Table of Contents
Advertisement
TCD Analyzer
3.4 Gas Connections
The gas fittings are accessed through the port on the back side of
the analyzer chassis, as shown in Figure 3-2. These connectors use
tubing. The standard analyzer includes no gas control valves inside the
main chassis. A sample system must be provided for introduction of zero
and span gas, as well as sample gas, into the sample path, and for
controlling the flowrates through the sample and reference paths of the
analyzer. Internal Auto Cal vales are available as an option.
3.4.1
S
S
AMPLE
YSTEM
The unit is manufactured with 1/8" inch tubing fittings as
ports. The customer must provide matching fittings.
For best results, use the recommended piping system. Select a
flowmeter that can resolve 40-50 cc/min (0.08 scfh) for the reference
path of the analyzer and select a flowmeter that can resolve 150 cc/min
(0.3 scfh) for the sample path of the analyzer.
Note: The sample-line pressure regulator should be installed as
close to the sample point as possible to minimize sample-
line lag time.
3.4.2
P
RESSURE AND
Appropriate pressure reducing regulators must be installed at all
gas supply sources. To minimize flowrate adjustments the pressure
regulators on the supporting gas supply cylinders should be adjusted to
provide the same output pressure as the sample line regulator.
The gas pressure input should be reasonably well regulated.
Pressures between .35 and 3.5 bar (5 - 51 psig) are acceptable- .7 bar (10
psig) is normal if the pressure, once established, will keep the flow
constant during analysis, and within 50-200 cc/min (between 0.1 and
0.4 scfh). A needled valve or restrictor is needed before the analyzer
inlets to set the flow to required range.
Note: Gases lighter than air have a flowrate higher than
indicated on the flowmeter, while gases heavier than air
have a flowrate lower than indicated. Values can range
from one half to twice the indicated flowrate.
For example: For hydrogen or helium, set the flowrate to
Teledyne Analytical Instruments
D
ESIGN
F
R
LOWRATE
EGULATION
Installation
1/8"
15
Advertisement
Table of Contents
