# Convert mg/s to SCCM (Standard Cubic Centimeters per Minute)

Hello,

Can anyone explain the procedure to convert mg/s to SCCM?

I'm working with an Alicat Mass Flow Controller, which regulates Argon (Ar) mass flow from 1 to 6 mg/s at 27o C or 300 K (room temperature).

For documentation purpose, I need mass flow in terms of mg/s, as well as, SCCM.

Thank you

Homework Helper
Hi,

mg/s is a mass flow and SSCM is a volume flow.
They are linked via the equation of state. For argon you can use the ideal gas law ##pV = nRT##

Key is to find the proper standard conditions (confusion lurks, so be sure to mention them)

FluidDroog
Hi,

BvU is correct. To derive the relationship of cubic centimeters to 'standard' cubic centimeters of gas, you use the gas law equation of state. Standard means Ps= 101325 Pa, Ts = 273.15 K and Zs = 1.
The derivation from reference [1] below should be sufficient to explain. It is a matter of setting the number of moles equivalent.
nx =ns => Px * Vx / (Zx*Tx) = Ps * Vs / Ts
Then solve for Vs = standard volume of gas

Molar flow is converted to standard volumetric flow via the standard molar volume 22.414 x 10-3 m3 mol-1 [2].
1 sccm = 0.74358 µmol/s [3].

To convert from mass flow (mdot) to molar flow (ndot):
ndot = mdot / MolarMass
To convert between molar flow rate and
sccm = (Standard Molar Volume) * (unit conversion factor) * ndot = 22.414 * 60e3 * ndot
In this case, the unit conversion factor is for seconds to minutes and m3 to cm3

References:
[1] Converting mass flow to volumetric flow rate. https://www.first-sensor.com/cms/upload/appnotes/AN_Massflow_E_11153.pdf
[2] Codata standard molar volume. https://physics.nist.gov/cgi-bin/cuu/Value?mvolstd|search_for=molar+volume
[3] NIST published conversion value from sccm to mol/s. https://tsapps.nist.gov/publication...4154&msclkid=d34cae6cabff11ec8093320a4d23498a

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