77_1The MainGuard #77 Blow-Off provides the best in performance and value. Designed and engineered specifically for flushing, the #77 provides excellent flow rates for improving chlorine residual levels and flushing disinfection byproducts (DBPs) to keep water safe for consumers. The unique valve design allows for a full clear-channel flow (see illustrations) that is superior to other blow-offs for moving water and passing debris easily. The #77 plunger is also designed to allow for throttling the flow of water while at the same time covering the drain hole to avoid unnecessary erosion. The MainGuard #77 comes standard with all brass principle working parts, nozzle sizes up to 2 ½” NST, traffic break-away, self draining non-freezing, 2” FIP vertical (straight) inlet and locking security cover standard. The MainGuard #77 is fully serviceable from above ground. Certified to NSF/ANSI 372.


• Depths of bury over 3', per 6"
• 90° horizontal (side) inlet
• 2" MJ inlet iron w/ epoxy coat
• 2" MJ inlet all brass adapter