Forespar Vented Loops

Forespar Marelon Vented Loops: Corrosion-Free Marine Plumbing Solutions

Forespar vented loops are molded from Marelon, a proprietary marine-grade glass-filled engineered polymer that has revolutionized marine plumbing since the company began manufacturing these components in the 1980s. These anti-siphon devices serve a critical safety function aboard any vessel, and Forespar's commitment to using advanced materials rather than traditional bronze has made their vented loops the preferred choice for both custom yacht builders and production boat manufacturers worldwide.

What Makes Forespar Vented Loops Different

Unlike traditional metal components, Forespar's Marelon vented loops will not corrode, eliminating the galvanic corrosion and electrolysis problems that plague bronze marine plumbing in harsh saltwater environments. Forespar's Marelon plumbing system components use lighter materials in designs that eliminate corrosion and electrolysis, and continue to grow in use by fine yacht builders around the world. This corrosion resistance translates to longer service life and more reliable operation, especially in systems that may sit idle between uses.

The engineering behind these vented loops goes beyond just material selection. Each vent cap features a duckbill-style one-way valve designed to seal properly even if particulate matter is present in fluids, making them particularly well-suited for marine toilet applications where debris is common. The simple yet effective valve system incorporated into the top of each loop allows air to enter the line when not in use, breaking the siphon effect that could otherwise flood your vessel.

Proven Technology for Critical Marine Systems

Vented loops are commonly used in marine toilet systems and engine cooling systems, two applications where back-siphoning poses serious risks. Forespar Marelon vented loops keep water and other fluids from siphoning back into tanks or into the bilge by allowing air to enter the line and breaking the siphon effect. This prevents potentially catastrophic flooding scenarios that could sink a vessel or damage expensive engine components.

Forespar offers these anti-siphon valves in multiple sizes to accommodate different plumbing configurations, from 3/4-inch to 1-1/4-inch hose connections. Each unit features NPSM (National Standard Free-Fitting Straight Mechanical Pipe Thread) parallel threads that are specifically designed for marine applications, ensuring proper sealing when installed with appropriate marine sealants or bedding compounds.

Maintenance and Longevity

While Marelon's corrosion-free properties reduce maintenance compared to bronze components, Forespar recommends activating the valves regularly and lubricating with winch grease, Lanacote, or water pump grease twice a year. The material is UV-stabilized to resist deterioration from sunlight exposure, and replacement vent caps and optional hose barb assemblies are readily available for long-term serviceability. For boat owners seeking reliable marine plumbing components from a trusted manufacturer, explore the full range of Forespar products designed to make boating safer and more dependable.