Different Types of Fire Alarm Initiating Devices

Different Types of Fire Alarm Initiating Devices The fire alarm initiating devices in a fire alarm system detects signs of fire and activates an alarm. They are the system's triggers and its most visible element.

Initiating devices are connected to the alarm system’s control panel via 2- or 4-way circuits and are under the control panel’s constant surveillance. In the event of an activation of an initiating device, the panel determines the activation and goes into an alarm state, sounding the alarm in the building and alerting the emergency service provider.

The most common fire alarm initiating devices are smoke detectors, sprinkler water flow switches, manual pull stations, and more.

Various types of fire alarm initiation devices Initiating devices can be classified into two categories: automatic initiating devices and manual initiating devices.

Automatic initiating devices: Automatic initiators are those that are triggered automatically as soon as the appropriate conditions are met. They include: Smoke detectors Fire sprinkler water flow switches Heat detectors Automatic initiating devices come in spot type and linear type.

A spot detector focuses only on the area where it has been installed, whereas a linear device covers a wide area of space but communicates with a single control unit. A standard ionization smoke detector is an example of a spot type, while a light-obscuration photoelectric smoke detector is an example of a linear type.

Spot types are less expensive, but their connections to fire alarm systems must be made separately, and more devices are needed to adequately cover an area. While linear types are more expensive, they only require one connection to the fire alarm system, and one unit covers a larger area.

Manual initiating devices: A manual device is one that must / can be manually activated when a fire emergency occurs. Manual pull stations are, of course, meant by this.

As soon as one of these devices is activated by their respective conditions (smoke, heat, water flow, or manual adjustment), the control panel detects the change and initiates the alarm, which triggers a visual and audible alarm to alert building occupants.

What does the fire alarm initiation devices do?

In most fire alarm systems, there are multiple types of initiating devices, each with its own role and triggering requirements. It is necessary to install each initiating device separately and connect it to the circuitry of the fire alarm system.

Below is the brief explanations of how each type of initiating device works:

Smoke Detectors Initiating devices like smoke detectors help fire alarm systems respond quickly before a fire has the chance to develop fully. It is because fires cause smoke early on in their development, long before water sprinklers or heat detectors activate.

The two most common types of smoke detectors are ionization and photoelectric.

Ionization smoke detectors measure airflow current using ionized air held within a sensing chamber.

As smoke penetrates the chamber, it reduces the current. The detector activates when the current drops enough.

A photoelectric smoke detector detects smoke by using light in one of two ways.

A light-scattering method involves arranging a light source and sensor (both within the detector) such that the sensor cannot detect the light under normal conditions. When smoke enters the detector, it scatters or reflects light back into the detector. The sensor is activated when enough light hits it.

The second photoelectric method is light obscuration, in which the light source and detecting sensor are usually separate components. When a light beam is projected into the sensor, the sensor remains inactive as long as it receives the light. In the event that smoke from a fire obscures the light beam from the sensor, the detector will be activated.

Sprinkler Water Flow Switches Sprinkler water flow switches detect the flow of water through the pipes of a fire sprinkler system.

The water in the pipes of a sprinkler system typically sits stagnant when it isn't activated. When a fire sprinkler is activated by a fire-induced temperature, water flows through its system and out of its open end. A sprinkler water flow switch detects this change in water activity and alerts the fire alarm panel that the sprinkler system has been control activated.

Heat Detectors Heat detectors are the oldest automatic initiating devices and are still the most reliable, though they are slow to respond to fires. The most common types are fixed temperature detectors and rate-of-rise detectors.

Fixed-rate heat detectors activate when the room temperature reaches a specific, predetermined level.

In the event of a fire, it can take a long time before the temperature reaches this predetermined level, so the initiating device may not respond for some time after a fire has started.

In contrast, a rate-of-rise heat detector activates when the temperature around it rises 15 degrees or more in a minute. As a result of this rapid increase in temperature, the air inside the detector's chamber expands, pressing a metal diaphragm against contacts that trigger the detector's activation.

Manual Pull Stations As portrayed in many films, manual pull stations allow individuals to initiate the fire alarm in case of an emergency.

There are two types of pull stations: single-action and dual-action. Single-action stations require only one physical action: pulling a lever. A dual-action station, on the other hand, requires two actions, such as breaking a glass cabinet containing the lever or lifting a covering.

Choosing the right fire alarm initiation devices Having a company like Quickshipfire who has made it their business to know the ins and outs of these systems and devices is essential to effectively protecting your property and those who live or work there.

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