Abstract: A fire and explosion suppression system comprises a source (5) of high pressure water which is fed to a misting nozzle (13) at one input of a mixing unit (6), and a source (14) of high pressure inert gas, such as nitrogen, which is fed along a pipe (20) to another input of the mixing unit (6). Inside the mixing unit (6), water mist, in the form of an atomized mist of very small droplet size is mixed with the pressurized gas and exits the mixing unit (6) at high pressure and high velocity along a pipe (22) and is thence discharged through spreaders (26, 28). The source (5) of the water is pressurized by a feed (30) from the source of pressurized inert gas. The mass flow rate of the water will therefore reduce as the pressure of the gas decays. This tends to maintain the ratio of the mass flow rate of the water to the mass flow rate of the gas constant. This is found to produce and maintain an advantageous distribution of droplet size in the discharged unit.

Abstract: In use of a UV gas discharge tube (such as used in flame monitoring apparatus), an electric field is periodically applied in the tube, each application of the field being followed by an ‘off’ period in which the field is removed. During this process, the mean value of the statistical lag Ts is measured over a predetermined time duration (the statistical lag is the time lag after each application of the electric field to the tube before conduction (if any) takes place). If the statistical lag lies within region I, the flame is judged to be present. If the statistical lag lies in region II, the flame is judged to be off (and a warning may be signalled). If the statistical lag lies in region III, a fault in the tube is signalled. This may be a “field emission” fault whereby free electrons are generated by the applied electric field, without the presence of UV radiation or it may be a “multiple counting” fault.

Abstract: A nozzle has a body with a central cavity from which a plurality of fire extinguishant fluid outlets extend. The outlets extend non-radially with respect to the central axis of the cavity, i.e. at least a portion of each outlet is inclined with respect to any plane parallel to and passing through the central axis of the cavity which intersects the portion of the outlet. The extinguishant from the non-radial outlets is thrown towards the walls of the chamber, along the paths. The jets of the fluid induce a rotational movement within the ambient fluid (for example, air) already present in the chamber, thus creating a vortex or rotational movement of the fluid within the chamber. In another embodiment, the vortex or rotational movement is generated by a nozzle assembly of generally cruciform configuration with three or more discharge tubes having outlets formed therein for discharging extinguishant in equi-angularly-spaced directions.

Abstract: A fire and explosion suppression system comprises a source (5) of high pressure water which is fed to a misting nozzle (13) or other water mist generating means at one input of a mixing unit (6), and a source (14) of high pressure inert gas, such as nitrogen, which is fed along a pipe (20) to another input of the mixing unit (6). Inside the mixing unit (6), water mist, in the form of an atomised mist of very small droplet size is mixed with the pressurised gas and exits the mixing unit (6) at high pressure and high velocity along a pipe (22) and is thence discharged through spreaders (26, 28). Separation of the mist production from the actual discharge of the mist, and the entraining and transporting of the mist between these two stages at high pressure and high velocity, produces an output mist of very small droplet size which is carried by the entraining and transporting high pressure gas into the area to be protected, enabling a total flooding capability.