YSI 9300 Photometer - Manual (Page 15)

12
5 TAKING PHOTOMETER READINGS
The photometer is very simple to use. Screen prompts guide the user
towards the test result. The following sections describe how to get the best
results from the instrument.
Program Numbers and Test Instructions
Each test is identified by a separate program number or named key. Program
numbers are shown in the test instruction sheets supplied in this manual. For
some tests, a choice of different programs is offered in order to get the result
in different forms (for example, for Nitrate - NO
3
or Nitrate Nitrogen - NO
3
-N).
In certain tests, such as free chlorine and total chlorine, the test can be
continued to a further stage. This is allowed for in the programming of the
photometer. In these tests, once the result of the first stage is obtained, the
‘Follow-On’ option may be selected to progress the test to the next test stage
or stages. The result will be calculated automatically.
These continuation programs have their own program number for reference
purposes although direct access to these programs may be restricted.
Sample Dilution (9500 Only)
The photometer has a sample dilution option. This enables a factor to be
entered when samples have been diluted to bring them within the measuring
range of the test. For example, if a five times dilution of a sample has been
made, then a dilution factor of x5 should be entered. The photometer will
multiply the observed result by this factor so that the correct result for the
original sample is displayed.
This option may be used in conjunction with the YSI Dilution Tube (YPT 512)
which enables dilutions of x2, x3, x4, x5 and x10 to be made. Higher dilution
factors may be entered but are subject to the limitation of the number of
digits available of the result display for each test. When the display capabilities
are exceeded, the symbol [xxx] will appear on the result display. The sample
should not be diluted prior to carrying out a pH test, or a Transmittance or
Absorbance reading.
Blank and Sample Tubes
A BLANK TUBE is needed each time the photometer is used. This enables the
instrument to be set automatically and compensates for any inherent color in
the test sample. It is important therefore to understand the meaning of the
term ‘BLANK TUBE'.