Subject: PERISTALTIC PUMPS WHICH DRIBBLE WILL DAMAGE MACHINES (OURS AND COMPETITORS ALIKE)

This bulletin is being issued because there still seems to be a lack of understanding about the following subject:

It is not good enough to merely inject the chemical onto a surface that will be subsequently flushed or wetted sometime during the wash process. This is because the "culprit" is the chemical which dribbles out later. The damage occurs when the residue of a chemical (even a diluted chemical) dries on a surface - as what happens after a chemical dribbles out of the delivery tube following the last wash cycle for the day. As the chemical dries, the water content evaporates - leaving a deposit of a very concentrated chemical which is then free to attack the host surface throughout the night (or over the weekend) or until the machine is next returned to service.

Please see our revised page MSSM0213AE (below) which has been modified to eliminate the drilled holes in the cup.



MSSM0213AE/85427 (1 of 1)

RULES FOR THE FIELD INSTALLATION OF PUMP-TYPED LIQUID SUPPLY SYSTEMS

Pellerin MILNOR Corporation does not guarantee machines against damage from corrosion caused by improper installation and/or operation of pumped-type liquid supply systems:

1) Always install the pumping unit lower than the discharge end of the chemical delivery tube as shown in the figure, below right. This will prevent any excess concentrated chemical from dripping out of the tube and onto dry, unprotected machine surfaces when the machine is idle. Merely putting a "drip loop" in the delivery tube won't help much. (This might reduce the dribble a little - but not enough to prevent damage.) The real solution is to install the pumps below the discharge end of the delivery tubes - so excess chemical won't dribble out of the tube long after the pump stops.

2. If the machine is also equipped with a flushing supply injector:
(a) Always wire the new system so the appropriate flushing valve also operates whenever chemical is being injected. This will dilute the concentrated chemical with obvious advantages. If possible, the water flushing valve should remain on for a minimum of 30 seconds after the longest injection time for that chemical.
(b) Always inject the chemical into a plastic cup (and direct the flushing water into the same cup). This way, any chemical that dribbles out of the tube after the pump stops will be diluted by the water remaining in the cup.

3. Never inject any concentrated chemical directly onto any metal, rubber, or plastic surface of the machine other than the plastic cups provided.

IT IS NOT ENOUGH TO MERELY INJECT THE CHEMICAL ONTO A SURFACE THAT WILL BE SUBSEQUENTLY FLUSHED OR WETTED SOMETIME DURING THE WASHPROCESS. THIS IS BECAUSE THE "CULPRIT" IS THE CHEMICAL WHICH DRIBBLES OUT LATER. THE DAMAGE OCCURS WHEN THE RESIDUE OF A CHEMICAL (EVEN A DILUTED CHEMICAL) DRIES ON A SURFACE - AS WHEN A CHEMICAL DRIBBLES OUT OF THE DELIVERY TUBE AFTER THE LAST WASH CYCLE IS FINISHED. AS THE CHEMICAL DRIES, THE WATER CONTENT EVAPORATES - LEAVING A DEPOSIT OF A VERY CONCENTRATED CHEMICAL WHICH IS THEN FREE TO ATTACK THE HOST SURFACE THROUGHOUT THE NIGHT (OR OVER THE WEEKEND) OR UNTIL THE MACHINE IS NEXT RETURNED TO SERVICE.

The only realistic solution is to make sure that the discharge end of each chemical delivery tube is above the pump so excess chemical left in the tube after the pump stops cannot dribble out later.