maximal head
maximal head
(OP)
Can someone please assure me that the no flow point on a head flow diagram for a centrifugal pump correspond indeed to the maximal head ? The reason I ask is because I want to replace HUPA 25-7.0 U 180 with HGPA 25-7.0 U 180. For the both the no flow (maximal head on the diagramm) is 7 m, only the second is 3 times more powerfull and, for instance, if at the head 5m the first produces about 2 m3/h, the second at the same head pumps about 4 m3/h. Is there I am missing something and my more powerfull pump could burst the system (produce the head more than the mentioned 7m), if a valve get closed?





RE: maximal head
RE: maximal head
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: maximal head
Imagine the both pumps to be sucking from an open to atmoshere source into a pipe and then suddenly a valve on the pipe closes. I understand well that the slugs would be very different in the two pipes, but then, the statics on both are indeed 7m ? (although the pumps produce very different thrusts on the liquid) Where is the trick ?
RE: maximal head
Imagine the both pumps are pumping liquid from an open to atmoshere source, each into its pipe. Then, suddenly valves on the pipes closes. I understand well that the slugs would be very different in the two pipes, but then, the statics on both are indeed 7m ? (although the pumps produce very different thrusts on the liquid) Where is the trick ?
RE: maximal head
RE: maximal head
Water hammer is related to the water velocity in the pipe.
Water hammer is usually designed out of the system by controlling the time that it takes a valve to close, lower fluid velocities, etc.
RE: maximal head
RE: maximal head
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: maximal head
RE: maximal head
To obtain optimum pump service life, select a pump that operates close to the BEP.
Most piping systems are rated substantially above 21 m design pressure.
RE: maximal head
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: maximal head
RE: maximal head
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: maximal head
2m3/hr is a bit less than 1m/sec so you should be able to get that through a 50 OD pipe, but with more pressure.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: maximal head
RE: maximal head
therefore using the number supplied by littleinch for ND50 and PPR50 the head loss thru PPR 50 as compared to ND 50 is;
increase in Hl == 55/33^5 = 12.8 times the head loss thru the 50 PPR pipe / ND 50.
There still isn't enough info from yourself to make any major recommendations.
you need to supply head and flow thru the system with the existing pump/s - the change in elevation from inlet to discharge, the performance curve for the existing pump and for the "new" pump - from here we can calculate some operating conditions for both pumps.
Alternately, employ an engineer experienced in pump systems who can sort it out for you.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: maximal head
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: maximal head
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: maximal head
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: maximal head
Head increases ^2 for flow change / same pipe diameter, change of diameter ^5
as a quick and ready proof using a standard Darcy formula friction loss chart
600 GPM 6" Diameter pipe = 2.7 ft Hl/ 100
600 GPM 3" diameter = 75.7 ft Hl /100
(6\3)^5 x 2.8 = 86
Certainly look like d^5 not d^2 to me.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: maximal head
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: maximal head
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)