Chemical Sampling Efficiency Of The Pils - BRECHTEL 4001-115V Instrument Manual

the droplet impactor. The droplets are driven radially outward to the edges of the quartz
disk where they are collected by a fine stainless steel mesh wick. A washflow is supplied
that continuously flows through the wick, mobilizing the collected droplets so the com-
bined wash/droplet flow can be withdrawn from the bottom of the droplet impactor. A
single peristaltic pump is used to deliver the steam generator liquid flow rate (1.4-1.5
ml/min), supply the washflow to the impactor, withdraw the liquid sample flow from
the impactor, and to withdraw liquid waste from the condensation chamber. The col-
lected liquid sample flow is passed through a gas debubbler to remove air bubbles and
delivered to either on-line analytical instruments for chemical analysis or to vials for
storage and off-line analysis.

Chemical Sampling Efficiency of the PILS

Brechtel has tested the chemical sampling efficiency of the PILS by simultaneously sam-
pling laboratory-generated ammonium sulfate particles with the PILS and a scanning
electrical mobility sizing system (SEMS). The total volume concentration from the SEMS
is multiplied by the density of ammonium sulfate (1.77
mass concentration sampled by the PILS. The results from a calibration test are shown in
figure 4. In the figure, mass loadings from the SEMS are shown as black lines/pluses and
those from the PILS are shown as the red histogram. 'T' denotes a time when the PILS
was transitioning from Filter to Sample mode (or vice versa), 'F' denotes a filter sam-
ple, and 'S' denotes a time where the three-way valve was set to sample. Arrows denote
times when the three-way valve was moved either from sample to filter mode, or from
filter to sample mode. The PILS data are adjusted in time to account for the liquid sam-
ple residence time in the instrument (roughly 300 sec). The average PILS-observed mass
concentration for the first two samples (denoted by 'S' in the figure) is 26.8
SEMS-observed mass concentration during the same time period is 26.6
ratio of the PILS- and SEMS-observed mass concentrations is 1.01, demonstrating good
agreement between independent techniques for measuring the particle mass concen-
tration. Note in figure 4 that the PILS-observed concentration does not instantaneously
decrease to zero when the three-way valve is switched from sample to filter. This is due
to the liquid sample residence time on the quartz impactor plate, in PEEK tubing, in the
debubbler, and in the peristaltic pump tubing. The total liquid sample residence time
varies depending on liquid flow rates, length and inside diameter of tubing. Residence
83-00009-01A PILS 4001-115V and 4001-230V
6.2 Theory of Operation
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