GDS 404+ Series, Operating Handbook

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Description
The GDS 404+ is a multi channel combustible and toxic gas monitor, which can accommodate up
to 4 sensor channels housed in wall mounting enclosure. Sensors may be added or removed as
required, but should be carried out with the power to the unit switched off. Each sensor continuously
monitors for gas, the display will show the gas type being monitored, the current gas reading and
the location of the sensors.
The gas alarms are activated at preset levels and will remain on until the gas clears, these in turn
activate the appropriate alarm relays. The fault indicator is initiated should the sensor connecting
lines become open/short circuit, or an electronic fault be detected.
The control unit requires an a.c. mains power supply and/or a low voltage d.c. power supply.
When both are provided the low voltage d.c. acts as a standby supply in the event of an a.c. mains
power failure.
MAINS ON LAMP (P) GREEN indicates that power is being supplied to the control unit.
When the optional standby battery is fitted loss of mains supply will result in the GREEN Mains ON
Lamp changing to RED.
GAS ALARM will be indicated by a red LED and display channel changing to a red background
with text indicationg the alarm status. Fault conditions are indicated by amber displays.
SOUNDER initiated in the presence of a fault or gas alarm condition.
TEST when pressed for 15 seconds alarm indicactions are activated. If pressed for a further 15
seconds alarm relays will change state.
RESET used to mute the sounder and reset alarms, gas alarms cannot be reset until the gas
concentration has decreased below the set alarm level.
ALARM RELAY INHIBIT Pressing the reset pad for 15 seconds will inhibit the alarm relays which is
indicated by the inhibit LED coming on. To remove the inhibit press the reset pad for 15 seconds,
the fault light will turn off.
ZERO POTENTIOMETER meter zero adjust when the sensor is monitoring a gas free atmosphere.
SPAN POTENTIOMETER used to adjust the meter indication to read correctly when the sensor is
subject to a test gas of known concentration.
ALARM SET SWITCH alarm trip points setting.
SENSOR CURRENT POTENTIOMETER sensor supply adjustment.