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| Measurement of gas, vapors, and liquids permeation rates through plastic films or membranes using optional capabilities of enhanced gas pycnometer (HumiPyc) - or gravimetric moisture sorption analyzer - V-GA. |
Several types of permeation experiments can be
carried out:
Method 1. After establishing vacuum on the downstream side
of the sample, and using ambient or higher pressure on the
other side, the transport rates of gas through the sample can
be measured by monitoring the pressure increase in the
pycnometer chamber of known volume.
Method 2. Using ambient pressure on the downstream of the
sample, and constant higher pressure on the other side, even
very resilient plastic films can be measured as the pressure
increase in the pycnometer chamber will be much less
affected by any non-zero leakage rate over prolonged time.
Method 3. Using replaceable charges in one of the adapters,
the gas permeation rates can be measured for a dry gas as
well as in the presence of 100 % saturated water vapors of
selected (organic) liquids vapors.
Method 4. Using a relative humidity (RH) generator, e.g.
V-Gen, the water vapor transmission rates (WVTR) can be
evaluated at different RH values from ambient to 50 psi
pressure.
Method 5. Placing a liquid on the studied membrane (at
ambient pressure or pressurized), and using vacuum on the
downstream side, pervaporation rates of the liquid though the
specimen can be measured at ambient or elevated pressures.
carried out:
Method 1. After establishing vacuum on the downstream side
of the sample, and using ambient or higher pressure on the
other side, the transport rates of gas through the sample can
be measured by monitoring the pressure increase in the
pycnometer chamber of known volume.
Method 2. Using ambient pressure on the downstream of the
sample, and constant higher pressure on the other side, even
very resilient plastic films can be measured as the pressure
increase in the pycnometer chamber will be much less
affected by any non-zero leakage rate over prolonged time.
Method 3. Using replaceable charges in one of the adapters,
the gas permeation rates can be measured for a dry gas as
well as in the presence of 100 % saturated water vapors of
selected (organic) liquids vapors.
Method 4. Using a relative humidity (RH) generator, e.g.
V-Gen, the water vapor transmission rates (WVTR) can be
evaluated at different RH values from ambient to 50 psi
pressure.
Method 5. Placing a liquid on the studied membrane (at
ambient pressure or pressurized), and using vacuum on the
downstream side, pervaporation rates of the liquid though the
specimen can be measured at ambient or elevated pressures.
Calculation of gas transport rates and permeability coefficient
The volume Vc of the pycnometer chamber can be easily measured (as in regular true density measurements). Knowing
the Vc , temperature, and applying the ideal gas law, the experimentally observed pressure rise versus time curve can be
converted to volume V of gas (at STP) that permeated through the film or membrane, yielding the curve V versus time.
Since the V is a product of permeability coefficient, effective area, pressure differential, and time divided by the
thickness of the specimen, appropriate re-plotting of the curve yields the permeability coefficient as the slope.
The volume Vc of the pycnometer chamber can be easily measured (as in regular true density measurements). Knowing
the Vc , temperature, and applying the ideal gas law, the experimentally observed pressure rise versus time curve can be
converted to volume V of gas (at STP) that permeated through the film or membrane, yielding the curve V versus time.
Since the V is a product of permeability coefficient, effective area, pressure differential, and time divided by the
thickness of the specimen, appropriate re-plotting of the curve yields the permeability coefficient as the slope.
To carry out permeation measurements using this
gravimetric sorption apparatus, the sample holding
cell can be suspended on the hang-down wire either
in vertical or horizontal position. The unique design
of the cell allows for exposing the suspended
membrane or film either to the vapor or to the
liquid. Water or other (organic) liquids can be used.
Using dry gas or a humidified gas source (RH
generator) with a regulated relative humidity level
the permeation or pervaporation process can be
studied at different RH and temperature conditions.
Using various RH levels instead of dry gas only for
circulating through the measuring chamber, unique
profiles of mass changes vs. time can be obtained.
Those profiles are invaluable for researches
studying the nature of transport processes through
membranes, plastic films, or other barriers.
gravimetric sorption apparatus, the sample holding
cell can be suspended on the hang-down wire either
in vertical or horizontal position. The unique design
of the cell allows for exposing the suspended
membrane or film either to the vapor or to the
liquid. Water or other (organic) liquids can be used.
Using dry gas or a humidified gas source (RH
generator) with a regulated relative humidity level
the permeation or pervaporation process can be
studied at different RH and temperature conditions.
Using various RH levels instead of dry gas only for
circulating through the measuring chamber, unique
profiles of mass changes vs. time can be obtained.
Those profiles are invaluable for researches
studying the nature of transport processes through
membranes, plastic films, or other barriers.
| Please contact us at: info@instruquest.com or support@instruquest.com for additional product information and sales inquiries |
The HumiPyc can be easily employed as a
gas permeability tester for measurements of
gas transmission rates through membranes,
plastic films, packaging materials, or other
barriers. Instead of a dedicated permeation
analyzer, addition of sample holding adapters
allows for measurement of gas transport
rates using manometric (pressure gradient)
method. Considering the 24-bit resolution
(less than 0.01 Pa), ability to change the
volume of pycnometer sample chamber, and
large pressure differential, a wide range of
gas permeation rates can be measured.
gas permeability tester for measurements of
gas transmission rates through membranes,
plastic films, packaging materials, or other
barriers. Instead of a dedicated permeation
analyzer, addition of sample holding adapters
allows for measurement of gas transport
rates using manometric (pressure gradient)
method. Considering the 24-bit resolution
(less than 0.01 Pa), ability to change the
volume of pycnometer sample chamber, and
large pressure differential, a wide range of
gas permeation rates can be measured.
Permeation
Cell
Cell
| PERMEATION |
2004 -2010 Copyright © InstruQuest, Inc. All rights reserved.
| I. Manometric (pressure gradient) method for measurements of gas transport rates through plastic barriers |
| II. Gravimetric method of permeation and pervaporation measurements |
| InstruQuest Inc. Scientific Instruments R&D |