3 replies to this topic

[Propacket]

Many of our expert friends might have sized the compressed instrument air reciever which store the air at pressure of 80 to 140 psig.: I m looking at formula for sizing the reciever like in the below link.

http://www.piping-de...ing_Calculation

if you have noticed that input in the formula is standard flow of air. So i understand that volume of the reciever will also be standard volume and we should convert this standard volume to actual volume at actual conditions that is at 80 psig.

Any comments?

[ankur2061]

For any containment equipment whether it be vessel, tank, pipe the volume occupied is defined at some standard conditions for compressible fluids in engineering terminology.  This is because compressible fluid volume is a function of both the pressure and temperature. Pressure and temperature being highly sensitive variables it becomes inconvenient to define stored volume at actual operating pressure and temperature. Defining stored volume of compressible fluids at standard conditions is easy and convenient because the standard pressure and temperature values are defined and not variable.

 

Based on what I have explained above it is convenient to define air volume stored in an air receiver at standard conditions such as Nm3 where N indicates volume at standard conditions of 101.325 kPa (abs) and 0°C. However, please note volume of air receiver in datasheets or specification is defined based on the geometry (length and diameter) of the air receiver which can be considered at a defined standard condition..

 

In other words, for a containment equipment of fixed geometry, the volume is fixed and the mass of the compressible fluid stored in the containment equipment varies depending on the pressure and temperature of the compressible fluid.

 

Hope this helps.

 

Regards,

Ankur.

[Propacket]

Thanks Mr.Ankur.
Sir I can understand what you have explained above.
Actually my problem is that I want to size an air reciver for 30 mins standby time for peak consumption of 100SCFM with pressure change from 150 to 100 psi. So when we put above figures in the receiver sizing formula as given in the above link it gives reciever capacity of 1120 ft3. I understand that this is volume of free air not vessel volume. Air volume must be converted to actual conditions before we use it to size the vessel.Looking for your comments.

[Bobby Strain]

Try simple arithmetic. You will get about the same answer as you indicated.

 

Bobby