VICI 230 Dynacalibrator User Manual
Page 6
Introduction
As shown in Figure 1a, the carrier stream passes through scrubber #1 and line
filter LF1 (30µ) to differential pressure regulator DPR1. The scrubber contains
specially-activated charcoal designed for broad-based scrubbing action, and is
particularly effective in removing sulfur dioxide and other sulfur compounds.
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Figure 1a: Model 230 standard plumbing schematic
The differential pressure regulator and carrier flow restrictor FR1 together
provide a highly stable carrier stream flow rate to the permeation chamber.
The standard carrier flow restrictor consists of a disk with a 0.006" diameter
orifice. The flow rate through the orifice is a function of the pressure differential
across it, maintained at 3.2 psi by DPR1.
The output of the permeation chamber is fed to a mixing tee, where the calibrated
dilution stream is added to set the final concentration. The combined stream is
then fed through another tee to the rear panel overflow vent and span outlet.
For those analyzers sensitive to sample feed pressure, the overflow vent dumps
excess calibration gas to ensure that the analyzers receive span gas at near at-
mospheric pressure. The overflow vent is usually left open, but can be plumbed
to an external exhaust point. Any exhaust plumbing must be sized so as not to
increase pressure into the analyzer under calibration.
Note that the dilution stream passes through scrubber #2 and feeds into
differential pressure regulator DPR2. The differential pressure regulator
maintains a fixed pressure differential across dilution flow control valve FCV2
and dilution flowmeter FM2.
The flow rate through the flowmeter needle valve is a function of the differential
pressure across it and the setting of the dilution flow control valve. This differen-
tial is maintained at 3.2 psi by DPR2. The needle valve is adjustable at the front
panel. The calibrated output of the dilution flowmeter mixes with the perme-
ation chamber output to provide the final output concentration.