Sample Air Flow Control System; Pils On-Line Analysis; Ion Chromatography Systems - BRECHTEL 4001-115V Instrument Manual

6.5 Sample Air Flow Control System

drain bottle. Be sure to drain the bottle before each use.
6.5 Sample Air Flow Control System
The sample air flow at the inlet of the PILS is controlled using a critical orifice brazed
into the barbed air exhaust fitting attached to the PILS droplet impactor. The user should
periodically measure the air flow into the PILS (with steam generation on for a minimum
of 30 minutes) to verify that the measured air flow rate agrees with the expected value
within +/-3% over the 11.0 to 16.0 lpm range. Be sure to record the measured flow rate
for use in the calculation of ambient species concentrations.
The PILS air exhaust flow is saturated with water vapor at about 35 C. Take care to avoid
filling vacuum lines with condensed water at cooler temperatures downstream of the
PILS.
6.6 Using the PILS with On-line Analysis Systems
The Brechtel PILS may be used with a wide variety of chemical analyzers to perform on-
line measurements of aerosol chemical composition. The PILS has been coupled to a
variety of IC systems, water-soluble organic carbon analyzers, liquid-capillary waveg-
uides for absorption and species-specific probes and other unique sensing systems.

Ion Chromatography Systems

The majority of PILS applications involve the use of ICs. It is important to use the PILS
peristaltic pump to draw liquid sample through the IC sample loop and not to 'push'
sample through the loop, as the peristaltic pump could pressurize the IC column during
injection. The PEEK tubing from the debubbler that would normally be connected to the
peristaltic pump should instead be connected directly to the IC sample loop inlet port
fitting of the IC. The sample outlet port of the IC sample loop should be connected to the
PILS peristaltic pump liquid sample flow channel. In this way, the peristaltic pump will
draw liquid sample through the IC sample loop, allowing the IC to inject small volumes
of sample when required without negative interactions between the two instruments.
Keep the PEEK tubing runs as short as possible to minimize pressure drops and residence
times through the system. A guard column or in-line liquid filter (0.5 micron pore size)
should be used to protect the column from insoluble material. Currently, there is no di-
rect communication between the PILS and the IC. The PILS is operated continuously and
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