Specifications

69
DSS 10 Configurable Sample Systems
for the DMP 248 and HMP 238 Dewpoint
Transmitters
DEWPOINT MEASUREMENTS IN EXTREME
CONDITIONS
When the operating environment is not suitable for
the moisture probe to be directly installed in the
process an alternate solution could possibly be found
with a Vaisala sampling system.
The sample system allows for greater measurement
accuracy and stability by controlling the temperature,
pressure and filtration levels to optimize the perfor-
mance of the sensor. The sampling systems can be
configured with cooling coils to reduce temperatures
above 176°F (80°C), filters to remove particulate
down to 0.01 micron in size, along with valves, flow
meters, pressure gauges and vacuum pumps to
control flow rates and pressure levels.
Vaisalas sample systems are easy to install, operate
and virtually maintenance free. Each system comes
mounted on a steel plate that is fixed to the wall.
Stainless steel tubing is then connected from the
process tap to the sample system to allow gas flow
from the process to the sample system. Power will
need to be supplied to the dewpoint transmitter as
well as the vacuum pump, if ordered. The system
will only need a one time adjustment of valves to
achieve the desired gas flow rates and pressure
levels.
SAMPLE SYSTEM COMPONENT OPTIONS
 Sample cell
House the DMP248 dewpoint probe
 Cooling Coil
Cool high temperature process gas to room
temperature prior to the moisture sensor
 Inlet ball valve
Acts as a shut off between process tap
and sample system
 Inlet 3-way ball valve
Manual control of two-process sample taps
tied into one sample system
 Vent ball valve
Acts as a drain if condensation occurs or as a
pressure release for a closed loop system
 Outlet needle valve
Adjustable control valve for system pressure
and flow
The DSS 10 sample system offers the flexibility and
customization necessary to meet various demanding
applications. The systems may contain any, or all, of
those items listed on the DSS 10 order form in the
1999 price list. When unsure about which compo-
nents to select, and why, consult a Vaisala represen-
tative.
 Sintered filter
Protection against pipe scaling and other
particulate larger than 7 microns
and other particulate larger than 0.01 microns
 Pressure gauge
Pressure indicator when sample system
is pressurized
 Coalescing filter
Protection against pipe scaling, liquid carry-over,
 Flow meter
Indicates flow rate through sample system
 Flow switch
A relay that indicates when there is low flow
through the system
 Vacuum pump
Pulls a sample of gas from the process through
the sample system