Teledyne 326, 327 and 328 - Oxygen analyzers User Manual

Page 25

Teledyne Analytical Instruments

Installation

Model 326/327/328

3-5

across the NC and C contacts will always see a closed circuit (switched on)
when the relay is de-energized.

Each set of relay switch contacts (NC-C-NO) is assigned its own barrier

strip terminal inside the control unit. Wiring should be no larger than 18
gauge because the external load must be limited to 3 amperes (non-induc-
tive) per relay. All wiring should be installed in the conduit port and be
appropriately identified on the control unit outline diagram.

3.3 Gas Connections

The sample input, vent, and purge connections are located on the

underside of the analyzer case. Both are identified on the outline diagram.
TAI suggests that Teflon sealing tape be used as a sealant, rather than pipe
dope. Be careful that mated fittings are not cross-threaded before applying
force with a wrench. For most applications, the gas connector block in the
analyzer is aluminum and can be damaged more easily than the fitting it is
mated to.

3.3.1 Pressure Reduction and/or Regulation

Unless span gas is specified, the standard 326R analyzer requires only a

pressure-reducing regulator installed at the sample point, and the necessary
interconnecting tubing. The regulator should be set between 5 and 50 psig;
10 psig is nominal.

For the 327RAC/RBC and the 328RC, TAI recommends that the

sample pressure be reduced at the sample point

at the sample point

at the sample point to between 34.5 kPag and

344 kPag (68.9 kPag nominal). If the magnitude of the sample pressure
does not exceed 689.5 kPag and is reasonably stable, a simple throttle valve
will be satisfactory. If, on the other hand, the pressure is in excess of 689.5
kPag or vacillates over a wide range, a metallic diaphragm regulator should
be used. Do not use a regulator that is equipped with an organic dia-

Do not use a regulator that is equipped with an organic dia-

phragm under any circumstances.

For positive-pressure sampling systems, the analyzer may require a

pressure reducing regulator installed at the sample point, and the necessary
interconnecting tubing. The regulator should be adjusted to provide a
nominal pressure of 10 psig.

Other configurations may also be used in specially-designed systems:

motorized pumps and aspirator syphons driven by air, water, or a combina-
tion of the two, are common methods of drawing sample from processes
which do not allow positive pressure sampling. The piping diagram in the
drawings section at the rear of the instrument instruction manual is specific