Fluid Components International GF90_GF92 - Manual (Page 58)

FLUID COMPONENTS INTERNATIONAL LLC http://www.fluidcomponents.com
GF Series Flow Meter Models GF90/GF92 54 Doc. No. 06EN003229 Rev. H
The GF90 has an optional VeriCal system that allows the user to check, or verify, the instruments calibration
without removing the flow element from the process installation. The diagram below shows the VeriCal
system.
VeriCal System
The basic system consists of the Transmitter assembly, flow element with internal VeriCal flow system, the
VeriCal regulator assembly and interconnecting hose. An optional pressure transducer is available. The
pressure transducer is mounted in the regulator assembly housing.
The VeriCal flow system delivers a repeatable flow through a nozzle across the primary flow element
thermowells. This is done while the flow element is retracted out of the process flow stream into the
insertion packing gland assembly. The flow element orientation is leveled. An inert gas controlled through
a precision regulator on the inlet side of a sonic nozzle is then injected across the thermowells. The factory
calibration gas is typically Nitrogen, but other gases maybe used.
The VeriCal system uses a sonic nozzle to consistently control the amount of calibration gas injected
on to the thermal flow transducer located on the end of the probe assembly. The operating principle of
the sonic nozzle requires the total or absolute pressure on the high side of the nozzle to be repeatable
+/- .20 psia. The pressure difference between the high side of the sonic nozzle and the process
pressure (low-pressure side of the nozzel) must be greater than 2X. When these two requirements are
met, a repeatable flow is injected on to the thermal flow transducer.
Optional VeriCal
In-Situ
Calibration
Verification