The purpose of the branch is to increase the velocity of water and may be defined as “A Metal fittings between hose and the nozzle converting pressure energy to provide the nozzle with a solid jet – of water for fire fighting.”
Types of controlled branches:
Hand controlled branch:
Also known as “London Branch,” it has equipment to either shut down, alter spray, or simultaneously get jet or deliver jet and spray. Each function can be controlled independently.
By turning the anti – clockwise rotating collar, the spray can vary from a 300 cone to a 1800 flat sheet. However, the jet size is not adjustable and depends on the 16 mm or 19 mm nozzle size. It can be as high as 22 mm as the branch’s 1 D would not allow.
This branch can give variable size spray or jet that can be shut off as needed. The spray could vary from an intense mist to a complete shut – off at an angle of 180.
Fog nozzle branch:
This branch can be adjusted to give a straight jet water stream, a fine or coarse spray, and shut off completely.
The fine spray is, therefore, the name in the form of mist or fog. The control operations are facilitated by a floating rotary valve connected to the handle. To prevent the entry of any foreign material wire mesh is provided in a cylindrical tube in between the rotary valve and the male instantaneous coupling so that the holes of the spray nozzle or spray head, are not blocked.
The spray head is detachable and held in position by the spring loaded interlocking arrangement.
With this type of hand – controlled branch, the spray head or spray nozzle can be extended with extension piece or low – pressure applicator can be connected to combat small oil fires or directly discharge the fog to the burning surface.