Converting scfm to lb/hr, which density should I use?

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Discussion Overview

The discussion revolves around the conversion of cubic feet per minute (cfm) to pounds per hour (lb/hr) in the context of air density at different conditions. Participants explore the appropriate density values to use for these conversions, considering both standard and actual conditions.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant states that for air at 150 F and 125 psig, the density is 0.61 lb/ft³, while at standard conditions it is 0.0765 lb/ft³, questioning if this means multiplying by 0.0765 lb/ft³ and 60 min/hr to convert 500 cfm to lb/hr.
  • Another participant expresses uncertainty about the definitions of cfm and scfm, indicating a need for clarification.
  • A participant provides a link to a Wikipedia page that explains standard cubic feet per minute, suggesting it may help clarify the terms.
  • One participant asserts that to convert cfm to lb/hr, one should multiply by the actual density, and to convert lb/hr to scfm, one should divide by the standard density.
  • Another participant notes that the only invariant aspect in such calculations is the mass.
  • A participant shares another link to the same Wikipedia page, humorously suggesting that legislation should be created to standardize units of measurement.

Areas of Agreement / Disagreement

Participants express differing views on the appropriate density to use for conversions, and there is no consensus on the definitions of cfm and scfm. The discussion remains unresolved regarding the best approach to these conversions.

Contextual Notes

There are missing assumptions regarding the conditions under which the densities are applicable, and the discussion does not clarify the specific definitions of cfm and scfm, which may affect the conversion process.

Frankenstein19
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Homework Statement
If I convert from cfm to scfm, should I use the density of the material at standard conditions or what the conditions the material is actually at?
Relevant Equations
lb/hr = cubic feet/min * 60 min/hr * lb/cubic feet
For air for example at conditions 150 F and 125 psig, density is 0.61lb/ft3

At standard conditions it's 0.0765lb/ft3

If I convert 500 cfm to scfm, does this mean I should multiply by 0.0765lb/ft3*60min/hr to convert to lb/hr?
 
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It is not clear to me what are cfm and scfm, never seen these units (I can guess, but I prefer to be sure).
 
To convert CFM to lb/hr, you multiply by the actual density. To convert lb/hr to scfm, you then divide by the standard density.
 
In general the only invariant thing in such calculations is the mass.
 

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