Click on Fire Test thumbnails below for enlarged views
Following the success of tests carried out at Boreham Wood prior to the LPC being taken over, a second, more exhaustive series of fire tests on Scotch Mist® was commissioned. Fire testing was conducted against selected approval fires for gaseous extinguishing systems (see Fire Tests at Boreham Wood), including some of the baffled fires used within the test standard LPS 1230. Local application and total flood tests were carried out on each of the test fire scenarios, each test lasting for only ten minutes.
The enclosure used for the evaluation of
extinguishing systems is a purpose built structure having internal dimensions
of 8.1 metres long by 4.1 metres wide and 3.6 metres high. The internal
volume is approximately 120 cubic metres.
Forced ventilation is
available to ensure that test fires are fully ventilated and burn with an
upright plume, whilst there is a high level controllable extraction capable of
extracting volumetric flows of up to 9 cubic metres per second, for the removal
and treatment of smoke and hot gases. An over-pressure device is fitted
in a panel adjacent to the door of the test enclosure and an over-pressure
protection vent, weighted to open at 600 Pascals, located in the
ceiling.
The large wood crib fire (see Fire Tests at Boreham
Wood) is particularly difficult to extinguish due to its capacity for deep
seated burning but for each of the total flood tests, the fire was controlled
for the period of the test and for local application system designs, all wood
crib fires were successfully extinguished, with no reignition occurring when
the Scotch Mist® was turned off after the
ten minute test period.
The PVC
crib fire (see Fire Tests at Boreham Wood) has been re-designed since the first
series of tests and is now an even more stringent test for gaseous
extinguishing agents. Some baffled fire tests were carried out in order to
test the ability of Scotch Mist® to
tackle shielded fires, such as may be found within an EDP environment, but none
of the baffled test fires were extinguished, although there was evidence of
fire control during system operation. All unbaffled test fires were
successfully extinguished within the 10 minutes of water mist operation,
whether local application or total flood design.
Two sizes of pan fires are used
for the heptane test fires, a small 300mm diameter pan, used for the original
approval fires for gaseous extinguishing systems (see Fire Tests at Boreham
Wood), and a large 600mm square pan, used for approval fires for gaseous
extinguishing systems when tested to ISO 14520 under the standard LPS
1230.
All heptane pan fires were
successfully extinguished by Scotch Mist®
with the local application design and were controlled with the total flood
design.
But of most significance was the heptane spray fire,
carried out under a number of varying conditions. The heptane spray fire was
tested using large metallic obstructions that became a source of reignition
when hot, and various tests were carried out under ventilated and
non-ventilated conditions. With the exception of a single test carried
out at low pressure, all spray fires were extinguished.