How many times have you repaired a coupling (or know a technician who repaired a coupling) only to return in a short period of time to repair the same coupling again? Did you or that technician take the time to figure out why the coupling went out in the first place? Sometimes we do but most of the time we are in a hurry and want to get the system fixed and move on to another job. There is an inner desire in all of us to make the customer happy by restoring there hydronic system so comfort or temperature control can be realized once again. Going back to the basics can help us from making that return call to make another repair.
A quick check of the pump maintenance log (if one is kept) would give you a timeline of the last time someone looked at the coupling and checked it for wear and tear. A regular maintenance schedule for a pump should be done at least every 90 days and it should include:
- A check for any unusual noises when pump is operating. The check should include the pump under normal load and heavy load. Possible unusual noises could be pump cavitation (sounds like ball bearings being pumped through the bearing assembly), bearing noise, and other vibration noise that can be transmitted through the piping system.
- A check of the coupling. This should include normal or abnormal wear and tear.
- Pump lubrication – sometimes these are Zirc fittings which need a manufacturers approved grease or it can even be a simple oil cap that needs some 30 weight or machine oil. Always use the pump manufacturers recommendations.
- A check for leaks should be made especially around shaft seals on bearing assemblies. Replace seals and o-rings, tighten assemblies, or change gaskets as necessary.
- The electrical circuit should be checked for tight connections from the disconnect box all the way to the pump pecker-head. If the pump is controlled by a variable frequency drive or variable speed drive this should be checked to make sure it works properly by stepping the pump up and down with the range of operation. Of course before operating any pump there should be an effort to ensure all the valves in the system are open to allow proper flow. HOA or the pumps Hand-Off-Automatic switch should be checked for proper operation including manual and automatic AND the off position.
- Alignment of the pump to the bearing assembly should be checked. Vibration analysis should also be checked to ensure no unusual vibrations are in the system.
- Hardware and safety features should be checked to make sure bolts are tight. This check should also include pipe support near the pump. Pipe support should be adequate enough to prevent the weight of the pipe from straining pump supports. The foundation should be checked to ensure no cracks in the concrete caused by either weight factors or vibration factors from the pump and associated piping.
- Pump capacity needs to be checked from time to time to make sure the impellor is not damaged and has the appropriate capacity to pump the proper amount of liquid through the loop. A proper check can determine if the pump has the ability to pump the proper amount of fluid. It can also determine if the pump is oversized. Oversized pumps offer their own set of problems that need to be addressed. Oversized pumps can be fixed by a variety of methods. Check with your local pump supplier for options.
A good technician also knows that too much maintenance is a waste of time and can cause problems and unnecessarily interrupt service. A good way to estimate the time you need to perform maintenance is to check with the seal and/or bearing manufacturer reference to the MTBF or their estimate of Mean Time Between Failure. This can help you determine the correct maintenance schedule to ensure you get to the problems before they occur. If the MTBF calls for an average failure at 14 months and the system fails in 3 months an assessment needs to made to see what conditions exist to cause the premature failure.
The Department of Energy lists Basic Pump Maintenance as:
- Bearing lubrication and replacement
- Mechanical seal replacement
- Packing tightening and replacement
- Wear ring adjustment or replacement
- Impellor replacement
- Pump/motor alignment
- Motor repair or replacement
Matching the DOE list with my list you will find a correlation to every item referenced on the DOE list except my list goes above and beyond the basic list and this is to ensure no doubt that no stone will be left5 unturned in basic pump maintenance.
Predictive Pump Maintenance
A good facility manager will keep accurate records and set up a program of following issues that arise over a period of time. Doing so one can set up a predictive maintenance program that catches the pump problems before they occur. Of course there are Predictive Maintenance Software programs available to make this easier but only if the maintenance budget can afford the predictive maintenance programs.