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Consider variable frequency drive on pumps

I'd be curious also, especially with constant speed motors. Pumps that spend a lot of time on the far left of the curve under varying demands might consider variable frequency drive (VFD).

If you have a fixed demand or process (i.e. the old 80% rule of thumb) power factor correction capacitors can save electricity on a lot of motors or a large motor and cheaper than VFDs.

VFDs not only are suitable to existing electrical nose on a line, they make a lot of noise also with no filtering.

The key trick is what do you have to measure with if there is no recording equipment.

You can get an idea of a pump's performance usually from pressure recording equipment if equipped with a steep curve pump. If not many larger electrical starters may be equipped with amp and volt meter recorders amps=flow. The benefits of VFD control on friction dominated systems are well documented as we as methods to record load indicating transducers. There is a dearth of information about actual operating points in the field.

Fire pumps run weekly to monthly at shutoff with only enough water for thermal relief dumped out to keep the pump from overheating per 2010 NFPA 20, 4.11
HSC and vertical inline electric fire pumps use a pressure relief valve set to dump water at churn like those in the above album. They are 3/4" up to 2500 GPM and 1" past that to 5000 GPM. Electric pumps are always overheating, burning out seal packing, seizing up and occasionally breaking shafts due to improper settings, usually discharge piping problems such as above.

Diesel fire pump engines use water cooled heat exchangers, the water through the pump to supply them is enough to keep the pump cool.

That's "WHEN" fire pumps are run. If you look at the rusty water coming out, they are usually never run. The problem running at shutoff is not just deflection. The heat results in galling and eventually seizure, making it easier to twist the shaft on the motor side of the impeller. In addition, the hot water burns out the seal packing, resulting in additional seizure. Why we use VFD for pumps?

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