This is denoted as Fire Detection and Protection system FDP in some other definitions. FDP provides early and reliable detection of fire or gas, wherever such events are likely to occur, alert personnel and initiate protective actions automatically or manually upon operator activation.
Basically the system consists of field-mounted detection equipment and manual alarm stations, a system logic unit for processing of incoming signals, alarm and HMI units. The system shall be able to process all input signals in accordance with the applicable Fire Protection Data Sheets or Cause & Effect charts. FDP SIL requirements typically range from SIL 2, SIL 1 or defined as a system without SIL requirement pending on the risk analysis
Fire Detection
Fires can be detected from flame, smoke or heat
1. Flame Detector:
A flame detector should alarm on the presence of a flaming fire
• Infra-red (IR) Flame Detectors: The detector relies on infra-red radiation produced by flames. The level and wavelength of infra-red radiation varies depending on the fuel of the flame being detected
• Camera-based Flame Detectors: Camera-based flame detectors use visual pattern recognition techniques to recognize flame shapes. They can relay a picture of the area under detection to the control room operator, thus minimizing the need to send staff towards a risk.
2. Smoke Detection:
Heat detection is used where ambient temperatures or environment preclude the use of smoke detection. Linear heat detectors offer wide area coverage, with some linear heat detectors discriminating alarms both by temperature and location.
• Point Heat Detection: These detect high temperatures at a given point. Descriptions have changed over time.
• Linear Heat Detectors: These detectors detect heat somewhere along the length of the device. They vary from the simple destructive types that burn through and signal an alarm to sophisticated systems that monitor the actual temperature at a particular point.
3. Heat Detection:
Smoke detection technology ranges from the battery-powered detectors on sale generally to sophisticated visual, camera-based detection systems.
• Point Smoke Detectors: Point detectors detect smoke at a fixed point. They need to be placed where smoke realistically could travel in the event of a fire.
• Camera-based Smoke Detectors: Detectors that monitor the characteristic shape of smoke. Continuous light is essential for smoke detection.
Gas Detection
In general, gas detection is divided into combustible gas detection and toxic gas detection.
1. Combustible Gas Detection:
Two mainstream technologies are available – infra-red absorption and catalytic types.
• Infra-red Absorption Combustible Gas Detection: The technology uses the absorption characteristics of the hydrocarbon molecules to infra-red light. The more hydrocarbon molecules are present, the higher the absorption of infra-red radiation.
• Catalytic Gas Detectors: Catalytic detectors rely upon burning gas in a sintered chamber. For this reason they are only available as a point detector or as part of a multi-point aspirating system.
2. Toxic Gas Detection:
• open path (Laser) gas detection is in development
3. Oxygen Depletion detection:
The detection methodology is different from the other gas detection applications – an alarm is indicated when the oxygen setting falls to a low level.
Fire Alarm control panel
All above devices could be addressable or conventional, but all of them will be received by FACP (Fire Alarm Control Panel) equipped by a CPU with direct connection capability to ESD trough a serial or high speed connection gate.
Typical actions from FDP systems are:
• Alert personnel;
• Release fire fighting systems;
• Emergency ventilation control;
• Stop flow of minor hydrocarbon sources such as diesel distribution to consumers;
• Isolate local electrical equipment (may be done by ESD);
• Initiating ESD and PSD actions;
• Isolate electrical equipment;
• Close watertight doors and fire doors