Run Time Calculations - RFS APD-D Series Product Manual

11 RUN TIME CALCULATIONS
The following calculation can be used to estimate the amount of run time an APD-D series dehydrator will
take to pressurize a given volume. This calculation is a simplified best-fit estimate. Actual pump times
will be dependent on many variables, such as:
 APD-D flow variations. Each dehydrator has flow variations. The specifications indicate the
minimum flow for each model.
 APD-D service condition. How old the unit is, how well maintained.
 APD-D environmental conditions. The environment in which the dehydrator is operating
has an effect on its performance.
 System flow restrictions. Any restrictions in the distribution system which the dehydrator
is pressurizing can have pronounced performance consequences.
 System air tightness. Any leaks in the distribution system which the dehydrator is
pressurizing can have pronounced performance consequences.
 And other variables...
−
.
=
−
=
= Total system run time in minutes
= Volume of system in m
= Volume conversion factor to cubic feet
= 35.314 for Volume in cubic meters (m
= 1.0 for Volume in cubic feet (ft
= 0.1337 for Volume in gallons
= 0.0353 for Volume in liters
= Lower operational pressure, psig (where
compressor starts)
= Upper operational pressure, psig (where
compressor stops)
= Effective flow (linearized average)
= Dehydrator output flow, CFM (cubic feet per
minute @ MSL, 0 psig, 23° Celsius, 50%RH)
= 0.22 for APD20-D
= 0.19 for APD22-D
= 1.0 for APD70-D
= 0.85 for APD72-D
= Flow correction factor for pressures above
0 psig
= 0.91 for APD20-D, APD22-D, APD72-D
= 0.92 for APD70-D
= Elevation AMSL (above mean sea level) in
feet
Page 22 of 24
+ −
, ft , gallons, or liters
3 3
3
)
3
= Elevation correction factor for flow
= 0.000024 for APD20-D
= 0.000022 for APD22-D
= 0.000070 for APD70-D
= 0.000060 for APD72-D
= Pressure correction factor for elevation
= 0.94
)
Excel Formulas:
Assume APD20-D with
33 meters of E65 elliptical
waveguide.
calculated in cell A10:
=((A5*A6^A4-A7*A8*A9^A4)+(A5*A6^A3-A7*A8*A9^A3))/2
calculated in cell A11 in fractional minutes:
=A2*A1*((A4-A3)/14.696)/A10
calculated in cell A12 in [h:mm:ss] format.
=INT(A11/60)&":"&TEXT(INT(MOD(A11,60)),"00")&":"&TEXT(
INT(MOD(A11*60,60)),"00")
602400011500
Revision C