Yokogawa GC8000 Process Gas Chromatograph - Manual (Page 437)

<Appendix B Terminology>
App.B-4
IM 11B08A01-01E
Term Description Notes
Atmospheric-
Pressure Balancing
Valve
A balancing valve for sampling gases
This valve can be used for sampling gas.
As the fl ow rate changes, the compression rate of sample gas
changes, resulting in changes in the sampling volume.
This valve is used to prevent such changes.
Specifi cally, install this valve before the sample valve measurement
tube and turn it on to stop the fl ow of sample gas and then turn
on the sample valve. When the pressure in the sample valve
measurement tube reaches equilibrium with atmospheric pressure
at the outlet, turn on the sample valve and start sampling. These
procedures are carried out by setting each valve in the Method
setting.
Protection Device A device for detecting a pressure drop in the control unit to turn off
the power supply
The device is installed in a pressure-proof enclosure, and is
denoted differently in respective explosion-proof standards.
FM, CSA: Protection system (Explosionproof enclosure)
ATEX, IECEx: Safety device (Flameproof enclosure)
TIIS: Protection device (Flameproof enclosure)
Pressurized
Enclosure
An enclosure whose internal pressure is kept high with protection
gas
The electronic section of the control unit and the electronic section
of oven units 1-3 (including EPC enclosure) connect with one
another to form a single pressurized enclosure. A large isothermal
oven and isothermal oven in each oven unit are independent
pressurized enclosures.
Back-fl ush Valve A switching valve for back fl ushing
It uses RV.
Non Explosion-proof General purpose
Fore-fl ush Valve
A switching valve for fore fl ushing
It uses RV.
Flame Arrester A device for protecting against “fl ame runaway”
It is an explosion-proof device.
Protection Gas Air, Nitrogen, Carbon dioxide
Vortex Tube A cooler which uses compressed air
Manifold Regulator
Mesh Arrestor
Detects FID and FPD.
Utility Gas This term generally means all gases used in the device such as
protection gas, carrier gas, H
2
for FID and FPD combustion. In the
GC8000, it means the following gases except for protection gas and
carrier gas:
H
2
(for combustion)
Air (for combustion)
Make-up gas (H
2
, He, Ar, N
2
)
Stream Valve A valve which switches the streams through which samples of
measurement targets are fl owing.
Restrictor A needle-valve type variable resistor
It controls the fl ow rate of carrier gas or utility gas.
 Analysis Terminology
Term Description Notes
σ (sigma) This term means standard deviation, and indicates how far
individual data are from the mean.
1 σ: 68% of data are within the mean ±1 σ
2 σ: 95% of data are within the mean ±2 σ
The GC8000 generally ensures that repeatability is ±1% or ±2% of
full scale (2 σ).
2nd Edition : May 11, 2012-00