SURGE CALCULATION
SURGE CALCULATION
(OP)
Hi guys,
i need explation on surge calculation in pipeline hydraulics.
what it is all about, why do we have to do it, how to go about e.t.c.
i will appreciate a very simplistic explanation.
cheers
i need explation on surge calculation in pipeline hydraulics.
what it is all about, why do we have to do it, how to go about e.t.c.
i will appreciate a very simplistic explanation.
cheers
Buchi





RE: SURGE CALCULATION
Why do you have to calculate: Because the surge pressure might exceed your design specs incl margins. But you dont _have_ to calculate anything. You may just hope that you have left the company if something goes wrong!
A good simulation might tell you where to spend your money (more steel, surge relief valve, RV's whatever)
You can calculate the total kinetic energy in the volume of liquid moving in the pipeline. If you assume instant closure and no compressability then you should be able to calculate the resulting force easily.
However all liquid _can_ be compressed. This means a (much) lower surge pressure.
From Perry you get the most common "rule of thumb":
h(wh)=a*DV/gc
where
a=sqrt(1/(den/gc*(1/K+D/b*E)))
(velocity of wave propagation)
and
h(wh)= water hammer head
V=change in fluid velocity
gc: grav. constant
den: Fluid density
K: Bulk modulus
D= pipe inside diameter
b: Pipe wall thickness
E: Young modulus for pipe material
Some of these properties might be difficult to obtain
The formula is a conservative estimate of max. surge pressure.
Anyway its complicated stuff. I recommend that you contact a consultant if its critical work and your company dosnt have any inhouse knowledge
Best Regards
Morten
RE: SURGE CALCULATION
Alternatively, you can use "Google" as your search engine and type "Water hammer" and you would get a few sites which would offer a method to do the calculation.
RE: SURGE CALCULATION
RE: SURGE CALCULATION
Thanks!
Pete
P. J. (Pete) Chandler, PE
Principal Engineer
Mechanical, Piping, Thermal, Hydraulics
Processes Unlimited International, Inc.
Bakersfield, California USA
pjchandl@prou.com
RE: SURGE CALCULATION
I have come across the simplified equation,based on (Pipelines Rules of Thumb) by Gulf Publishing 1978:
P= 0.8 x W x V
Where P surge pressure psi
W Fluid density lb/cu.ft
V Velocity change ft/sec
This equation gives < 5% deviation from the standard equation
Try it..
Whylie