CHEMICAL FEED / WATER TREATMENT

Why won’t my chemical feed diaphragm pump the chemical?

There are several reasons why a chemical feed pump won’t pump. The best place to start is to consult the trouble-shooting guide that comes with your pump. There are two basic things a pump of this type needs for proper operation. First, it has to be able to draw the chemical into the diaphragm housing and second it has to be able to push the chemical into the application point. When investigating the cause of the failure pump, you may want to start at the suction side of the pump first. Verify that the foot valve (if your pump comes with one) in the solution tank is clean and not clogged with debris. The foot valve also has to remain in the vertical position in order for the internal check valve to function properly. Next, inspect the tubing and connections for leaks or cracks. Remember, a leak on the suction side of your pump may be invisible. The connection should only be hand tightened. Never use a wrench. Over tightening may result in distorting the seals, which will interfere with the function of the check valves. Check for leaks around the diaphragm housing. A hole in the diaphragm can prevent it from pumping.

Next, check the discharge side of the pump for leaks. Again, verify that the connections haven’t been over tightened and that the seals haven’t been distorted or smashed down too far. The discharge tubing and injector should be checked next. Inspect for crimped tubing that would prevent the chemical from reaching the application point. If your pump came with an injector, it should be mounted on the underside of a horizontal pipe in a vertical position for the internal check valve to function correctly. The pressure of the line you are pumping into should be checked to verify the pump is adequately sized for this pressure.

Some chemicals have a natural tendency to off gas. This off gassing causes air gaps in the tubing, which can cause a pump to lose its prime. A bleed valve with degassing capabilities is recommended. This degassing valve mounts on the discharge side of the pump. It has tubing that attaches to the side of the valve and can run back to he solution tank. A knob or adjustment screw (depending on the brand of your pump) can be adjusted to allow a small portion of the chemical to constantly pump back to the solution tank. This constant priming should bleed off any trapped gasses in the tubing. If this still doesn’t alleviate the problem, please consult the Technical Department at USABlueBook.