Maintenance Pumps and Typical Use Cases
Zinc Maintenance Pump Ready for Rebuild
About 10% of molten metal pumps are used exclusively for maintenance applications. It is not uncommon to use a maintenance pump once every year to eighteen months. Long term storage of a pump, especially a pump that has been exposed to molten metal, requires special considerations.
Maintenance pumps tend to undergo rougher duty than continuous circulation and transfer pumps. As the furnace is emptied, the pump base is lowered to the bottom of the well where contamination accumulates. This can be especially rough on impellers and shafts. For dedicated dross removal (such as in zinc galvanizing applications), specialty dross pumps may be necessary.
Use-Case Scenarios:
Emergency Bail-Out Pump - Power outages and emergency furnace maintenance sometime require immediate pump-outs. Ideally, an emergency pump is maintained in a pre-heat station and can be ready to use in 15 minutes or less.
Planned Maintenance - Planned maintenance allows scheduling of the pump preparation well in advance. This means that the pump does not need to be stored in a preheat station.
Alloy Changes - When an alloy change is necessary, the metal from the bath is typically pumped into sows for storage
Maintenance Pump over Zinc Hot-Dip Pot
The pump shown in this picture was used to perform an alloy change to a lower aluminum content alloy. The pot was emptied in less than an hour into sows that were reused in a neighboring facility.
In case of emergency situations, like unplanned power outages, an emergency pump can assist in emptying the furnace before the metal freezes and damages the furnace liner.
Typically, emergency pumps are fitted with an air motor so the pump can be operated on stored compressed gas during power outages using either the house air/nitrogen supply or bottled gas.
In between uses, the pump will need to be serviced and stored to ensure it is ready for future maintenance needs. See the following articles for additional information:
Pre-Storage Pump Inspection - Maintenance Pumps
Preparing the Pump for Storage - Operational Assessment and Removal from Metal