6" Backwater Valves
Mainline Straight Fit Extendable Backwater Valves in ABS and PVC
These 4" and 6" Backwater Valves drop less than 1/2" from Inlet to Outlet
The newly crafted Mainline ML-SF668 Extendible Backwater Valve is a great choice for new and retrofit situations where a 6" valve is needed.
3" ML-SF334 & 4" ML-SF446 Extendable Backwater Valves are also available now.
The STRAIGHT-FITTM valve is Mainline’s latest addition to the Extendible Backwater Valve series. This is a normally-closed gate automatic backwater valve design.
STRAIGHT-FITTM valves come in 4” and 6” (both models are now available) and have features that will make STRAIGHT-FIT one of the most asked for valves in the industry!
Produced in both Schedule 40 PVC and ABS, the STRAIGHT-FITTM has a body that is extendible to whatever depth you require by simply gluing a riser of Schedule 40 (like material) pipe into the valve body and extending to ground level. The 6" valve uses an 8" diameter riser and the 4" valve uses a 6" diameter riser. This sourced on the jobsite and cut-to-size on site riser is to be capped with an air-tight cap.
The normally closed gate is glued to a piece of ¾” PVC pipe (sourced on the jobsite and cut on site to proper length) to form a tool to extract the gate from the valve body.
Mainline has integrated "Smart-CURVE"TM technology into these valves which serves as a dual function; First, this system features a "curved gate" that is designed to allow a sewer rodding snake to feed and retract without catching on the gate itself! The other added benefit is a "Smart-CURVE"TM "cleat insert" in the body that will ease and guide the retrieval of the snake without hanging up on the body
The STRAIGHT-FITTM also features an optional Test Gate that can be used to pressure test the system or to isolate the property for whatever purpose; non -payment of services, vacation properties, servicing etc.
Patented USA 4503881 and Canada 1196835; other patents pending. ASME A112.14.1-03, CSA B181.1-02 and B181.2-02, UPC US 8.096.318 and Canada 7.757.706 and 2.414.634.
Optional 3", 4" and 6" Test Gates offer test mode or 100% Manual Seal
Mainline Fullport Backwater Valves offer the right solution for your sewer backup problems. SPECIAL OFFER: Mainline Backwater Valve "Combo" with Access Box ($99.00 value if purchased separately) Valves without Access Box are also available with a slight shipping discount in the price.
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Be sure to check with the plumbing authority in the municipality in which your valve is to be installed to insure that your installation is in compliance with local code, and be sure have your valve inspected by your local plumbing inspector after installation. Inspect your valve frequently; the Backwater Valve through its clear plastic housing top, and the Adapt-A-Valve, by removing the gate cassette.
Pipe end-to-end, the Adapt-A-Valve takes up 6" of run in your line and the outlet is 1-1/2" LOWER than the inlet, so in just 6" the level of the pipe at the outlet side needs to be 1-1/2" lower.
Pipe end-to-end, the Backwater Valve takes up 12" of run in your line and the outlet is 3/4" LOWER than the inlet, so in just 12" the level of the pipe at the outlet side needs to be 3/4" lower.
Depending upon the amount of slope in your line (2% minimum is required for proper operation), you may need to replace several feet of pipe downstream from the valve to average out this "loss" of fall.
NOTE: New Straight-Fit and ML-FR4 require less slope. (refer to detail pages for these products)
Mainline Valve Warranty
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