Hot Water and Kränzle Pumps

Kränzle pumps can take an inlet water temperature of up to 160 degrees. Though the pump will accept water at that high temperature, it will need more maintenance than if cold water is used exclusively. Where normally a pump being used every day would need new packing once a year, when pumping 160° water the pump will require new packings every three to four months.

Kränzle pumps self-prime. Since the pump is actively seeking water, it will suck in air if sufficient water is not provided, thus cavitating the pump. This can become a greater problem if the inlet water is hot. Hot water, as it approaches steam, forms air bubbles. Thus hot water under pressure will begin to introduce air bubbles into the pump. These air bubbles will cause cavitation resulting in early wear of packings and valve o-rings. To prevent this from happening, the inlet water must have a positive inlet pressure - the more the better. This will insure sufficient water is taken into the pump and cavitation is prevented.

The other problem hot water causes is condensation. The hot water will raise the temperature of the pressure washer pump considerably. When the unit shuts down and begins to cool, water vapor condenses in the transmission housing, and in the case of electric motors, in the motor housing. The water that condenses out of the water vapor mixes with the oil in the transmission housing, making the oil a milky white. Often the operator believes the cause is water passing through the packings into the transmission housing. However, this is not possible because there is a small slot at the bottom of the pump where the pump head is fastened to the transmission housing, where the water would drip out before reaching the transmission housing.

Oil can absorb up to 5% water before its performance is seriously degraded. The only solution to the problem of water building up in the transmission housing is to change the oil frequently. In the case of water condensing in the electric motor casing, the way to fix the problem is to drill a hole in the bottom of the motor casing, making sure the hole is not so deep as to penetrate the motor windings. This will allow the build up of water to drain out of the motor housing.

Remember when using units equipped with the Kränzle pump, that though the units can run in by-pass for an extended period of time (more than an hour for AQ gas, many hours for the APG electric), this is only the case with cold water. When using hot water the by-pass time drops dramatically as the inlet temperature reaches the maximum.

Pumping salt water through Kränzle pumps

Over time, salt water will damage brass pump heads like those used on Kränzle pumps. Seawater attacks the zinc in the brass, creating small holes around the valve seats. Critical factors to consider are the percentage of salt content and the water temperature. When salt concentration is less than 5% and water temperature is less than 75° F, the pump head should last from 2-5 years. So, using salt water through your Kränzle pump voids the ten-year pump head warranty. Nonetheless, Chesapeake Bay crabbers have used Kränzle pressure washers successfully for over five years at a time with no reported problems. Tip - when pumping salt water through your pressure washer, make sure you flush the pump out with fresh water after you are done. At the very least, pump the pump head dry if no fresh water is available.

Over-filling the transmission housing