To
convert inches to millimeters:
_____inches x 25.40 = _____mm
To
convert millimeters to inches:
_____mm x .0394 = _____inches
Pressure
at High Altitudes
Pressure
and vacuum ratings are good for sea level (14.7 psi atm. press.)
only. This chart may be used to determine pressure developed
at altitudes above sea level. For example, a 5 lb. machine
produces 5 psi at sea level. At 5000' elevation, the same
machine produces only 4.160 psi.
The
following table was derived by using the head formula.
*Variations
in pressure with changes in altitude are directly proportional
to the relative density of the air.
The
following can be used to compute atmospheric pressure at the
altitudes indicated according to the relationship:
Blowers
are rated at standard air: .075 lbs./cubic ft.; 70F at sea
level; therefore, pressures corrected to standard conditions
must be used when selecting Blowers from rating tables Listed
below are the factors to convert to standard conditions
or curves. Caution: size motor for highest density (lowest
temperature and lowest factor) condition at which it is
expected to operate.
The
following table was derived by using the head formula.
*Variations
in pressure with changes in altitude are directly proportional
to the relative density of the air.
HP1
= HP2 x factor where HP1
= horsepower at standard conditions
HP2 = horsepower at operating conditions
P1 = P2 x factor
where P1 = pressure at standard conditions
P2 = pressure at operating conditions
This
chart may be used to compute friction losses in a piping system.
For example, determine the friction loss incurred when 70
CFM flows through a 2" pipe, 50' long.
Step
1: Intersect 70 CFM and the sloping line for 2" pipe
as shown. Step 2: Drop a vertical from this point of inter section
and read the loss/100' of line, in this case, .60 Hg/100'. Step 3: Multiply the loss/100' of line by the length
of run/100'.
The
following can be used to compute atmospheric pressure at the
altitudes indicated according to the relationship:
