Compressed air is used to operate pneumatic systems within a facility, and it can be separated into three categories; the supply side, the demand side, and the distribution system.  The supply side will include the air compressor, after-cooler, dryer, and receiver tank.  It produces and treats the compressed air before it travels into the distribution system.  They are generally located in a compressor room somewhere in the corner of the plant.  In this blog, I would like to cover the wet receiver tank that is used as part of the supply side.

What is a receiver tank?  I like to compare pneumatic systems to electrical systems.  The receiver tanks store the pneumatic energy produced by an air compressor like a capacitor stores electrical energy.  The reason for this is to have a ready source of energy to increase efficiency and speed through the ebbs and flows of demand. 

A wet receiver, like the name imparts, is positioned downstream of the air compressor but before the air dryer.  A dry receiver would be located after the air dryer.  Some systems will utilize both types.  With the wet receiver, you remove some of the load of water that reaches the air dryer, which helps to make the air dryers more efficient and extends the life cycle.  When ambient air is compressed, the humidity will condense, making water.  Also, as air cools in the wet receiver, water vapor turns into liquid condensate—often mixed with traces of oil and dirt from the air compressor. To get rid of the contaminants, a condensate drain will be required to get rid of this unwanted liquid.

For sizing the wet receiver, it is roughly 1 to 3 gallons per cfm for a compressor.  So, for a 100 SCFM air compressor, you should have a tank that is roughly 100 to 300 gallons.  If you have large fluctuations on the demand side, you can also use Equation 1 below to calculate the minimum tank volume.  If you are using wet and dry receiver tanks in your system, you can divide the total volume.  The wet receiver tank should be one-third of the volume, and the dry receiver tank should be two-thirds of the volume. 

Equation 1:

V = T * C * (Pa) / (P1-P2)

Where:

V – Volume of receiver tank (cubic feet)

T – Time interval between pressure limits (minutes)

C – Air demand for system (cubic feet per minute)

Pa – Absolute atmospheric pressure (PSIA)

P1 – Upper Pressure limit (PSIG)

P2 – Lower Pressure limit (PSIG)

Compressed air systems are the backbone of countless industries and operations.  But behind the scenes, components like the wet receiver and condensate drain play pivotal roles in ensuring these systems deliver clean, reliable air.  If you wish to discuss more ways to optimize your compressed air system, EXAIR has Application Engineers that would like to help you. 

John Ball
Application Engineer
Email: johnball@exair.com
Twitter: @EXAIR_jb