How to Calculate CFM for Air Cleaning 16 Tubes with 116 PSI?

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Discussion Overview

The discussion revolves around calculating the cubic feet per minute (CFM) required for an air compressor to clean 16 tubes using a system operating at 116 PSI. Participants explore various methods and considerations for determining the necessary air flow rate, including the volume of the tubes and the timing of air releases.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks help to calculate the CFM needed for an air compressor connected to 16 tubes with specific nozzle dimensions and release rates.
  • Another participant suggests a step-by-step method for calculating the required flow rate, including volume calculations and conversions to standard conditions.
  • A participant expresses uncertainty about calculating the compressor capacity without knowing the dimensions of the tubes, stating a need for 10,560 liters/hr at 116 PSI and questioning the validity of their CFM calculation of 6.21.
  • Further clarification is provided on how to convert actual flow rates to standard flow rates, emphasizing the importance of temperature and pressure in the calculations.
  • Concerns are raised about compressor duty cycles and the need for appropriate storage tank sizing to accommodate operational factors.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the calculations, as there are uncertainties regarding tube dimensions and the implications of the calculated CFM. Multiple viewpoints on the calculation methods and requirements for compressor sizing are presented.

Contextual Notes

Limitations include the lack of tube dimensions, which affects the ability to calculate the required air flow accurately. The discussion also highlights the need for conversions between actual and standard flow rates, which depend on specific temperature and pressure conditions.

Who May Find This Useful

Individuals interested in air compressor sizing, pneumatic systems, or those involved in engineering applications requiring precise air flow calculations may find this discussion relevant.

dtaftm
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Hi,

First time user here.

I was hoping someone could help me calculate the CFM of air needed for an Air Compressor to air-clean 16 tubes. The Compressor is connected to a header that has 116 PSI of Pressure. The header is connected to 16 thin pipes that have nozzle tips with a 1.5 inch diameter. The nozzles release air in sequence, one at a time. We are counting on 220 liters per valve with 3 releases per hour. In other words 660 liters per hour per valve.

Thank you
 
Last edited:
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I would do the following:

(a) Figure out the volume of each tube.
(b) Divide the volume in Part (a) by 1/2 second. This will be your actual flow rate per tube.
(c) Convert your flow rate in part (b) to standard conditions.
(d) Establish the time interval between each tube firing.
(f) Multiply the volume in Step (a) by 16.
(g) Multiply the time interval in Step (d) by 16.
(h) Divide the volume in Step (f) by the time in Step (g).
(i) Convert your flow rate in part (h) to standard conditions.
(j) Size your compressor for the larger flow rate from Step (c) or (i). Include a safety factor between 1.25 to 1.75 depending on how confident you are in your input.
 
Thanks Edge,
The problem is that I don´t have the dimensions of the tubes yet.
Here´s the situation. I need to purchase an Air Compressor to supply the air to the new system that we´re going to implement. I know that we will need to supply 10,560 liters/hr at 116 PSI of pressure. Can I calculate the capacity of the air compressor that I will need to supply that much air to the system with just that info. I´m getting 6.21 CFM which seems way to little.
Thanks
 
dtaftm said:
Thanks Edge,
The problem is that I don´t have the dimensions of the tubes yet.
Here´s the situation. I need to purchase an Air Compressor to supply the air to the new system that we´re going to implement. I know that we will need to supply 10,560 liters/hr at 116 PSI of pressure. Can I calculate the capacity of the air compressor that I will need to supply that much air to the system with just that info. I´m getting 6.21 CFM which seems way to little.
Thanks
Your 10,560 liter/hr = 6.21 is your "actual" flow rate. Compressors will be rated for "standard" flow rate. You can convert your actual flow to standard with:

Standard Flow Rate = \frac{T_{STD}}{T_{ACT}}\frac{P_{ACT}}{T_{STD}} Actual Flow Rate

T_STD = 60 degF
P_STD = 14.7 psia
P_ACT = (116 + 14.7) psia
T_ACT = your actual flowing temperature
 
Great, Thanks for your help Edge.
 
Many compressors don't like a high duty cycle, something like 40% comes to mind. Too many starts per hour should also be avoided, so be sure to size your storage tank to accommodate both factors depending on the motor and compressor selected.
 
Thanks Mike
 

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