Preventing Tank Syphoning

What is an Anti Syphon Valve, and how can it prevent fuel syphoning?

The valve, heroic as it is, can be fitted in any orientation but it must be installed at the lowest point in the suction line. This is because any leak that may occur at a lower level than the valve may well result in the valve opening because of the syphoning action.

The anti-syphon valve is incredibly adaptable. It will operate consistently for tank fuel levels that range from 0 to 7.5 metres (25 feet in old money) above the level of the pump, with more or less no change in the amount of pumping effort required. This means that even with a relatively low suction capacity pump, it would still draw fuel at a consistent flow rate from a large storage tank, irrespective of the fuel level in that tank.

Should you need to, it is also possible to adjust the flow rate that is permitted to pass through the anti-syphon valve so as not to overwhelm a pump. Because, after all, no-one likes an overwhelmed pump. To provide an example, if the pump is connected to a taller tank, the flow rate from the tank will naturally be higher than a single, commercial pump can dispense, because fuel will pass through the air separator mini-vent when the pump is running. By easily adjusting the anti-syphon valve, you can reduce the flow and eliminate this potential problem.

Is there an alternative to a syphoning valve?

A cheaper alternative to the anti-syphon valve would be to install a check valve, fitted with a spring to the tank outlet (ensuring the pressure rating of the spring is matched from the lowest point in the suction line to the top of the tank). For example, at a maximum height of 3.6 metres (12 feet), a 6psi (0.4 bar) spring is required to effectively hold back the fuel in the event of a leak from the pump or suction line leak. To be fair, when the tank is at or near total capacity, this anti-syphon method works well because the pump requires very little effort to overcome the spring-loaded valve due to the “assisting” pressure created by the height of the fuel level.

However, the disadvantage of using an angle check valve is that, as the tank fuel level drops, the pump has to work harder to draw fuel up through the suction line inside the tank and then through the spring-loaded check valve. This can result in lower flow rates and significantly more “wear & tear” on the pump itself. Of course, this naturally leads to a shorter lifespan.

Why do I need to prevent fuel tank syphoning?

Preventing tank syphoning is the best practice in the industry because it protects tank owners from the associated risks. Fuel spills can be costly, not only in terms of expensive clean-ups but also in terms of the environmental damage they can cause. The increased slip hazards for staff and the cost of the lost fuel both make preventive measures the sensible option.

Find out more

If you’d like to find out more or talk to us about the best solutions and more information on preventing tank syphoning for you and your customers view our anti syphoning valve today: Anti-Syphon Valve for Diesel or Biodiesel – Hytek GB Ltd