Configuring the detector
How Many zones....?
The BX444 can be configured to provide one, two,
three or four zone protection. Sensors are enabled
and disabled by switching the zone select switches on
and off. To disable a zone move
the switch to the ON position. The
switches shown are in the zone
enabled position. When you have
made the switch change press the
reset on the BX444 fascia.
Gas or Carbon Monoxide...?
If the gas to be sensed is Explosive you must first
ensure that the correct sensor is connected to the
system. For instance, for Natural Gas SG590. Each
pair of switches shown
below corresponds to a
sensor. From left to
right, 1 to 4. To select
the Explosive Indication
on the fascia for a
particular sensor move
switch 1 to the ON
position and switch 2 to the off position. If another
zone is being used to sense carbon monoxide, again
ensure that the correct sensor is connected to that
zone for example CO200.
Pre-alarm adjustment
ppm/LEL & auto/ manual
reset selectors
Zone selectors
Explosive or Toxic
selectors
Terminal block 1
Terminal block 2
Continuous/pulsed main alarm
jumper
Printed Circuit board Layout
Select Toxic indication by moving switch 2 to the ON
position and switch 1 to the off position. In the above
picture this shows zone 1 Toxic, zone 2 explosive, zone 3
toxic, zone 4 explosive.
Pre-Alarm Sensitivity Adjustment
The Pre-Alarm can be adjusted, in the
case of Natural Gas or LPG, from 8% to
15% of the Lower Explosive Level (LEL).
For Carbon Monoxide, it can be adjusted
from 120ppm to 250ppm. Adjustment is
made using the pre-alarm potentiometer
marked PT1. To increase the sensitivity
turn the potentiometer away from the
central point either left or right. i.e. Central Position is 15%
LEL. Left or right 8% LEL.
Setting Main Alarm Memory function
The Main Alarm thresholds are not adjustable and are
fixed at 20% LEL for Natural Gas or LPG and 300 ppm
for Carbon Monoxide. The main alarm can be configured
to provide either a latching or an auto reset relay
actuation. For example to turn off gas valves or to boost
ventilation in car parks or areas containing carbon
monoxide. Should gas be sensed in boiler rooms
laboratories etc. the gas valve supplying the room will be
turned off by the detector. This must only be manually
reset following an alarm. However if the BX444 is being
used to control the levels of carbon monoxide in car parks
as long as the ventilation is boosted and the levels of
Carbon Monoxide drop there is no requirement to
maintain the alarm so the unit can be allowed to
automatically reset.
