Valve & Filling

What Is a Flexitank Valve and Filling System For?

Flexitank filling and discharge take place through connection points made up of a flanged collar welded onto the bag and a capped valve that screws onto that collar. These valves allow liquid to be transferred into the bag in a controlled way during filling, and discharged without leaks during unloading.

Top Valve (Filling) and Bottom Valve (Discharge)

In flexitank systems, filling and discharge are usually carried out from different points. The top filling valve sits on the upper section of the bag, near the container door, and lets a pump push liquid into the bag. The bottom discharge valve is positioned near the bag's front lower corner; this location takes advantage of gravity during discharge, allowing the liquid to drain with little or no pump assistance. In some configurations, both filling and discharge are done through the top valve; the choice depends on the equipment available on site and the hose connection height.

Connection Design

The valve consists of a reinforced flanged collar welded to the bag surface and a screw-on cap/plug that seats onto that collar. The cap protects the valve from impact damage during transport and prevents accidental spillage; it is removed before filling or discharge and connected to a suitable hose adaptor.

Filling Process

Before filling, confirm that the container and bracing system are correctly installed, carefully remove the valve cap, and connect the pump hose to the adaptor with a leak-tight seal. Filling should be done gradually so the bag spreads evenly inside the container; a sudden, high-pressure fill from a single point can over-stress one area of the bag.

Discharge Process

During discharge from the bottom valve, liquid flows toward the valve by gravity; positioning the container on a slightly inclined ramp, or tilting it up at the front with a forklift, can improve discharge efficiency and help empty the bag completely. Higher-viscosity liquids may need pump assistance for full discharge.

Common Issues

• Loose valve connection: Failing to fully tighten the cap or hose adaptor causes leaks during filling and discharge.
• Using an incompatible adaptor: Forcing on a hose adaptor that doesn't match the valve can damage the flanged collar.
• Incomplete discharge: Uneven folding of the bag inside the container can block the bottom valve's full access to the liquid, leaving residue at the bottom.

Choosing the Right Equipment

The hose diameter and adaptor thread used for filling and discharge must fully match the valve's flange size. Trying to force a seal with an incompatible adaptor and gasket can damage the connection point and cause unexpected leaks during filling or discharge; businesses that work with more than one flexitank brand on site are advised to check their adaptor set in advance.

Maintenance and Inspection

Before filling, visually inspect the valve and cap for cracks or deformation. Filling through a damaged valve carries a risk of leakage in transit and can result in the unnoticed loss of a significant portion of the cargo.