For some reason I find 2.31 ft/psi easier to remember and either multiply
or divide by that. Either way, from waist high on 1st floor to waist
high on 2nd floor is only about 3 or 4 psi static pressure difference
(unless the neighbor has very tall ceilings).
If 2nd floor flowing pressure seems much lower, it could be a restriction
like debris in a faucet aerator or mineral deposits (especially in
David Efflandt - All spam ignored http://www.de-srv.com /
To clarify that: The RELATIVE pressure goes up
by about 1/2 psi per foot, reguardless of whether the system
is opened or closed. Since the OP wanted to calculated
pressure on one floor, by reading a guage on another, this
is sufficient. What depends on an open system is
figuring the ABSOLUTE pressure, which in an open system
near sea-level will be 1/2 psi / foot, plus atmospheric
pressure at the top of the water column.
As a general rule (if you don't need to be exact) you can assume a 5psi loss
per floor above ground level, or .5 psi per foot. This is the way fire
engineers and fire protection system installers generally figure pressure
loss due to elevation.
This has been rattling around for quite a while. The static loss (no
water flowing) is easily found. A cubic foot of water weighs 62.4 lbs.
A square foot is 144 sq. inches. The pressure from 1 foot of water is
62.4 lbs divided by 144 sq. inches or 0.433 lbs/sq inch. Ten feet of
elevation looses you 4.33 lbs/sq in of pressure.
The real issue though is how much is lost due to "friction" or drag as
water moves through pipes and around corners and bends in the plumbing.
One needs to know the diameter of the pipe, how many bends and the
extent of those bends (30 degree, 45 degreee, or 90 degree,) the length
of the straight bends, and the flow rate. Once all of that is known you
can calculate the pressure at the outlet end.
But aside from "The White House" could diameter of pipe, bends, length of
straight runs possibly be a significant factor in a single family residence
when merely attempting to calculate the drop in pressure at the 2nd floor of
a two story house?
There is but more info is needed. The basic formula is Q=AV where Q is the
flow rate, A= the area of the pipe, V= the velocity. Velocity can be
derived from the formula Delta P=V^2/2g or V^2=2g(delta P). Then: Q=A* sq
root (2g*delta P). Then there is the constants to assure all the proper
units. Then there is the much easier way and that is to go to any hydraulic
text or Hydraulics Handbook (like Crane's) that gives you all the formulas
without doing any work. Go into Google with *pressure drop*
Well, gentlemen.... I now know everything I ever wanted to know about the
difference in static water pressure as a function of height in a domestic
I COULD measure it a mic, mark it with a chalk... but we're just gettin' set
ta' cut it with an ax so... 1/2 #psi/foot of elevation will surely suffice.
By the way. I'm curious that Irish Math, Joe; "26 + 6 = 1 It's Irish Math".
I'll bite. What's the riddle?
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.