Gerry02
Mechanical
- Jun 21, 2024
- 3
I am trying to calculate what the effect on vacuum would be from an o-ring sealing water - vacuum for different o-ring materials looking specifically at permeation.
I found the following formula for calculating o-ring permeability:
Q = K A (P1 - P2) / D
Q is the permeation rate (cm3/sec)
K is the permeation coefficient (cm3 cm/sec cm2 atm)
A is the area (cm2)
P1 - P2 is the pressure gradient (atm)
D is the thickness (cm)
I thought i could use the formula for gas load (Q = P.S)
My issue is the units for Q do not match. Q for the permeability equation is volumetric flow rate where as the Q for the gas load equation is pressure - volumtric flow rate.
Its my first time working with vacuum so still getting up to speed with the technology.
Thanks
I found the following formula for calculating o-ring permeability:
Q = K A (P1 - P2) / D
Q is the permeation rate (cm3/sec)
K is the permeation coefficient (cm3 cm/sec cm2 atm)
A is the area (cm2)
P1 - P2 is the pressure gradient (atm)
D is the thickness (cm)
I thought i could use the formula for gas load (Q = P.S)
My issue is the units for Q do not match. Q for the permeability equation is volumetric flow rate where as the Q for the gas load equation is pressure - volumtric flow rate.
Its my first time working with vacuum so still getting up to speed with the technology.
Thanks