MiLKy
,
Sunday, 8th of August 2010 01:26:28 PM
There is a figure for the amount of metres rise (head ) to a lower outlet
MiLKy
such as a tap or shower,but l cannot seem to find it.
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Cakey
,
Tuesday, 10th of August 2010 11:50:58 AM
Rule of thumb = For every 1 foot of head, the pressure at it`s
Cakey
base will be half a pound per square inch. In other words if the waters
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surface in the header tank is 8 feet above the tap then the static
Joined: Sunday, 25th of April 2010, 10:11:22
pressure at the tap will be roughly 4 pounds per square inch.
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beemac
,
Wednesday, 11th of August 2010 08:12:15 AM
If there is a header tank the head is taken to be the
beemac
difference in height between the water level in the header tank & the
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point ur are looking at (here the shower/tap outlet)
Joined: Wednesday, 12th of May 2010, 10:24:11
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If there is no header tank (direct cold water), then the head is the
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difference between the height to which the cold water could be pushed, &
the height to which it is being pushed.
p=rho*g*h
where
p is the pressure due to the difference in water heights in Pa (or N/m^2)
rho is the density of the water, about 1000 kg/m^3
g is gravitational field strength, 9.81 N/kg
h is the head in m
If you have a booster pump you will usually need some head (.5m minimum?),
so that a flow switch can detect a flow when a tap is opened, & then turn
the pump on (it also help prevents damage to the pump through cavitation).
Another arrangement is to have a pressure switch in the pipes, which will
run the booster pump, when the pressure in the pipes is lower than a set
value (open the tap- the pressure in the pipe to the tap falls, so the
pump turns on. Shut the tap- the pump runs until the pressure in the pipe
to the tap exceeds a set value)
Fittings, & long pipe runs reduce the dynamic head (due to
friction/turbulence when the fluid is moving). Static head doesn't take
this into account
Satou
,
Thursday, 12th of August 2010 05:37:40 PM
The head is just the vertical distance from the top of the
Satou
water level in the tank to the outlet.
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