First off, I'm an IT guy and not an engineer. I've been tasked with figuring out and monitoring the efficiency of some pumps. Thing is, I don't have a lot of data to work with. I don't know the total head for any of the pumps. One or maybe two have a voltmeter. Heck, I don't even know the size of the wells they are pumping from. About the only data I know I have for certain is:
- Pump Start/Stop times
- Pump Start/Stop set points
- Water level
So I need help with the logic here, not the math.
I know I'm not going to be able to calculate the hydraulic efficiency because I don't know the model of the pumps being used let alone things like impeller sizes or shaft rotational speeds. But I think I can calculate a quasi volumetric efficiency. For that, I only need to know how much stuff gets moved in a certain period of time. Then I compare today's flow rate to yesterday's flow rate to determine if it is more or less efficient than it was yesterday/last week/last month under the assumption that the only thing that is changing is wear and tear on the pump.
Since the pumps don't move, any efficiency lost due to working against pressure/gravity/head should be roughly the same as they were yesterday so I can effectively ignore that, right? And the size of the well isn't changing so I can just as easily say it is 1. Unit doesn't really matter since I am comparing it to yesterday's calculation. It could be 1 cubic meter, 1 gallon, 1 swimming pool. The unit of measure (UOM) is only useful for comparing it to other calculations in other systems. Here I'm just comparing this pump's flow rate with its flow rate yesterday, so the UOM could be 1 Tim for all we care.
So my thought is to calculate the fill time of the well by looking at the elapsed time between the pump stopping and starting, and calculate the draw down time of the pump by looking at the time that lapsed between the pump starting and stopping. I know I need the fill time because the well will be filling while the pump is pumping. That means it not only pumped out "1 Tim" of water, it also pumped out a little more. This will give me the "Tim's per minute". If I compare today's number with yesterday's number, that should tell me if a pump is starting to fail, no? Even if the pump starts to fail mechanically, I would see this in my calculation because it would take longer to pump the same amount as it pumped yesterday.
Does this seem like relatively solid logic? Is there a way I can get a better efficiency calculation with the very limited information I have available? (The pumps are at various farms and travelling to them is not really feasible, nor is there any kind of budget to add meters or additional equipment.)