Your Essential Guide to Submersible Pump Maintenance
A Best Practice Guide To Maximising Submersible Pump Life
Audex manufactures submersible pumps that last longer, for an energy-efficient, more productive lifetime than standard clean-water pumps generally do. However, like any heavy-duty equipment asset, correct installation and a planned maintenance program is essential to optimise the pump’s working life.
Pump Maintenance Cost Vs Pump Repair Or Replacement
When considering your company’s approach to maintenance, the cost of maintenance needs to be weighed against the cost of pump failure, and also the impact on daily energy costs. Pumps that are operating at their peak will be more cost-effective to run than those with heavily worn parts. Here, we seek to present an overview of best practice advice whilst identifying the most important elements of maintenance. It’s understandable that a pump that is only run now and then might not warrant as much attention as a process-critical pump that needs to continuously run. However, auxiliary or randomly used pumps will still need to be checked and tested at intervals to ensure they have not deteriorated over time.
Where a pumping operation is part of site safety (such as a mine), or critical to high-value output, it’s common to find more than one pump connected to the system to allow for redundancy, known as ‘duty standby’. In these cases, the pumps will run through a periodic cycle; one pump is running, whilst the other is being serviced or held ready to operate.
The Audex, SlurryPro, LSM and Toro pumps we supply are known for longevity and Atlantic Pumps are able to react quickly to service or replace pumps and their parts within a very short time period. Whether you choose to run a more reactive or a fully preventative program for any given pump, planning ahead is vital to prevent excessive downtime and an unexpected spike in costs.
Submersible Pump Maintenance Schedule
Proper pump maintenance can significantly extend the lifetime of your submersible pump. Submersible pumps spend their working life submerged in water, often handling dirty, aggregate and sand-laden slurries - so regular inspections, oil changes and replacement of worn parts are very important.
The recommended weekly, monthly and annual maintenance tasks will depend on a few factors; mainly the working conditions, and the pump model. Check your pump’s operating manual, but generally you’ll want to consider inspecting following on a regular basis:
- Check for strange sounds or vibrations when the pump is in operation.
- Check flow/pressure at the discharge end.
- Check for leaks from pipes and valves.
- Check the power drawn from each phase by clipping a CT ammeter around the cable. If the reading has changed significantly since the pump was installed, or if one phase has a notably higher or lower current than any of the other phases, stop the pump and call the distributor/manufacturer for advice.
- Check for heat coming from any wires or switches. An infrared thermometer allows for safer, non-contact heat detection.
- Check that the float switch or alternative level sensor, where fitted, turns the motor off when the pump is raised out of the water.
- Check the oil level is correct. Extract a small amount by tilting the pump until the oil plug faces downwards. If the oil is discoloured, or mixed with water, then it’s likely that the seals will need replacing before the pump is next run.
- Check the strainer is not fouled or damaged.
In addition to the monthly routine checks, at least once a year your pump will need:
- An oil change. Clean oil is essential for any pump, providing lubrication for rapidly rotating parts. Remove the oil plug and drain the oil completely (by positioning the pump with the plug at the lowest level). Once drained, turn the pump over and pour the specified oil type and volume (see pump manual) into the oil chamber inlet. Audex recommends biodegradable hydraulic oil. Dispose of the drained oil in compliance with all local/ regional laws. Replace the O-ring seal onto the filter plug, and screw the filter plug back into the pump. Wipe up any excess oil so that any leaks can be quickly spotted.
- Check the strainer and inlet to the volute. First, isolate and lock-out the pump from its power source, and ensure that there is no pressure in the system. Caution: wear and damage can cause sharp edges to form across metal parts. Remove the strainer and bottom plate (if fitted) and check these for damage or wear. Compare the size of the holes in the strainer to the pump’s original specification; if these wear enough they could allow larger solids into the pump than it is designed for. A feeler gauge or micrometer is good for measuring wear over time.
- You should now be able to turn the impeller by hand to get a feel for bearing and shaft wear. If there is play or looseness in the shaft movement, or a bumpy rotation, then further dismantling and parts replacement are likely needed. In this case refer to the pump manufacturer or supplier for assistance.
