Let’s first review the components that make up a gas detection system as it will help determine the overall architecture and design of the gas detection system.

Controller: The controller is the device that receives and displays the gas concentration and alarms from each sensor.  The controller typically provides a readout of the gas concentration, audible and visual alarms, alarm relays and analog and/or digital signal outputs. There are single channel controllers to monitor Single sensor and multi-channel controllers to monitor many sensors.  Much like a fire detection panel, the controller is usually mounted outside the monitoring area, to allow safe viewing of gas readings from a central location.

Sensors: The sensor is the device that detects and measures the gas. There are many types of sensors; each designed to detect a particular gas or groups of gases.  A sensors range of detection (gas range) is usually determine by an established health or safety standard.  Most sensors have a typical life of 1-4 years, but some can last longer depending on the application and type of sensor.

Transmitter (Amplifier):  The transmitter is a devise that conditions and/or boosts the signal from a sensor to the controller.  Some sensors require a transmitter to operate while others connect directly to the controller.  If a sensor is more than a few hundred feet from the controller, a transmitter is usually needed. There are exceptions to this rule so please consult our technical support group at toll free 1-877-832-4737.

Stand-Alone Sensor/Transmitters:  There are stand-alone sensor/transmitters that can be used with or without a controller.  These stand-alone sensors generally have a display, alarm relays and a signal output.

Sample Pump: Pumps may be added to a sensor to allow remote sample capability.  Difficult to reach areas or areas that are prone to flooding are reasons to consider a sample pump.

System Considerations:

• List of gases you wish to detect.
• Safety monitoring or process control?
• Distance between each sensor and the controller.
• Gas Range and alarm settings required for each gas.
• What do you wish to control with each alarm?
• What is the approximate area (cubic feet) you wish to detect gas within?
• Do you plan on mounting the equipment Indoor or outdoor?
• Intrinsic Safety Rating-Classified on non-classified environment?
• Environmental Factors: Moisture, high particulate (dust), aerosols, extreme temperature.

Controller Considerations:

• Is a controller needed?
• Mounting Options; Wall Mount, Rack mount, Desk top?
• Enclosure type; intrinsically safe, explosion proof, NEMA rated?
• How many alarm points (levels) are needed per sensor?
• How many relays are needed for each alarm point?
• What is the amperage and voltage rating of each alarm relay?
• What action(s) take place at each alarm level?
• How will each alarm action be initiated; Relay, analog or digital output?
• Signal Inputs needed to communicate with each sensor.
• Signal Outputs needed to communicate with DCS, SCADA, PLC or some other devise.
• Environmental Factors: Moisture, high particulate (dust), aerosols, extreme temperature.

Sensor / Transmitter Considerations:

• Gas type and Gas range of each sensor.
• How many sensors are needed for each gas?
• Sample draw or diffusion sensor?
• Is sample conditioning needed; if so what type of conditioning?  Example: A coalescing filter may be needed to remove excessive moisture.
• Is a display needed at the sensor?
• Are local alarm relays needed at the sensor?
• Environmental Factors: Moisture, high particulate (dust), aerosols, extreme temperature
• Enclosure type; intrinsically safe, explosion proof, NEMA rated?
• Damaging gases: Are there any gases that may be harmful to the sensor or equipment present in the Environment? For Example: Silicone, Leaded Fuel, Chlorine, and Halogenated compounds (Freon) can damage a catalytic combustible sensor.