Manual Call Point (MCP) For Fire Alarm

Manual Call Point

Manual call point (MCP) is a trigger mechanism which helps in identifying the building or an area where fire has occurred in order to direct the attention of personals to that area. It is a part of fire alarm system.

MCP is basically a switch which is installed at various locations so that it is accessible to everyone who detects a fire to use it to inform others about the same. The switch is put in a mechanical box and a transparent glass is attached to the box using sealing rings. The box is labeled so that one can identify that it is to be used when there is an emergency fire situation. A hammer or similar tool is provided to be used to break the glass.

MCP is accompanied with a visual indication tool to locate the call; for example a plastic flag.  If someone breaks the glass to hit the switch then the plastic flag raises in the building thus helping in directing attention of the personals who will act against the emergency fire situation and also to alarm others to stay away from the building or the area.

A MCP unit can be combined with automation to automatically detect the fire using heat or smoke detectors and set off an alarm. MCP comes as wired installation and also as a non-wired or temporary installation. Both provide similar kind of protection and both can be automated. The temporary MCP has an added advantage that it does not require need for a specialized electrician and can be moved from one location to another. They run on batteries unlike the wired MCPs, thus they have to be checked every now and then to ensure that the batteries are working optimally.

The break-glass type of MCP is now being replaced with plastic elements because of the cost of replacing the glass in case of false fire detection. The plastic elements just have to be depressed firmly, they are easy to reset and can be used multiple times. They are also attractive since there is no danger to the person using it unlike the break-glass type MCP.

Types of Manual Call Point

(A) Button type:

The mechanism contains a button which needs to be pressed. The pressing of button raises a visual indicator and also informs about the change in loop current.

(B) Key type:

The mechanism contains a key hole instead of a button which calls on pressing. This mechanism contains key turning as a switch mechanism to alert everyone about the fire which has occurred. In case of false fire detection, the key can be used to easily reset the mechanism.

Uses of Manual Call Point

• Although MCP can be used in conjunction with the automated system, they were designed to be used manually. The MCPs are installed at various locations at regular intervals so that they are easily accessible by anyone in case they spot a fire occurring. They can be installed in any type of infrastructure.
• It is important to install MCPs even if an automatic fire detection system is already installed because automatic systems may be used during the day or at the night or when a process is running. Also, automatic systems have to be disabled if they have to be inspected. If a fire occurred in such scenarios the MCP will be very useful.

Reference/Image:- wikipedia, instrumentationtools, automationforum, rapidfireservices