Tips For Restarting Centrifugal Pumps (And Others) After Long Shutdowns

Shutdowns for unplanned issues or even planned maintenance can put a dent in your operations. It's likely that you will need to inspect your equipment after a shutdown to ensure everything is running smoothly. 

Before diving into these steps, remember to check your parts kit inventory. As pumps are prepped for restart, it’s highly possible maintenance teams will find parts that need replacing, or a pump could fail during start-up. Check to make sure you have enough parts on hand to complete work during inspections.

Positive Displacement and Centrifugal Pumps

After long periods of shut down, it is essential the proper attention be given to pumping equipment to continue providing reliable fluid transfer. Following these steps will ensure a problem-free restart.

Check that the pump spins freely

According to Crane’s Service Manager, the most important thing to check first on positive displacement and centrifugal pumps is that the pump still spins freely. It’s possible the pump could contain solidified product or have mechanical issues from sitting idle.

To check this, lockout the pump, remove the coupling guard and turn the shaft. Listen for rubbing sounds. Most centrifugal pumps should turn by hand. If the pump doesn’t turn, don’t force it. Instead, take it apart and inspect.

On large pumps or positive displacement pumps, the shaft may be difficult to spin. Do not use a pipe wrench to assist. Using a pipe wrench will damage the shaft and could cause additional damage to other components. A strap wrench will suffice if necessary on a large centrifugal pump or positive displacement pump.

Check coupling condition

Since the coupling guard is off, now is a good time to check the condition of the coupling. Look for evidence of wear. This could include rubber dust or plastic chunks under the coupling. This is evidence of misalignment; the pump should be re-aligned before re-starting.

Check Mechanical Seal

Inspect the mechanical seal for leakage. If there is flush water to the mechanical seal, make sure it’s turned on.

Check oil and lubrication levels

All pumps and drivers (electric motors, turbines, gears, etc.) must be properly lubricated. Check the IOM for proper lubrication tips for each specific pump.

Valves In Correct Position for Start-Up

Ensure suction valves are open and liquid is at the pump. Discharge valves should be 10-15% of full open.

Ensure pump is primed and vented

Now that the suction valve is open, liquid should fill the pump and prime it.

Inspect Base

Now that the pump is almost ready, do a final check of the base to ensure that mounting bolts are tight. There should be no soft feet on the pump or motor.

Baseplate pads should be level to within .002” per foot and the maximum out of level from one end to the other should not exceed 1/32”.

Start-Up and Final Check

After the pumps are started, verify that they run smoothly with no unusual noise, vibration, or overheating of bearings.

Air-Operated Diaphragm Pumps

Air-operated diaphragm pumps require attention to both the pump itself as well as the air system.

1. Blow out air lines - Condensation can form in airlines causing rust and debris to be blown into the air valve and pilot valve.
2. Change inline filter element - If not changed recently, filter elements may become dried and clogged robbing the pumps of required PSI and SCFM.
3. Ensure pump is primed - Running an AODD pump dry will quickly destroy diaphragms.
4. Discharge valve is open
5. Flush the pump - Solids may have settled in the chambers potentially causing damage during restart to shafts and diaphragms. If flushing is not an option, start the pump at low pressure to agitate fluid and solids within chambers. Do not flush with pressurized water or steam.
6. Check your stock - In the case of failure, it is critical to have the necessary parts and kits on the shelf to reduce process downtime.

Taking the time to prep pumping equipment before start-up ensures the pumps are ready, and you are too! 

Need help getting pumps back after a shutdown? Ask us about it! We provide start-up services to businesses and municipalities in Wisconsin, Minnesota, Iowa, and upper Michigan.