The Thin Film Evaporometer consists of two chambers: an outer chamber, which serves as a constant temperature
environment, and an inner chamber where the evaporation of the sample takes place. The temperature, humidity and
airflow within the inner cabinet are closely controlled. Many users find it more convenient to utilise the automated
compressed air drying system rather than to chemically dehumidify an available air supply or use dry nitrogen. The
actual site of the evaporation of the test material is a filter paper disc suspended from an optical Electro-balance
weight-sensing device. The output signal from the Electro-balance is fed to a digital meter. An analog output signal
from this meter can be wired to a recorder for minimum operator attention.
Summary of the Method:
The standard conditions of test of 25°C, 0 - 5% R.H., and 21 litres/min. air or nitrogen flow are maintained within the
Evaporometer. An accurately calibrated hypodermic syringe is used to dispense 0.70 mm of test solvent evenly onto
the surface of a 9-cm diameter filter paper disc within a ten-second period. The application of the test sample to the
filter paper disc and the subsequent evaporation of the material are continuously monitored by a digital meter. If a
recorder is used when the recorder pen returns to its original base line, or zero reading, evaporation of the sample is
complete. Knowing the chart speed, the time for each ten percent increment through 90% weight loss can be read on
the chart along with the 95% weight loss and extrapolated 100% weight loss evaporation times.
Evaporation results are reported either in time in seconds for each 10% through 90%, 95% and 100% evaporated, or as
a relative rate based on the 90% evaporation time for pure n-butyl acetate. In the latter case, the result is reported as
a Relative Evaporation Rate, with n-butyl Acetate = 1.0. The instrument is adjusted or calibrated by the user so that
the 90% evaporated time for n-butyl acetate (99% ester) is 470 plus or minus 10 seconds.
Evaporation (Inner) Chamber and Environmental (Outer) Chamber:
Temperature Range:
20 - 65° C (70 - 150° F), adjustable (lower temperatures may require refrigerated water).
Controls and Indicators:
Relative Humidity Indicator
Air Flow Rate Indicator
Two Adjustable Thermostats
Digital Temperature Indicators for inner and outer cabinets + including recorder output
주문하세요
