BS EN 615:2009 pdf free download – Fire protection一Fire extinguishing media – Specifications for powders (other than class D powders).
K.1 General
The following small-scale fire test also found in EN 1568-3:2008 [2], Annex I may be used to show whether incompatibility between extinguishing powders and foams may exist.
This test is carried out on the foam in question, and then repeated after the fuel has been covered in powder. If the increase in extinction time is equal to or greater than 25 % longer than the result without powder, then the combination of powder and foam may be considered to lead to an unacceptable loss in efficiency.
Likewise, a reduction in burnback time by 25 % or more when powder is used would indicate that the foam and powder are incompatible.
(500 ± 1) g powder is weighed into a 180 pm sieve, placed on a sheet of paper or cardboard. The sieve is held over the fuel, and the cardboard or paper removed. The powder is then evenly distributed over the surface of the fuel from a height of (150 ± 10) mm. The fuel is lit not more than 60 s after the powder has been spread over the surface of the fuel. The fire-test is carried out following the method in EN 1568-3:2008 [2], Annex I.
K.2 Apparatus
K.2.1 Circular fire tray of brass as shown in Figure K.1 with dimensions as follows:
a) internal diameter at rim (565 ± 5) mm;
b) height of vertical wall (150 ± 5) mm;
c) height of conical base (30 ± 5) mm;
d) thickness of vertical wall (1,2 ± 0,2) mm,
with a turned over rim, and a drain point with valve at the centre of the conical base.
NOTE The tray has an area of approximately 0,25 m2.
The fire tray is supported approximately 1 m above the ground on a steel frame with four legs. The tray is normally placed beneath a suitable fume extraction hood which will extract the smoke without interfering with the fire.
K.2.2 Burn-back pot of brass with dimensions as follows:
a) internal diameter at rim (120 ± 2) mm;
b) internal depth (80 ± 2) mm;
c) thickness of wall (1,2 ± 0,2) mm, with a turned over rim, and fitted with four studs at the base to give an overall height of (96 ± 2) mm. A chain fitted
to the rim allows the burn-back pot to be lifted using a metal rod.
K.2.3 Foam making nozzle as shown in Figure K.2 which has a nominal flow rate of 5,0 1/mm at 7 bar when tested with water. It is fitted with an adjustable collar to allow foam to be ejected from the side of the nozzle and thus vary the foam flow rate through the outlet. The foam flow rate can also be controlled by adjusting the pressure applied to the foam solution.
K.2.4 Fuel
An aliphatic hydrocarbon mixture according to the following specification:
a) distillation range: 84 °C to 105 °C;
b) maximum difference between initial and final boiling points: 10 °C;
c) maximum aromatic content: 1 % w/w;
d) density at 15 °C: (700 ± 20) kg/m3.
NOTE I The normal value of surface tension of the aliphatic hydrocarbon mixture measured in accordance with
ISO 304 at (20 ± 1) °C is 21 mN/rn-I to 22 mN/m-1
NOTE 2 Typical fuels meeting this specification are certain solvent fractions sometimes referred to as commercial
heptane.
K.3 Test procedure
K.3.1 Test conditions
Carry out the test under the following conditions:
a) airtemperature (15±5)°C;
b) fueltemperature (17,5±2,5)°C;
c) foam solution temperature (17,5 ± 2,5) °C.
K.3.2 Set up
Position the foam nozzle horizontally with the by-pass holes in the adjustable collar facing downwards at a height of (150 ± 5) mm above the rim of the fire tray (see Figure K.2).
Prepare the foam solution following the recommendations of the supplier for concentration, maximum premix time, compatibility with test equipment, avoiding contamination by other types of foam, etc.