The following is standard procedure for introducing a pump into a molten metal bath:
WARNING – GRAPHITE CONTAINING MOISTURE MAY EXPLODE IN MOLTEN METAL! ALWAYS REFER TO THE MANUAL THAT SHIPPED WITH YOUR MOLTEN METAL PUMP FOR ADDITIONAL SAFETY INFORMATION.
IF YOU SEE THE PUMP “BUBBLING” AT ANY POINT IN THE FOLLOW PROCEDURE, LIFT THE PUMP UNTIL THE BUBBLING STOPS. AFTER THE BUBBLING HAS STOPPED, RESUME THE INSTALLATION FROM THE BEGINNING.
The typical sequence is as follow:
- Lower the pump over the melt to within 10cm or 2in of the surface of the melt and allow the pump 45 minutes to stabilize (skip this step if the pump has been preheated in a Preheat Station for 2+ hours at 250-300F or 120-150C.)
- Lower the pump so the entire bottom of the base surface is in full contact with the surface of the melt and wait 20 minutes.
- Lower the pump so that half the base is submersed (leaving the top half of the base and the riser/posts exposed) and wait 15 minutes.
- Lower the pump slowly in several 3 to 4 inch (or 8 to 10 cm) increments at a time, waiting 5 to 10 minutes at each increment for thermal stabilization.
- Before energizing the pump on, manually rotate the shaft clockwise to ensure that it spins freely.
This procedure minimizes the potential for thermal shock damage and maximizes safety for the maintenance personnel.
Initial pump startup will be covered in a subsequent post.