The Forgotten Gadget That Protected Buildings from Catastrophic Fires!
September 15, 2024
Source: Reddit
Traditional fire protection systems used mechanical systems to contain fire and one of the mechanisms used was the glass bulb fusible link. This is a rather fascinating brass item which is usually marked with the Simplex brand and this is an essential piece of fire fighting equipment. The one featured here marked ‘Simplex Type A 100Lbs’ would have been used to hold fire shutters, dampers or valves in open state.
The design is straightforward but effective: the link comprises of two similar metal pieces held together by a glass tube containing a fluid. When the temperature increases, it leads to increase in volume of the liquid. At a certain pressure level (for instance at the level marked ‘100Lbs’) the glass vial containing the air bursts open. The breaking of the vial makes the brass frame to crack and let go of whatever fire-blocking mechanism it was holding to open. Whether the system was designed to close the shutters, let out the damper or open the fire door, the fact that this system was simple and dependable made it a lifesaver.
The screws which hold the metal part on the glass vial were tightened and capped with mortar in order not to be tampered or loosened. These fusible links once installed did not need any form of maintenance as they worked through the process of heating and cooling.
Even though these glass bulb fusible links were widely used in industrial and commercial applications, they are not as popular as the solder-based fusible links of the present. Still, the older design is a good example of fire safety engineering in early ages and can be seen in many buildings to this date.
