Test Gas Driving Force; Barometric Pressure; Relative Humidity - Ametek mocon AQUATRAN 3/38 Operator's Manual

AQUATRAN 3/38 Operator's Manual Theory of Operation

Test Gas Driving Force

The driving force of the test gas has a direct effect on the water vapor transmission rate. The driving force of
the test gas is affected by the water vapor concentration (RH) of the test gas and the ambient Barometric
pressure.

Barometric Pressure

Barometric pressure influences the output of the water vapor sensor. The water vapor sensor vents to the
atmosphere. The pressure in the water vapor sensor is affected by changes in the barometric pressure.
The instrument automatically compensates all transmission rate data to eliminate the effect of barometric
pressure on the reported transmission rate.

Relative Humidity

The amount of water vapor some materials (such as nylon, cellophane and ethyl vinyl alcohol) are exposed
to significantly affects the water vapor transmission rate of the barrier. The barrier properties of some of
these materials can be permanently affected by prolonged exposures to significant amounts of water vapor.
The AQUATRAN 3/38 provides the capability to test these types of materials in a controlled "wet" test
environment. A Relative Humidity for the Test Gas between 0% and 90% RH can be specified.
MOCON, Inc. Revision G D-3