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Dosing Up Hill & Down Hill

A common question we have is why does liquid come out of the discharge hose from our Chemical Dosing Pump, when theDosing Pump is not running?

Further investigations reveal this problem is caused by the liquid pumped being higher than the dosing pump and the discharge point being lower than the dosing pump if the solution is syphoning.

The ball valves in many small pumps operate by gravity and will allow the liquid to flow through the pump head with this kind of installation. When the pump is in service with the injection connected and installed into a line with 3 bar pressure, there is however, no problem.

How do I fix this problem?

This problem occurs when dosing down into pits or sumps usually used for pH adjustment. As the chemical reagent can syphon from the dosing tank into the pit or sump.

A customer would find that the pH had dropped to a low value when there was no production. The Red Dosing Pumps were mounted on a flooded suction from an IBC, which dosed into the sumps below ground level, hence the dosing was downhill. The problem was that the acid was slowly syphoning through the Red Dosing Pump.

The answer is to use our multi function valve AC-VM-PVDF. This clever little device screws on to the outlet valve of the Red Dosing Pump via a special connector and an outlet hose to go back into the chemical container.

The AC-VM-PVDF has several functions. As a safety valve, to relieve the pressure back into the chemical container in the event of the discharge becoming blocked, or someone fitting an isolating valve, which is not recommended. As a loading valve, to give the pump some pressure to work against. As an anti syphon valve, to prevent syphoning when dosing down hill. As a priming valve, to allow the pump to pump back into the chemical container, until the head is full and the valves are wetted. And finally, as a drain valve, to allow the dosing hose to be drained before disconnecting the pump for maintenance.

AC-VM-PVDF valves are adjustable from 0-5 bar back pressure in PVDF with PTFE diaphragm and available with either Viton or EPDM seals. 

If you require more information on the AC-VM-PVDF multifunction valves or other dosing accessories, please contact our Sales Office.

dosing up and down hill

Dosing Pumps

Dosing Pumps

Water Treatment, Effluent Treatment and Process Control applications often include a requirement to add chemical reagent to a process. There is significant variance in the type of chemical reagent to be added, the flow rate, pressure and the nature of the control methodology. Our dosing pump range is designed to cover the full spectrum of control types, dosing rates and to ensure compatibility with a wide range of chemical reagents. 

Each metering pump in our dosing pump range is designed to provide accurate chemical delivery, to run continually, and to provide many years of reliable service in process control applications.

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Multi-Function Valves

Multi-Function Valves

We offer a range of loading valves and multifunction valves for use with chemical dosing.

Loading valves have a manually adjustable pressure for the dosing pump to work against, acting as an anti-syphon valve as well as ensuring that a dosing pump has a  consistent pressure to work against.

The multi-function valves offer the ability to act as a loading valve / anti-syphon valve as well as a safety valve  / pressure relief valve and available with a range of wetted parts to suit most chemical applications.

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