The mill operator has to check equipment during the normal course of duties in order to be sure that all items are operating normally. In this way will be prevented breakdowns, disruptions to operations and maintenance costs to a minimum. Process pumps must be inspected at least every 2 hours for potential problems. This operator task provides information helpful in diagnosing both mechanical and operational pump problems. It is common for a process pump system to consist of on line and standby pumps. The operator may find that a pumping problem is remedied by switching to the standby pump. This method serves as a good diagnostic tool for resolving pump problems. The procedure is described below and when the problem is serious and cannot be solved immediately, the maintenance department must be notified. Visually inspect the pump and verify that the guards are in place and secure
· If the pump is fitted with a packing gland, as opposed to an expeller seal, ensure that there is a minor drip or leakage of liquid along the shaft. This liquid is required for the cooling and lubrication of compression packing systems. If the pump is fitted with an expeller seal: Ensure that there is no liquid leakage along the shaft. There must be no leakage of liquid along the shaft where mechanical seals are fitted
· The pumps are fitted with gland seal water connections. During operation, a flow of gland seal water must enter the pump through the gland to prevent slurry from entering the gland. If slurry enters the gland, it can destroy the pump sealing system, shaft, and/or shaft sleeve. Check the gland seal water pressure gauge to ensure that the gland seal water pressure is normal, higher than the pump discharge pressure. Ensure that the manual gland seal water shutoff valve is fully open. Check the local gland seal water flow meter, and ensure that water is flowing to the pump gland
· Look for signs of end float, axial movement of the shaft. Excessive end travel is indicative of improper fitting of the thrust bearing, thrust bearing failure, pump end problems, and/or motor problems.
· Look for evidence of unusual vibration, and listen for noises coming from the pump coupling. Unusual vibration, and/or noise emanating from the coupling are indications of coupling failure. If the pump drive motor is fitted with a shroud, which is an external cooling fan and cooling fan housing, ensure that the fan shroud is firmly attached, that the fan is not vibrating, and that the grill, fan inlet screen, is not blocked with fragments
· Listen for the sounds of bearing failure. This is typically a metallic rumble or grating sound in the region of the pump barrel, the pump bearing housing, or in the region of the motor bearings
· Listen for sounds of pump cavitation. For horizontal centrifugal pumps or any pump with the pump casing exposed, as opposed to vertical pumps that have their casings submerged in liquid, cavitation is evidenced by a very loud, intense, clattering noise in the region of the pump casing. It sounds like the pump is trying to pump marbles. Typically, severe vibration also accompanies cavitation. Cavitation is caused by excessively low suction pressure, which allows water to explode into vapor bubbles that then collapse on themselves, making the sharp noises
· Lightly touch the pump motor and bearing housing to sense abnormally high temperatures or vibrations that indicate inadequate lubrication and/or bearing failure.
Check pumps in order to avoid unexpected problems
