Teledyne 6600 - Manual (Page 94)

1-4 Part III
Part III Model 6600
Teledyne Analytical Instruments
The procedure to set up the optical bench, the signal processing front-end
amplifiers, the standardization of outputs, and alarm systems are described in
separate sections for each access.
2.3 The Automatic Zero System
The sample may contain chemicals which are not oil, but absorb UV
energy at the measuring wavelength used for oil analysis, thereby interfering
with the oil analysis (their signals add to the oil signal, which is the only signal
of interest).
The automatic zero system is included to discriminate the two signals. It
involves an electronics circuit, which drives the signal developed by the
interfering, non-oil, background chemicals below zero on an hourly basis.
The electronics zero circuit works in conjunction with a specially designed
sample system.
The sample, which contains oil and background chemicals, is fed to the
sample return port, where it progresses to the various subsections for enhance-
ment in order to present the sample to the measuring cell in such a way so as to
maintain the highest degree of accuracy for oil measurements.
2.4 From B71046-0 (or customer’s) piping schematic
Each of these subsections with piping flow components are identified
with rectangular dotted lines to indicate their importance based upon a
particular oil measurement application.
For Example, there are 4 basic process sampling considerations:
1. Required use of a homogenizer/dearator and filter assemblies for high
oil range (>20ppm high background applications).
2. Required use of filter assemblies for low oil (<20ppm oil, high
background).
3. Required use of back-flush solenoids for low oil range, very low
background applications
4. Required use of a pump assembly for low pressure (<10 psig) or no
gravity feed applications).
In general, but not without exceptions, the following applications could
involve items 1 through 4 above or combinations thereof.A. 0-20ppm oil
down to 0-10ppm oil in very clean waters such as steam condensates, cool-
ing waters, clear sea waters: (3 and 4, if no sample pressure or gravity feed
available).
Note: Assume sample inlet contains dissolved oil and is homogeneous.