(10008) Whether you are developing plans for an existing installation or a new facility you will need to understand the compressed air requirement when installing pneumatic scissor lift tables. Many of the Herkules customers complete a comprehensive review of compressed air needs at peak time and off peak times. This information provides the industrial engineers with the knowledge to source the correct size air compressors for the job.
Below are the details of how Herkules Equipment Corporation calculates cubic feet per
minute (CFM) and standard cubic feet per minute (SCFM) for our pneumatic scissor lift tables. CFM and SCFM can be calculated based on a variety of standards. We believe the below calculations work best in most cases.
Given:
Volume: 4.7 ft3 Lift table is full up
Pressure: 50 psi Lift table is full up and maximum load
Atmospheric pressure (ATM): 14.7 Constant
Cycles / minute: 0.0167 Calculated below
Terms:
ATM: Atmospheric pressure:
CFM: Cubic Feet per Minute
SCFM: Standard Cubic Feet per Minute
Formulas:
1 TRUE pressure (psia) = Pressure + ATM
2 Actual Pressure (ft3 TRUE) = (Volume * True psi) / ATM
3 CFM max. = (ft3 TRUE) / minutes
4 SCFM = (Pressure * Volume * cycles/minute) / Raise time
Calculations:
Cycle Sequence
Air consumption units are per minute: Inputs
a. Speed for full raised: 20 Seconds = 0.3333 Minutes
b. Lift sets ideal at full raised for: 3600 Seconds = 60.000 Minutes
c. Number of cycles per minute: 1 Cycles per hour/60 minutes = 0.0167 cycles / minute
TRUE pressure:
TRUE pressure = 50 psi + 14.7 psi
= 64.7 psia
Actual pressure:
Actual Pressure = (4.7 ft3 X 64.7 psia) / 14.7 psi
= 20.69 ft3 TRUE
Cubic Feet Per Minute Maximum:
CFM max. = (20.69 ft3 TRUE) / .333 minutes
= 62.06
Standard Cubic Feet Per Minute:
SCFM = (20.69 ft3 TRUE X 0.01667 cycles / minute) / 0.33 minutes
= 1.04