Pressure gauge range 3

[corden]

Hi Experts,

If I have a pressure gauge on a discharge pump and it has an operating pressure of 7 kpa-g and max operating pressure is 26 kpa-g, what is the best measurement range that I will use?
If the design pressure is 1770 kpa-g do I still need to cover the design pressure?
Thank you very much for your help!!

 

[zdas04]

This is an operational decision, not a design decision. For some (probably good) reason, the system was designed for 1770 kPa(g). That doesn't mean the gauge will ever see that much pressure and doesn't obligate you to put in a gage that has a range that will make it unusable.

There are two important considerations in selecting gauges: (1) uncertainty is based on full-range, so the bigger the range the greater the uncertainty (in real-world units); and (2) gauges in the lower 10% of range are very difficult to read. So if you pick a 0-1800 kPa(g) gauge with +/-2% uncertainty then every reading will be +/-36 kPa(g) which means you'll never have a reading that means anything at all. On the other hand if you get a 0-30 kPa(g) gauge then your readings will be +/-0.6 kPa which is probably useful.

On the second point, a 0-30 kPa(g) would be in the lower 1/4 of the range all the time which is not terrible, but not great either. I would probably look at a 0-20 kPa(g) gauge and accept that in max operating conditions the gauge is out of range high. That would put normal near the middle of the range.

David

 

[roydm]

7 kPa, that seems very low for a pump, have you included the suction head?
I would be specify a gauge that's at least capable of reading the dead head pressure and I always put a damped gauge on a pump. A gauge on a pump is really not that important, many of our clients don't bother with them.

Compared to the operating pressure the design is very high, the gauge doesn't have to be ranged for that but it should withstand it without bursting, (proof pressure) it doesn't matter if it's destroyed