As pumpking also mentioned, the minimum flow normally ranges from 10% for small pumps to 35% for the large ones. If 34 m3/hr is 40% of rated flow, 21m3/hr would be around 24% which looks more common for the minimum flow. anyhow ask the manufacturer for clarification (and plz reflect the answer...
Electric motors have their best efficiency point in the range of 60-80% of rated load and smaller ones near 75% of rated power. so selecting a motor which at 75% power fitts (or approaches) the pump rated power is a good suggestion. an electric motor shall not be operated bellow 50% load for...
since the pump C is located at the end of line, you may also check if something has not blocked its discharge pipe or tee (or the main header before pump B)leading to higher pressure drop and head.
Do you have any record of pump powers before re-impllering?
Reza
efficiency=(H x Q x Specific Gravity) / (3960 x BHp)
units:ft, gpm, Hp
You should measure the flow rate, and the BHp at this flow (by measuring the amper)and specific gravity of pumped fluid and then simply use above equation.
Reza
According to PEDARRIN2's interpretation, the pump will turn off more quickly. But the number of pump starts will remain the same during the life cycle of the system. So the total working duration of the pump will decrease.
Hence if the new pump working duration in each start/stop cycle would not...
I guessed that you are talking about CFD transient calculations. If so, this is very hard to answer since CFD calculation results and their accuracy depends on a lot of parameters such as the complexity of your model geometry, the flow charachteristics (i.e. laminar or turbulent, one or more...
Maybe one other point to consider is the position of the isolation valve when starting your pump. Actually it depends on the impeller type and on BHP curve of the pump. If the BHP curve is increasing after shutoff point, you should start the pump with closed valve to demand less electric power...
There are lots of such information on the web which you
can find using search engines, here is some sites containing pump related articles:
http://www.fluidedesign.com
http://www.johnston-pump.com/Miscellaneous/ViewGenericDocuments.asp?GroupID=17&CompanyID=2...
ASME VIII Div II, 4.112 (f) states that Membrane Stress is a component of Normal Stress; While. FIG. 4-130.1 (Note 1) asserts “the symbols Pm, PL, Pb, Q, and F do not represent single quantities, but rather sets of six quantities representing the six stress components”
How could we explain this...
