OZONE MONITOR BMT 932 Manual, Rev. 02/2021
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1 General Description
The OZONE MONITOR BMT 932 is a state-of-the-art UV photometer for measuring and
monitoring ozone content of the ambient air. The ozone content is displayed in ppm
v
or µg/m³
(at 1 atm and 20°C), a dimension requiring temperature and pressure compensation. This is the
reason why the OZONE MONITOR BMT 932 is temperature and pressure compensated, of
course.
The instrument may be ordered with 1, 3, or 6 sample channels. Switching from channel to
channel is automatic, or manual via a push button.
The BMT 932 is designed to allow direct handling of three independent EMO circuits (Emergen-
cy Machine Off) with multi-channel monitors to facilitate the direct control of ozone generators
in workplace safety applications.
Since the application of the BMT 932 mainly is TLV (Threshold Limit Value) monitoring, con-
tinuous and safe operation of the instrument is the predominant requirement. This is the reason
why the BMT 932 has two scrubbers (the scrubber is one of the most important elements of an
ambient ozone monitor). And it has a built-in ozone generator for intermittent automatic testing
the function of the utility scrubber. When this scrubber fails in completely removing the ozone
from the sample ozonated by the ozone generator, the instrument automatically switches from
the utility scrubber to the reserve scrubber, and at the same time activates the Scrubber Alarm
indicating a scrubber failure.
The ozone concentration is displayed on a two-line 40-character alphanumeric display. The con-
centration unit can be changed during operation. Additional modifiable parameters are among
others :
Alarm parameters (two alarm thresholds for each channel, alarm latching, audible, opening
or closing relays, EMO circuit to alarm assigment)
Date and time
RS-232 interface parameters
These parameters can be set with the three pushbuttons on the front panel as well as by connect-
ing the serial interface to a Windows-PC running the software BMT 932 Link, which is supplied
with each instrument. Another way of configuring the instrument is to use the so-called Link
Mode via the serial interface.
Active sample channels for automatic sampling can be chosen as desired. It is also possible to
choose only one channel for measurement. Switching from automatic to single channel sampling
is easily done by just pressing the ENTER key.
The sample gas flow rate is maintained constant by a pump which is automatically controlled by a
built-in electronic flow meter. In case the pump fails and the flow rate drops, the warning signal
LOW FLOW is activated indicating a pump failure.
The highly stable UV radiation source has a life expectancy of well over 5 years. Via an automatic
control loop the radiation output of the UV lamp is precisely maintained constant during its ser-
vice life. When the lamp's performance drops significantly, the early warning signal LAMP LOW
is activated indicating that the lamp should be replaced by a new one during the next few weeks.
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