Vaisala DMT132 - Manual (Page 21)

Chapter 3 _______________________________________________________________ Installation
VAISALA _______________________________________________________________________ 19
CHAPTER 3
INSTALLATION
This chapter provides you with information that is intended to help you
install the DMT132.
Selecting the Location
It is important that the conditions at the point of installation represent
well the gas to be measured. Temperature changes do not affect the
dewpoint measurement, but pressure changes will have an effect on
dewpoint. 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 DMT132 and no
additional filtering is needed due to very dusty or oily gas. Oil as such is
not harmful for the HUMICAP® 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 20 bar
a
/ 290 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 25.
The DMT132 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.