Accessory Enclosure
Installation, Commissioning and Maintenance Instructions
The Accessory enclosure enables flammable gas detectors with a pellistor mV bridge output to be
connected to Gasmaster or any other 4-20mA control panel. These instructions refer to Crowcon’s
Gasmaster system, but can be used as guidance for any similar control system. Other 4-20mA
type gas detectors or fire detectors should be connected directly to the Gasmaster panel.
The Accessory Enclosure contains between 1 and 4 sensor amplifier PCB’s which convert the
sensor mV bridge signal to a 4-20mA signal which can be monitored by the control panel. The
amplifier PCB’s are designed for use with catalytic beads rated at 2V dc 300mA (approx).
To enable an Accessory Enclosure to be used, the Gasmaster must be fitted with the appropriate
connector and wiring loom. If the connector was not fitted when the Gasmaster system was
ordered, it can be purchased and fitted at a later date (see spare parts and accessories section for
the part number).
1. Installation
The Accessory Enclosure should be fixed to a wall adjacent to the control system using the 6mm
(1/4”) mounting holes provided. The enclosure is supplied with a 75cm (3’) lead fitted for simple
connection to the Gasmaster panel. The flammable gas detectors should be connected directly to
the Accessory Enclosure as shown in Figure 2. An earth continuity plate is fitted for bonding cable
glands.
Figure 1 Accessory Enclosure Layout
Cable glands (supplied
by customer)
Connection lead to
Gasmaster
Screw-lock
connector
Sensor amplifier
PCB’s (1 to 4
may be fitted)
M07642
Issue 4
January 2015
