valves are rated by cracking pressure (the pressure at which the valve has opened enough to flow 1 cubic centimeter per minute) and the flow rate at 0.5 - 2.0 psi above the cracking pressure.  Reseal valves are rated by reseal pressure (the pressure by which the valve is guaranteed to close after it has cracked open) and the flow rate at 1.5 psi above the reseal pressure. 

Note that whether you are specifying a reseal valve or a cracking valve, the flow rate is usually the most important parameter when selecting a valve: per SAE Specification AS27166, you should select a valve with a flow rate of at least 12% of the container volume per minute at a pressure less than the container’s pressure rating.  For instance, when choosing a valve for a container with a volume of 10 cubic feet that can withstand a pressure of 2 psi, the recommended valve would flow 1.2 standard cubic feet per minute (SCFM) at 2 psid or less pressure differential.  While at first glance it may appear that a valve with a crack point of 2 psi would be appropriate for this application, remember that the flow rate at crack is very low (1 cc/min) and therefore would very likely not provide adequate pressure relief.  Refer to Theory and Characteristics for more information on selecting a breather valve.

Flow rate versus pressure curves are available for some valves.  Contact AGM’s Engineering Department if you require this information.

Materials and Finish: Housing, nut and washer are aluminum. Housing and nut are anodized and washer is alodine conversion-coated. Gasket material is per A-A-59588, Class II, Grade 60. Torque value for installation: 80 in. - lbs. (9.0 N•m)  Weight: 0.40 lbs. (181 grams)

Mounting Requirements: A gasket, washer and hex nut for mounting are provided with each valve.
Mounting hole diameter: 2.050 ± 0.020 (52 ± 0.50 mm)
Installation torque: 80-90 in. - lbs. (9.0-10.0 N•m)
Maximum wall thickness: 0.85 (22 mm)
Minimum wall thickness: 0.001 (0.03 mm)
For threaded boss installation: 2.00-18 UNS-2B; 2.050 ± 0.020 (52 ± 0.50 mm) diameter X 0.085 (2 mm) minimum deep counterbore required for thread relief.

Contact AGM's Engineering department for information on NEMA and IP ratings.