Vaisala DSS70A Technical data

DSS70A Portable Sampling System
and Sampling Cells for DM70

www.vaisala.com

The DSS70A provides a compact solution for field checking dew point where direct
measurement is difficult. Typical applications for the sampling system are metal
treatment and plastics drying processes.

DSS70A portable
sampling system

The DSS70A is designed to provide
dew point sampling exibility for the
DM70 hand-held dew point meter. For
processes at atmospheric pressure,
a battery powered pump is used to
extract a gas sample. For pressurized
processes up to 20 bar, the sample
is measured at process pressure
and then reduced to atmospheric
pressure for venting or re-direction,
bypassing the pump. In all cases, the
sample gas passes through a lter to
remove particulate contamination
before measurement. Flow through
the system is controlled and
monitored with a needle valve and
ow meter.

The DSS70A is easily connected to
an appropriate sample point with
tubing (typically 1/4” or 6 mm).
The measured dew point must be
below ambient temperature to avoid
condensation in the system. Gas

temperatures higher than +40 °C
(+104 °F) should be cooled with a
short PTFE (included in the DSS70A
system) or stainless steel tube prior
to entering the DSS70A.

Sampling cells for
pressurized processes

The DM70 can easily be connected to
pressurized processes. In addition to
direct pipeline installation, a variety
of sampling cell options are available
for gas sampling.

The DSC74 sampling cell is the
recommended choice. It has a variety
of connection adapters that allow
several different ways of installation.
The quick connector with a leak
screw allows a very fast connection
for compressed air lines. Additionally,
two thread adapters are available for
the inlet port.

The DSC74B is a two-pressure
sampling cell, which enables
measurements in both process and

ambient pressure. This sampling cell
is especially suitable for dew point
measurements in SF
DMP74C probe.

The DMT242SC is a basic sampling
cell. The DMT242SC2 is a sampling
cell supplied with welded Swagelok
connectors for sampling in a 1/4”
pipeline.

The sampling cells (from the left)
DMT242SC2, DMT242SC and DSC74 can
be used to connect the DM70 to sample
gas flow. The DSC74B (right) is a two­pressure sampling cell that can be used
for measurements in either pressurized
or ambient pressure. The cooling/venting
coil is included in the DSC74C sample
cell, but is an option for all sampling cells.

gas with the

6

Sample gas

inlet

Sample gas

outlet

Valve

Removable

flow limiter

Measurement

in gas

pressure

Sample gas

inlet

Sample gas

outlet

Valve

Removable

flow limiter

Measurement in
atmospheric

pressure

Diffusion coil

DSC74B

DSC74C

Sampling Cell
for Td Probe

Sampling Cell
for Td Probe

DSC74B

Sample Gas

Inlet

Sample Gas

Outlet

Sample Pump

Flow meterNeedle Valve

Sampling Cell

for Td ProbeFilter

DSS70A

Technical data

DSS70A Sampling System and
DSC74B/C Sampling Cells

The DSS70A sampling system includes a filter to clean the dirty
sample gas and a needle valve to control the sample flow rate
with the flow meter. A sample pump is used to generate a sample
flow from processes at ambient pressure.

DMCOIL cooling/venting coil
DMT242SC sampling cell

pressure limit 10 MPa (100 barg, 1450 psig)

DMT242SC2 sampling cell with Swagelok

connectors

pressure limit 4 MPa (40 barg, 580 psig)

Material for all sampling cells stainless steel AISI316

DSS70A sampling system
Operating conditions

Operating gases air, N2 and other non-toxic,

inert gases
Dew point range -70 °C ... Tamb (-76 °F ... Tamb)
Inlet/outlet connection 1/4" Swagelok
Operating temperature

ambient temperature 0 ... +40 °C (32 ... +104 °F)

Process gas temperature

with PTFE tube at +20 °C (+68 °F)
(included in the DSS70A)
with stainless steel tube specification according to

Maximum gas temperature at inlet +40 °C (+104 °F)
Operating pressure

with pump 0.6 ... 1.2 bara (8.7 ... 17.4 psia)
pump disconnected 0 ... 20 bara (0 ... 290 psia)

max. +200 °C (+392 °F)

stainless steel tube specification

The DSC74B sampling cell enables the measurement of the
sampled gas either in gas pressure up to 10 bar or in atmospheric
pressure depending on the gas inlet and outlet. The DSC74C
is like the DSC74B but with an additional coil to avoid back
diffusion, the effect of surrounding moisture, in dew point
measurements in atmospheric pressure.

Sampling cells technical data

DSC74 sampling cell for pressurized gases

pressure limit 1 MPa (10 barg, 145 psig)

DSC74B two pressure sampling cell

pressure limit 1 MPa (10 barg, 145 psig)

DSC74C DSC74B with DMCOIL cooling/

For more information, visit
www.vaisala.com or contact
us at [e-mail]

venting coil

General

Battery operation time for pump 8 h continuous use

battery can be recharged using DM70 charger

Filter 7 mm inline filter cartridge 1/4"

Swagelok SS-4F-7

(spare part order no. 210801)

Materials

wetted parts Stainless steel

carrying case ABS plastic
Case size (W x D x H) 430 x 330 x 100 mm
Weight 5.5 kg (12 lbs)

Electromagnetic compatibility

EN61326-1, Generic Environment.

Ref. B210833EN-A ©Vaisala 2009

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to change without notice.