Universal Plastic Tank Shut-Off Valve – Available in 3 Sizes (1/2", 3/4", 1")

This universal plastic valve is designed to reliably shut off flow from fuel or water tanks. Thanks to the durable polymer material it’s made from, the valve won’t rust and can withstand prolonged contact with gasoline, diesel, oils, or saltwater. This makes it suitable for a wide range of uses – from boat fuel systems to RV water supplies.

Available Sizes:

• 1/2" (approx Ø15 mm inner bore) – the smallest size, suitable for small tanks and low flow rates. Ideal for portable jerrycans up to ~20–30 liters or outlets with a small diameter where fine flow control is needed. Recommended for small boats (3–5 m) and tanks for auxiliary equipment (e.g., generators).
• 3/4" (approx Ø19 mm) – a medium size covering standard applications. Good for tanks around 50–100 liters, typical of mid-sized boats (5–7 m) or water tanks in caravans. It provides a balanced flow – fast enough filling without being excessively large.
• 1" (approx Ø25 mm) – the largest of the three, meant for higher flow and larger tanks. Advised for tanks >100 liters, such as main fuel tanks on yachts, water tanks of ~150–200+ liters, or holding (waste) tanks. This size suits boats over ~7–8 m, where systems require a freer flow.

Design & Installation: All variants share the same design – an internal ball valve mechanism operated by a lever handle that rotates ~90° from fully closed to fully open. The handle is easy to grip and allows quick reaction when you need to stop the flow. Installation depends on your tank: the valve can thread onto a tank’s outlet or be secured with a nut/clip – depending on the tank’s design. The valve features built-in seals (e.g., rubber O-rings) to prevent leakage at the connection. The 1/2" and 3/4" sizes often correspond to common tank thread standards (like BSP or NPT), while the 1" may also come with a flange option – ensure you select the correct interface for your tank.

Applications & Advantages:

• Boat Fuel Systems: This plastic valve can serve as a manual shut-off on the fuel line between a tank and the engine. For example, on portable external tanks for outboard engines, adding a 1/2" (close to 3/8" hose ID) or 3/4" valve makes it easy to switch tanks and prevents fuel spills when disconnecting.
• Water Tanks & Systems: In caravans and RVs, this valve can be used on the outlet of the freshwater tank for easy draining during winterization or maintenance. At home, it’s useful for rainwater barrels or IBC totes where a simple tap is needed. The plastic material is safe for water and won’t contaminate the liquid.
• Waste Holding Tanks: For grey water (sinks, showers) or even black water (toilet) tanks on board – the plastic valve is resistant to chemicals found in typical treatments. The large 1" size is helpful for quick discharge when emptying the tank at an appropriate facility.
• Universal Spare Part: One advantage of having a couple of these plastic valves in different sizes is that they are inexpensive and do not corrode. Even if not installed permanently, they can serve as spares – for instance, if a metal seacock corrodes or freezes, a plastic valve can temporarily replace it. Many crews keep one or two in their toolkit for emergencies.
• Safety & Ease: A plastic valve eliminates sparking (important around fuel) and is a dielectric (non-conductive), meaning it won’t promote galvanic corrosion between dissimilar metals in your system.

Recommendations: When choosing a size, match the diameter of your tank’s outlet and the flow you need. Always use thread sealant (like PTFE tape or appropriate sealant) on threaded connections to prevent any seepage. Avoid over-tightening during installation – plastic threads should be snug by hand; if using a tool, apply gentle pressure.

The maximum working pressure for these valves is generally limited (they’re intended for gravity-fed or low-pressure systems) – do not use them on high-pressure lines. Also avoid liquid temperatures above ~70°C (158°F). In normal use for fuel and water, the valve will provide long, trouble-free service; only the seals might need replacement after years of use.