hydrant flow tests
hydrant flow tests
(OP)
i'm working on water model calibration for a small municipal water system. because the largest demands are typically fire related, calibration requires that we use hydrant flow tests to stress the system. my first question is just about fire hydrant flow tests in general.
hydrant flow tests are generally conducted with a pitot gauge held in the water stream. this pressure (or velocity head) is converted to a flow by means of a chart or equation which is bascially a form of the small orifice equation. the smoothness of the hydrant outlet is a factor in this calculation.
my question is, for a multiple outlet fire hydrant, wouldn't using a pressure gauge on the other outlet give you a pressure without the use of a pitot gauge. furthermore, wouldn't this negate the need to worry about the friction losses related to outlet smoothness in calculating the hydrant flow?
thanks.
hydrant flow tests are generally conducted with a pitot gauge held in the water stream. this pressure (or velocity head) is converted to a flow by means of a chart or equation which is bascially a form of the small orifice equation. the smoothness of the hydrant outlet is a factor in this calculation.
my question is, for a multiple outlet fire hydrant, wouldn't using a pressure gauge on the other outlet give you a pressure without the use of a pitot gauge. furthermore, wouldn't this negate the need to worry about the friction losses related to outlet smoothness in calculating the hydrant flow?
thanks.





RE: hydrant flow tests
The friction losses are a necessary variable in the velocity head portion of the flow equation. During Static Pressure, friction losses are, of course, zero.
Engineering is the practice of the art of science - Steve
RE: hydrant flow tests
RE: hydrant flow tests
I have always been meaning to do the test in that manner and test with a pitot to compare.
You could also reference NFPA 291 for more standards on fire hydrant flow testing.
RE: hydrant flow tests
In particular flow testing:
http://firehydrant.org/info/ftest1.html