Air Receiver Sizing

 

Air Receiver Sizing Formula
\( AR =  p_{atm} \: t \; \left(Q_{out} \;-\; Q_{in} \right)  \;/\; p_i \;-\; p_f  \)
Symbol	English	Metric
\( AR \) = Air Receiver Size	\(gal\)	\(L\)
\( Q_{in} \) = Flow In	\(ft^3 \;/\; sec\)	\(m^3 \;/\; s\)
\( Q_{out} \) = Flow Out	\(ft^3 \;/\; sec\)	\(m^3 \;/\; s\)
\( p_{atm} \) = Atmospheric Pressure	\(lbf \;/\; in^2\)	\(Pa\)
\( p_f \) = Final Pressure	\(lbf \;/\; in^2\)	\(Pa\)
\( p_i \) = Initial Pressure	\(lbf \;/\; in^2\)	\(Pa\)
\( t \) = Time	\(sec\)	\(s\)

Air receiver sizing is the process of determining the appropriate size and capacity of an air receiver tank in a compressed air system.  An air receiver, also called air storage tank or compressed air tank, is a vessel used to store compressed air and maintain a consistent supply to meet the varying demand of a compressed air system.  The sizing of an air receiver is needed for the efficient and reliable operation of a compressed air system.

This calculation uses the air consumption rate of the instruments and determines the size of an air receiver based on the time required to meet a minimum pressure.  The minimum pressure is generally the low pressure set point of a compressor.  The initial pressure is the design pressure the receiver.  The calculation is displayed symbolically as:  If the compressor only runs when the low level pressure is met, then the $flow_in_$ would equal zero.

Key Considerations in Air Receiver Sizing

Compressed Air Demand  -  The size of the air receiver is influenced by the demand for compressed air in the system.  A larger demand may require a larger air receiver to ensure a stable supply of compressed air during peak usage.
Duty Cycle  -  Understanding the duty cycle of the compressed air system is important.  A system with frequent start-stop cycles may benefit from a larger air receiver to help smooth out pressure fluctuations and reduce the number of compressor starts.
Pressure Drop  -  The air receiver should be sized to minimize pressure drop between the compressor and the point of use.  This helps maintain a consistent pressure level throughout the system.
Compressor Size and Type  -  The size and type of the compressor in the system affect the air receiver sizing.  Different compressors have varying characteristics, and the air receiver should be compatible with the compressor's performance.
Safety Regulations  -  Compliance with safety regulations and codes is essential.  Local regulations may dictate minimum standards for air receiver design, construction, and safety features.
Condensate Handling  -  The air receiver should be designed to allow for proper condensate drainage to prevent water accumulation, which can lead to corrosion and other issues.
Temperature and Ambient Conditions  -  Considerations should be made for ambient temperature and environmental conditions, as these factors can impact the efficiency and performance of the compressed air system.
Future Expansion  -  It's often wise to plan for potential future expansions in the compressed air system when sizing the air receiver to avoid the need for frequent modifications.