Compressed Air System Sizing Assumptions
The compressed air system sizing calculator provides a quick, general estimate of the air usage for one or more pumps. Please consult an engineer or other compressed air professional for the site-specific needs of your project.
The air usage calculator is based on the following conditions:
1. The required air pressure for air displacement pumps such as the AutoPump® (Patent Pending) is NOT affected by pump submergence, because the inlet check valve isolates the pump chamber from the well during the discharge cycle. Greater submergence does affect the pump flow rate because it allows the pump to refill faster.
2. 100 psi supply air pressure and a liquid level of 10 ft. submergence over the top of the pump; for other conditions, contact QED or see the “Pump Specifications” section of the appropriate manual in the Equipment Manuals section of the website.
3. Multiple pump air usage is based on all pumps operating under identical conditions.
4. Desiccant air dryers are advised for most systems to ensure a longer and more reliable operating life for all components in the air system, especially under freezing conditions. Although the AutoPumps themselves are designed to handle liquids in the air supply system, condensation water is very corrosive and can attack common components such as any metal piping, filter-regulators and fittings. In the calculator, desiccant air dryers add 15% to the required air flow, in order to support the cyclic moisture venting from these systems.
5. Piston, or reciprocating, compressors are generally designed for no more than a 50% on-time, so the compressor air flow sizing for this type is multiplied by 2X after inclusion of the air dryer’s air consumption. Consult with your compressed air system supplier for the appropriate air receiver tank sizing to ensure that the compressor does not exceed its “Starts per hour” specification. Note that for many applications, rotary screw compressors are considered more efficient and economical for sizes over 5-10 HP.
6. Rotary screw compressors are designed for essentially continuous duty cycle, so the calculator’s compressor air flow sizing for this type adds 10% as a safety factor after inclusion of the air dryer’s air consumption. Consult with your compressed air system supplier for the appropriate air receiver tank sizing.
7. The air usage calculator does not take into account any pressure losses due to friction in the air distribution piping system.