Forespar Marelon Vented Loop Anti-Siphon Valve

The Forespar Marelon Vented Loop Anti-Siphon Valve is a marine plumbing safety device. It stops back siphoning, which can flood or sink a boat. Back siphoning can happen through any tank, engine, head or bilge system that uses a through-hull intake. The vented loop, also called a siphon break or anti-siphon valve, lets air into the line when the pump shuts off. That breaks the siphon before water can flow back into the boat.

Key Features:

• Molded in glass-reinforced Marelon, so neither the vent nor the loop will corrode
• Valve in the top of the loop lets air in when the line is not in use and seals as fluid passes through
• Duckbill one-way valve is designed to seal properly even when particulate matter is in the fluid
• Stops fluids from siphoning from tank to tank or back into the bilge
• Commonly used on marine toilet (head) discharge, bilge pump outlets, engine cooling and aqua-lift systems, generator sets, air conditioners and ballast tanks
• Suitable for water and similar fluids, but not for fuels
• Optional vent barb assembly allows venting to the outside of the hull through a small-diameter hose

Install the loop above the waterline. Forespar says it is the world's largest producer of marine vented loops and offers the widest range of sizes. Choose the option that matches your hose or plumbing size.