A Manual Call Point is a device used for the manual initiation of an alarm. Manual Call Points are commonly known as MCP. The activation of this alarm by an MCP is achieved by the use of a pull station or call point or by breaking a simple piece of glass using a hammer.
This action of a pull station or call point or breaking a simple glass using a hammer would then sound the evacuation alarm for the particular building or zone. This action of a pull station or call point or breaking a simple glass using a hammer will also give an alert to the main panel where the emergency response team will be present. Since MCP are manual fire alarms, MCP needs human intervention for activation. This makes MCP different from the automatic fire alarm system.
The manual call points (MCP) can be used with the automatic fire alarm system as a part of an overall fire detection and alarm system. MCPs are also called manual fire alarm pull stations or break glass units. These MCPs are used to notify the occupants in the zone or building that a fire or other emergency exists within the area. MCPs are connected to a central fire alarm panel. This panel is then connected to an alarm system in the building.
Manual call points find initiates an alarm signal. MCP can operate with a simple button press. In some cases, when a glass is broken, it actuates a micro switch. MCPs are a part of the automatic alarm system. The indicator on the monitoring unit provides a visual indication that facilitates quick identification of call points.
How does this system of MCP work?
The working principle of MCPs is really simple. MCP has a micro switch which is maintaining close contact through a surface of the MCP or a breakable glass. Whenever someone presses this surface of the MCP or breaks the glass, the micro switch changes its contact.
This contact is continuously monitored by a system known as Fire & Gas System (PLC). When this microswitch’s contact changes its state, an alarm is generated by the control system (PLC). A responsible person will reach the location of the MCP as described by the description of the MCP in the alarm or the tag number in the alarm which came on the display when the MCP is actuated.
The main use of this MCP is to seek help from the response team when anyone wants help in case of a medical emergency or other emergency.
Selection Criteria for Manual Call Points
For using manual call points in industries, there are some minimum requirements and standard specifications which are to be followed. They are:
- The MCPs must be of the break-glass type. This is because it provides protection against accidental operation.
- MCP must have a key-operated test facility for periodic testing of the alarm contacts without removing or breaking the glass.
- It is also important that the method of operation is indicated clearly by a concise permanent inscription inside the MCP unit. All the words should also be clearly visible from the outside including the word “FIRE”. For example, “Fire: Break Glass”.
- The glass must be designed in such a way that it does not cause any injury to the operator when the MCP needs to be operated.
- The MCP must come back to its normal position once the frangible element is replaced.
- The sealing rings must be provided on the glass of the MCP to secure the glass properly.
- The call points must be equipped with current limiting resistors. These resistors must be permanently fitted inside the unit and not wired into the terminals which are provided for field wiring.
- The operation of the call point must cause a change in the loop current. This change in current will be detected at the fire and gas control panel.
- The manual call points used in hazardous areas are encapsulated over the contacts by the use of IS monitoring circuits.
- At all the manual call points, a brass hammer or a similar kind of operating device must be made available with the means of attachment. The brass hammer does not produce a spark when struck against the body of the call point.
- All manual call points must have a red epoxy finish on them.
Applications of Manual Call Points
- The manual call points are used for manually activating the fire alarm activation and manual extinguisher control.
- MCP finds use in public buildings, industries, senior citizen homes, power stations, airports, educational institutions, healthcare facilities, etc.
Where should Manual Call points be located?
Manual call points for fire alarms are generally located along the escape routes. It facilitates to trigger of the alarm without delaying the evacuation process or putting the person at unnecessary risk. Call points should be located at the following points as per the regulatory requirement (B5 5839).
- On every floor of a building
- Between 30 meters from any point in the building
- In a perspicuous & accessible location
- Not above 1.4 meters from the floor
- Additionally, in the high-risk areas