Table of Contents
Advertisement
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 out of the
system.
Program Numbers and Test Instructions
Each test is identified by a separate program number or named key. Program
numbers are shown in test instruction sheets supplied with the instrument or
reagent systems. For some tests, a choice of different programs is offered in
order to give the option of the result in different forms (eg for Nitrate - NO
or
3
Nitrate Nitrogen - NO
-N).
3
In certain methods, the test can be continued to a further stage - for example
in the tests free chlorine and total chlorine. This is allowed for in the
programming of the photometer. In these tests once the first stage result is
obtained, the 'Follow-On' option may be selected to progress the test to the
next program stage or stages and 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.
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 colour in
the test sample. It is important therefore to understand the meaning of the
term 'BLANK TUBE'.
The BLANK TUBE is a test tube filled with the water being tested only. It is
important to use the actual water to be tested to provide a true comparison for
the test results.
The term 'SAMPLE TUBE' is used to describe the tube containing the water
sample to which the reagents have been added in accordance with the
appropriate test instructions. This tube is used to take the photometer reading.
Light Cap
A light cap is provided with the photometer. This cap fits over the test chamber
and prevents stray light reaching the photodiode.
It is NOT necessary to use the light cap when using the photometer indoors or
under shaded outdoor light. The light cap should however be used when
working out of doors in strong sunlight. The light cap is also recommended
when carrying out turbidity-based tests such as the cyanuric acid test, under
bright or variable lighting conditions. Test instructions indicate when the light
cap should be used.
7
Hide quick links:
Advertisement
Table of Contents
