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Maintenance Of Self Serve Soap Tanks and Hydrominders

A look at the maintenance of your self serve soap tanks and Hydrominders. This may also be relevant to some automatics that use Hydrominder tanks.

A Hydrominder is basically a solenoid operated by a weighted float. As the soap level lowers in the tank, the float has enough weight to pull a magnet down the plunger stem causing the diaphragm to open. As the tank fills the float rises, and a spring under the magnet returns to the upper position losing the diaphragm. There may be a mesh strainer fitted to the incoming water supply. These are sometimes located on the inside of the soap tank in a swivel union. The water coming out of the valve then passes through an Eductor. The Eductor generates the venturi which draws the soap or wax concentrate out of the drum through a metering tip, either screw or push in type. The soap solution then flows down the discharge hose into the tank. In the discharge hose there is a flow restrictor which is important to the operation of the Eductor, so it is important that this hose is in place. If this hose comes off, the Eductor/venturi will not operate correctly. In the case of a Prowash/SuperSat installation the products that use a dual Eductor system will have an anti siphon valve built in. A single Eductor system may need to have an anti siphon hole drilled in the discharge hose. This hole should be approximately 3mm and located downstream of the flow restrictor, but above the full level of the soap tank. This will break the siphon and lessen the chance of solution leaking back into the soap drum and diluting it. Your soap tank should also have a strainer on the outlet of the tank to prevent foreign objects potentially fouling solenoids or check valves.

If you are experiencing problems with soap application in the bays then the tanks are a good place to start looking. Check all the tank outlet strainers to make sure they are clean and not blocked. Pull down on the floats to operate the Hydrominders and check for correct water flow. If one product has less flow than the others it may be a blocked inlet strainer or damaged diaphragm in the Hydrominder. A reduced water flow can result in weak dilution in the tanks and poor results in the bays. If these are ok check that you have the correct size metering tip and it is free of obstruction. Check the foot valve in the soap drum too, the soap should not drain back down the line to the soap drum. The foot valve may also become clogged preventing soap being pulled up the suction line. It is good practice to look over all of these aspects of your tanks every 6 months or so. Clean out each tank and all strainers. Check the operation of the Hydrominders including the tips and foot valves in the soap lines. Sites should carry spare strainers, foot valves and tips as well as Hydrominder valve kits.