BOB JOHNSON
Choose your extinguisher carefully
The combination of a group of children, two types of fire extinguisher and a 13th century
church led to a £300,000 bill for clean-up and restoration.
It has been recognised for some time that correctly
placed fire extinguishers, combined with staff
trained
in their use, are a useful first line of defence
against a
fire in its early stages. If used correctly, they can
prevent
a fire getting out of control and causing untold
damage
to a property. It may therefore seem strange that a
fire
extinguisher intended to help prevent damage can
itself cause considerable harm to both buildings and
their contents. An incident in a Grade I 13th century
church clearly demonstrated the importance of care-
fully considering the suitability and positioning of
dry
powder extinguishers in heritage buildings.
Those who have never seen a dry powder extin-
guisher discharged may be surprised by the quantity
and spread of the powder. While hopefully putting out
a fire, the discharge creates a vast cloud of
particles
which can take days to settle and clear up. This can
result in areas such as kitchens and offices becoming
temporarily unusable, food stuff being contaminated
and expensive office equipment requiring replacement.
What is less well known is that if the powder
particles
become damp they may form an acidic paste that can
corrode and degrade stonework, metalwork, fabrics
and other materials.
In the case of the 13th century church, a group of
children deliberately discharged both dry powder and
water extinguishers in the church. The ‘damp’
particles
from the dry powder extinguisher settled on virtually
every surface throughout the building, including the
organ, roof beams and stained glass. Scientific
testing
established that the resultant paste was corrosive,
requiring all surfaces to be cleaned to avoid damage.
Clean-up operations started with the extensive
vacuuming of the powder discharge by professional
cleaning services. Restoration of the property
followed.
It included conservation specialists for such areas
of
the historic property as the pipe work, the
electrical
circuits of the organ, the painted chancel ceiling,
the
chancel screen and the pulpit. High-level surfaces
throughout the church had to be cleaned to prevent
future deposition of powder on to the area below,
and damage to the stonework at high level. The
eventual clean-up and restoration bill for the
property
was £300,000.
Even when discharged to tackle a fire, there is still
a
strong likelihood that the powder from a dry powder
extinguisher will become damp and cause further
damage to the property. As a result of this incident,
Ecclesiastical Insurance is advising customers to
review the type and location of extinguishers on
their
premises. Should they find that dry powder is present
in areas where there are historic items or fabric,
serious
consideration should be given to replacing these with
different extinguishers. The same considerations
apply
in areas with electrical equipment, such as
computers,
which are likely to be adversely affected by the
powder.
Fortunately, alternative extinguishers (such as car-
bon dioxide or AFFF (aqueous film forming foam)
are readily available in the large majority of cases.
These are potentially less hazardous in a historic
environment, but will still deal effectively with a
fire in
its early stages.
Bob Johnson
is technical
survey manager
for Ecclesiastical
Insurance.
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