Technical Description: Inlet
Rapid Multi-Stream Sampler
C-6
Prima PRO & Sentinel PRO Mass Spectrometers User Guide
Thermo Fisher Scientific
A restriction element (an orifice) is built into each six-way assembly
such that a line pressure of 1.0 bar(g) will give a flow around
150 cm
3
/min (Prima PRO) or 5 l/min (Sentinel PRO). Fine
adjustment of flow is achieved by adjustment of line pressure at the
calibration bottle regulator.
The incoming calibration gases connect to compression fittings on
the bottom of the calibration manifolds(s). By default, the fittings
will be the same size / type as fitted to the main RMS body.
Sample gases are connected directly to the RMS ports. The
connections are compression type. The standard types are 1/4”, 1/8”,
and 6 mm Swagelok, but other options may be available. The lines
may need to be heated, depending on the gas mixtures to be used.
Sample gas flow / pressure should be regulated externally to values
within the range indicated in
(the total flow should also be considered when selecting the exhaust
line size). Since the pressure required is quite low, it is preferable to
regulate the flow rather than the pressure. In the event of a flow
failure, the gas mixture in the common exhaust will diffuse back into
that port, and this will be the measured gas if that port is sampled. In
order to avoid this (and the possible reporting of false results), the
built-in flow sensor is used to verify that flow is within acceptable
limits (see
“Connection to the Mass Spectrometer”
), but note that
this can only be used to check the flow of the selected sample stream,
i.e. the flow can only be checked when that stream is sampled.
External flow monitoring (as part of a sample conditioning system)
can also be used and has the advantage that all streams can be
continuously monitored, but does require a flow monitor for each
sample line.
Gases must also be conditioned to remove particulate material down
to
2 µm. Liquids or materials that could condense at the operating
temperature of the RMS should also be removed. Consideration
should be given to fault conditions that may occur in the process or
sample lines and maximum and minimum ambient temperatures to
which the sample lines and RMS may be exposed.
Gas Connection
