‘Intelligent’ fixed-point gas detector

Paul Boughton

Crowcon Detection Instruments Ltd’s next generation of intelligent gas detectors and transmitters, the XgardIQ, is an intelligent and versatile gas detector. XgardIQ is available fitted with a variety of flammable, toxic or oxygen gas sensors or may be installed with a remote sensor housing up to 15 metres from the transmitter.

Providing analogue 4-20mA and RS-485 Modbus signals as standard, XgardIQ is optionally available with Alarm and Fault relays and HART communications. This comprehensive set of output interfaces ensures compatibility with virtually any control system from gas detection panels, to PLC’s, DCS’s and SCADA systems. HART communications enables diagnostic checking and maintenance using industry-standard communications tools remotely or locally in the hazardous area. The HART feature also enables XgardIQ to be logged and monitored automatically on asset management systems.

XgardIQ offers powerful features that help to minimise the time that operators must spend in the hazardous area performing routine maintenance functions. Sensor modules can be simply and quickly ‘hot-swapped’ without a hot-work permit, either for replacement with a new pre-calibrated replacement module, or for temporary removal to a safe area for calibration. Engineers thus avoid the need to carry compressed gas cylinders on-site and the sensor module can be tested and calibrated in the safety of a laboratory.

Users have the option to perform a quick and simple bump test rather than full calibration to verify that sensors are fully operational. Using the ‘Speedy Bump’ and ‘Smart Bump’ options, users can perform interim safety checks in minimal time, and using the minimum amount of gas.

XgardIQ utilises buttons and a bright OLED (organic light emitting diode) display rather than conventional magnets and LCD’s for configuration and adjustments. The OLED display enables status checking at a glance and from a distance; whilst the use of buttons avoids the risk of special tools (e.g. magnets) being lost and thus resulting in aborted calibration attempts.

Crowcon’s ‘+ve Safety’ feature confirms the detector is operating safely using a bright blue LED and screen messages. XgardIQ automatically alerts operators to any irregular events that may affect product integrity such as the ambient temperature or gas concentration exceeding sensor limits. Such events may harm the sensor but would remain undiagnosed on conventional gas detectors: the sensor may be rendered insensitive to gas without warning the operator. When the detector is working safely the blue +ve Safety LED remains on constantly, if any abnormal operating conditions are detected the LED will flash and a warning message will be displayed.

XgardIQ deploys novel features to simplify commissioning. In major new-build projects instruments are often installed many months ahead of the planned commissioning date. Some sensor technologies have a limited shelf-life and thus may not be operational after a long period of installation without being powered. The operator may thus face significant costs replacing sensors. XgardIQ can be installed without a sensor module, protected from the elements using a sealed ‘dummy’ module. Pre-calibrated sensor modules can then be supplied immediately prior to commissioning. The XgardIQ transmitter will automatically configure to the correct gas-type, scale and alarm levels when a sensor module is inserted.