envea STACK 602, User Manual

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STACK 602 9 Maintenance
ENVEA UK Ltd
(PC-000848-MA Issue 5, December 2021)
vii
8.
Quality Assurance and Self-Tests
8.1 Available Sensor Tests
The control unit provides the maintenance and testing functions outlined below.
Function Purpose
Maintenance Mode
(Start/Stop) Puts the sensor heads in maintenance mode, allowing
cleaning and maintenance of the sensor.
Sensor Self-tests
(Zero/Span
checks)
Automatic internal opacity sensor self-tests to check the
validity of measurements.
Comms Check
Checks communications between the control unit and
sensor.
Calibration
To carry out calibration using results from isokinetic
sampling (see
Appendix B
on page
61
).
Set Up To configure brightness and sensitivity.
8.1.1 Performing Sensor Self-Tests
The QA/Self-Tests screen allows the status of self-checks to be reviewed for each
device. These can be set to run automatically and can also be forced manually
(for example, during installation or maintenance).
Frequency: Span checks for the CEM are implemented automatically and are per -
formed by varying the light intensity in the Transmitter head. The Zero check
involves measuring the variation with no Transmitter light present. The automatic
sensor self-tests are performed alternating every hour (Zero test = Light OFF,
Dynamic Opacity Span test = Light 50%).
Sensor self-tests can also be activated manually (on demand) from the QA/Self-
Tests menu screen. To perform a test, press the Activate button next to the
required test. For each test, the display alternates between PASS and FAIL, and
the numerical result of the test; the meaning of these numbers is explained below.
8.1.2 Sensor Test Pass Levels
Sensor Test
Minimum
Pass Level
Optimum
Pass Level
Maximum
Pass Level
Opacity Light OFF (ZERO) – 0% 5%
Opacity Light 50%
(SPAN)
40% 50% 60%
Dynamic Opacity (Dust)
Light OFF (ZERO)
– – –
Dynamic Opacity (Dust)
Light 50% (SPAN)
– – –