Teledyne 402REU - Hydrocarbon analyzer - Manual (Page 8)

Teledyne Analytical Instruments 1-2
Chapter 1 Model 402R-EU
To best suit the needs of the purchaser, specialized designs are avail-
able. Details of the design differences may be found in the various draw-
ings (outline, assembly, schematic, wiring, and piping diagrams) in the
drawings section at the rear of the manual. The standard analyzer is
housed in a sheet steel equipment case that has been designed for flush-
mounting in a 19" rack.
CAUTION: Since the measured component for the 402R-EU is hydrocarbon
content, and since hydrocarbon lubricants and conditioners as
well as synthetic plastics are common to instrumentation
supply processes, utmost precaution must be taken at all times
to specify hydrocarbon-free gases, regulator diaphragms and
supplies.
1.3 Sampling System
All components used to control the sample and supporting gases, as
well as the combustion portion of the detector cell, are located inside,
behind the electronics control panel. The basic analyzer consists of an
isothermal chamber containing the pressure regulators, pressure gauges and
flow restrictors. The temperature within the chamber is maintained at
125°F by a heating element. The regulated temperature of the chamber
insures stable gas flow. An optional sample selector module is an integral
gas selector panel inside the instrument enclosure for conveniently switch-
ing between sample and calibration gases. When installed, it is part of the
isothermal chamber. The bypass flow is also controlled from this optional
panel.
1.3.1 Input Porting
The analyzer is equipped with ports for the introduction of air, fuel,
zero, span, and sample gas.
1.3.2 Sample Flow Control System
Stable sample flow is achieved by maintaining a constant pressure
across a restrictor through the use of a back-pressure regulation system,
which includes an adjustable regulator, pressure gauge, throttle valve, and
flowmeter. The throttle valve and flowmeter are included so that the
bypass flow required by the back-pressure regulator can be limited. With-
out these controls, a high sample point pressure would result in unneces-
sary sample waste through the back-pressure regulator.
The components of the system are arranged so that no dead volume is
present in the sample path to the detector cell. This guarantees rapid re-
sponse to changes in hydrocarbon concentration—a fact that can be dem-