Vaisala DMT143 - Manual (Page 22)

USER'S GUIDE ____________________________________________________________________
20 ___________________________________________________________________ M211435EN-E
Selecting the Location
It is important that the point of installation represents well the gas to be
measured. Temperature changes do not affect the dewpoint measurement,
but pressure changes will have an effect on the measurement. All leaks in
the system must be eliminated to avoid ambient humidity affecting the
measurement.
Direct installation to the measured gas is the recommended installation
method if the temperature of the gas is suitable for DMT143 and no
additional filtering is needed due to very dusty or oily gas. Oil as such is
not harmful for the DRYCAP
®
sensor, but response time may be slower
if there are oil particles in the system, or if oil is collected to the filter
over a longer period of time. The maximum measurement pressure is
50 bar
a
/ 725 psi
a
(absolute pressure) for direct measurement.
If the gas temperature is higher than the specified maximum operating
temperature of the transmitter, gas sampling and cooling it to ambient
temperature (for example, 20 °C / 68 °F) is recommended. Note that the
dewpoint temperature must be clearly lower than the ambient
temperature to avoid condensation in the sampling line. Sampling from
the process is easy by using Vaisala sampling cell options; see section
Sampling Accessories on page 26.
The DMT143 is light in weight, which means that it can be installed in a
sample pipeline in the sampling cells without the need of any additional
mechanical support. You can use a standard G1/2" T-shaped pipe fitting
(not available from Vaisala) when installing DMT143 into a pipeline.
Installing the Transmitter
1. Remove the yellow transport protection cap from the transmitter.
1202-122
Figure 5 Removing the Transport Protection Cap