Standard nozzle sizes are 12 mm, 16 mm or 19 mm, or as near thereto as possible, so as to make full use of the maximum discharge capacity of the fire pump(s)
- For accommodation and service spaces, the nozzle size need not exceed 12 mm.
- The size of nozzles used in conjunction with a portable fire pump need not exceed 12mm.
- All nozzles should be of an approved dual purpose type (i.e. spray/jet type incorporating a shut-off.
The approximate discharges in m3 /hour, (which for practical purposes may be considered equivalent to tonnes/hour), through well designed plain nozzles of 12 mm, 16 mm and 19 mm for pressure drops of 2.1, 2.5, 2.7, 3.1 and 4 bars are given in the following table:
Pressure discharge for various nozzle diameters m3/hour
Where dual purpose nozzles are provided, they should be capable of a performance in the plain jet setting as indicated above, without undue spread, and have a throw of at least 12 m. The spray setting should produce a reasonably fine spray, which can be arranged to form a curtain, behind which, it would be possible to approach a fire. An acceptable diameter of the cone of spray would be 5 m at a distance of 2 m from the end of the nozzle.