33
11.3
Remote Alarm Unit
An alarm relay unit (model
p
DR-RA) is available as an optional accessory for the
personal
DataRAM. The
p
DR-RA, when connected to the alarm output of the
personal
DataRAM, provides a switched output triggered by the alarm signal of the
monitor. This switched output (up to 8 amperes, 250 volts) can be used to activate or
deactivate other equipment (e.g. ventilation systems, machinery, etc.), or to control
remotely located (by wire connection) alarm indicators (e.g. buzzers, lights, etc.).
12.0 MAINTENANCE
12.1 General
Guidelines
The
personal
DataRAM is designed to be repaired at the factory. Access to the
internal components of the unit by others than authorized personnel voids warranty.
The exception to this rule is the occasional cleaning of the optical sensing chamber.
Unless a MALFUNCTION message is displayed, or other operational problems
occur, the
personal
DataRAM should be returned to the factory once every two years
for routine check out, testing, cleaning and calibration.
12.2
Cleaning of Optical Sensing Chamber
Continued sampling of airborne particles may result in gradual build-up of
contamination on the interior surfaces of the sensing chamber components. This
may cause an excessive rate of increase in the optical background. If this
background level becomes excessive, the
personal
DataRAM will alert the user at the
completion of the zeroing sequence, as indicated in Section 8.1, by the display of a
BACKGROUND HIGH message. If this message is presented, the
personal
DataRAM can continue to be operated providing accurate measurements.
However, it is then advisable to clean the interior of the sensing chamber at the first
convenient opportunity, proceeding as indicated below.
12.2.1
Model
pDR-1000AN
•
Remove the two screws on the top of the large protective bumper that covers the
sensing chamber (see Figure 1);
•
Remove the large protective bumper by lifting it firmly upwards and away from
the sensing chamber;
•
Remove the socket-head screws on the front and back black covers that were
exposed by removal of the large top bumper. Lift away the freed front and back
covers of the sensing chamber; set them aside carefully and such that they can be
reattached in the same position as they were previously; avoid touching the dull
black side of these plates;