- Inspection of the impeller and volute. If the shaft and its bearings are OK, the next wear part to check is the impeller. Remove the set screws and machined strainer studs, and release the wear plate and corresponding shims. Next, remove the shaft cap nut and impeller retaining nut, along with the impeller boss cap. Now you should be able to remove the impeller, either by pulling directly by (gloved) hand, or with mechanical aids. Do not under any circumstances apply heat to the impeller.
- Inspect the condition of the inside and outside of the impeller and the volute surface. Worn surfaces and edges degrade pump efficiency and performance, and if ignored, shorten the time to failure.
- To fit or refit a good impeller, push it onto the shaft with an aluminium or copper-based anti-seize. Do not use heat. Ensure that the impeller is on the correct way round; The impeller’s closed side is towards the motor, with the vanes facing the intake.
- Insert the impeller boss cap, spring washer, impeller retaining nut, and the shaft cap nut.
- Place the wear plate shims onto the wear plate and place into the volute, fastening with the set screws equally spaced (using every other tapped hole if there are more holes than screws).
- Insert the machined strainer studs.
- Place the strainer onto the pump (and the bottom plate where present) and secure it with the washers and nuts.
Servicing, Refurb And Repair Of Submersible Pumps
Submersibles are a complex type of pump, as they have to be sealed against water leakage into the motor, even at the greater pressure of water at down to 30m depth. For many duties, they more than compensate for the extra engineering involved through greater energy efficiency and ease of operational use.
If you are having problems with your submersible pump, check out this detailed troubleshooting guide from Audex.
Due to the aforementioned complexity of how a submersible works, full pump servicing and repair work often has to be carried out in a dedicated workshop. Such pump repair centres have the necessary equipment to change bearings and do other specialist pump refurbishments.
Pump Wear Parts That You Should Expect To Replace On A Periodic Basis.
Seals are essential to preventing leakage into the pump’s motor and electrical parts, Audex submersible pumps use precision-made mechanical seals for long-lasting performance. Due to the importance of shaft seals on electric submersible pumps, it is recommended that seals are fitted with an early warning or cut-off device to prevent damage and electrical shock.
Even without cavitation, impellers in pumps that handle abrasive fluids, such as water containing silt, the impeller will wear down over time. As the impeller wears, pump efficiency is degraded so be prepared to replace these periodically to save energy costs.
Again, a pump shaft can wear down from contact with abrasive particles in the fluid, albeit not so much as the impeller. The fast-spinning shaft is apt to damage from lack of lubrication, shock damage from large solids or blockage events and heat-friction should the submersible be run dry.
Wear plates are designed to deflect solids away from the pump’s inlet edges, taking the brunt off the pump’s body to protect it from expensive to repair damage.
Wear rings provide the interface between stationery and rotating pump parts. The material used for these sacrificial wear parts is designed to be softer than the pump’s main material.
O-rings are vital to keep the pump’s rotating parts and seals in place. Inexpensive to replace, so are usually changed at every service or inspection to keep the pump balanced.
Important in any pump but critical to submersible pump llifetime, gaskets provide a stationary water-seal between the pump’s case sections.
Oils, oil filters and lubricants
Lubricating oil needs to be kept clean and topped up to prolong submersible pump life.
Diesel pumps require their own set of parts for the engine, as such they usually require more maintenance than their electric counter-parts.
- Air filters
- Oil filters
- Hydraulic filters
- Fuel filters
- Fuel injectors
- Hydraulic fluid
- Transmission fluid
- Engine oil
- Engine starters
- Spark plugs
Lastly, when considering supplies and stocks of submersible pump spare parts, don’t forget the pipework, valves and gauges that make up the pumping system!
Atlantic Pumps are a fast-response manufacturer, supplier and repairer of large-scale industrial submersible pumps. Their Audex pumps keep operations going in heavy industries such as mining and quarrying, construction material production, recycling and factories handling some of the most challengingly abrasive fluids.
Audex submersible pumps and parts are backed up globally through the Intrax Group. For UK and EU service, contact Atlantic Pumps.