VICI 450 Dynacalibrator - Manual (Page 7)

3
Introduction
When the calibrator mode is changed to ZERO, SPAN 1, or SPAN 2 – either by
remote command or the mode selector switch – SV3 energizes to interrupt the
normal sample input and substitute the calibrator output stream through the
stream outlet port. In these modes, excess calibration gas is dumped out the
overflow vent to ensure that analyzers sensitive to sample feed pressure receive
zero or span gas at near atmospheric pressure. The overflow vent is usually left
open, but can be plumbed to an external exhaust port. Any exhaust plumbing
must be sized so as not to in crease pressure into the analyzer under calibration.
SAMPLE
INLET
TEE MIXING
TEE
OVERFLOW
VENT
SV2
CHAMBER
VENT
NO
NC
C
NO NC
C
SV3
STREAM
OUTLET
Standby mode
CARRIER
DILUTION
SAMPLE
INLET
TEE MIXING
TEE
OVERFLOW
VENT
SV2
CHAMBER
VENT
NO
NC
C
NO NC
C
SV3
STREAM
OUTLET
Zero mode
CARRIER
DILUTION
SAMPLE
INLET
TEE MIXING
TEE
OVERFLOW
VENT
SV2
CHAMBER
VENT
NO
NC
C
NO NC
C
SV3
STREAM
OUTLET
Span mode
CARRIER
DILUTION
Figure 2: Model 450 output flow configurations