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SCFM or ACFM: Is there a difference?
Productie automatiseringsmachines -
Houston, Texas
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Seztec USA specializes in metering technologies for process
measurement & control and environmental monitoring applications. We
are a small team of experienced engineers with the mission to deliver
outstanding value to our customers through an extensive portfolio of
affordable, reliable, and smart metering solutions. Products &
Services: We have focused our business portfolio to deliver metering
systems for flow, level, temperature, pressure, moisture and energy
measurement with wireless data transfer capabilities. Our products and
services help our clients achieve their measurement and digitalization
goals. Industries we serve: Industries that we focus on include Water
& Wastewater, Manufacturing, Agriculture, Environmental, Food &
Beverage, HVAC, Power, Chemical & Petrochemical, Mining, and more.
Visit our website to explore our comprehensive range of products and
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Defining ACFM, SCFM Gas Flow
Concepts
When designing your flow station for gas flow measurements, the most
common confusion begins with CFM, SCFM, and ACFM. All three have
similar definitions, but relay totally different data. Let us explain
how.
CFM stands for Cubic Feet per Minute and is normally used to indicate
the working capacity of a pump, compressor, or a blower.
ACFM stands for Actual Cubic Feet per Minute and is a unit of
volumetric flow rate of a gas displaced by a pump at operating or
present conditions of temperature and pressure.
Whereas SCFM is also a unit of volumetric flow rate that stands for
Standard Cubic Feet per Minute. SCFM is the measured gas flow with
respect to fixed reference operating conditions and is the most useful
measure of gas flow. These reference conditions may vary based on
industry and geographical region, but commonly used reference
conditions are:
(1) Temperature @ 68°F
(2) Pressure @ 14.5 PSIA
The reason experts around the world introduced the concept of
measuring gas flow in SCFM is to standardize all gas flow
measurements. This is because, the volume a gas occupies is dependent
on its temperature and pressure. For example, a fixed mass of air will
occupy larger volume at higher temperature and will undergo
compression (smaller volume) at higher pressures.
This means person “A” measuring 1 ACFM of air at their operating
temperature T1 and pressure P1 is not the same “amount” or “mass” of
air as person “B” measuring 1 ACFM of air at a completely different
set of operating conditions (temperature T2 and pressure P2).
Therefore, when gas readings are obtained in SCFM
or “fixed” reference conditions, gas flow measurements will be
standardized or remain consistent and will mean the same regardless of
the operating conditions.
How to obtain gas measurements in SCFM?
To obtain gas flow readings in SCFM, firstly, the gas is measured in
ACFM at actual and “known” operating conditions. Meaning a continuous
temperature and pressure input is required to track actual operating
conditions. The flow computer then uses the below mathematic
correction factor, or a variation thereof, to convert ACFM to SCFM
that utilizes the actual and reference temperature and pressure
values:
Ts: Standard Temperature
Ps: Standard Pressure
Ta: Actual Temperature
Pa: Actual Pressure
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Compressed Air and Gases
Green Play Ammonia™, Yielder® NFuel Energy.
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