Page 72 - Studio International - May June 1975

Engineering Systems for Galleries

James R. Briggs and Peter Smith

All material objects deteriorate possible to include windows provided level track system has many uses.
because they comprise various these are located and constructed
chemical components which may realizing the implications of natural Fire Control
react with other components and light variations, of both level and colour We put this as the second priority but
with the components of their temperature, and its high ultra-violet consider it of equal importance to lighting
environment. The reaction or content. The latter may be filtered out. because a destroyed object is worthless
deterioration rate depends on the The filter should be in a permanent form and the safety of people must be
chemical components involved and that will not deteriorate with time, and paramount. The key to successful fire
the quantity and quality of light and the window size and location need to be prevention is to start with a low fire
heat energy present. If excessive selected and controlled so that risk, by excluding as much easily
deterioration is to be avoided then maximum internal illumination levels are combustible material as possible, and
it can be essential to control the not exceeded and some form of automatic then arranging for detection at the
environment's chemical blinds or shutters may be needed. It must earliest possible moment. This is best
components, such as sulphur dioxide also be realized that windows are a great done by an automatic detector system
and water vapour, which may react source of heat gain and loss and lead to a supplemented by the ordinary 'break
with the object, both chemically and greater need for air conditioning or glass' call points — which may be
physically, and the light and heat heating as well as being prone to statutorily required anyway. Detection
energy levels, particularly light. condensation and, where not sealed, to must of course be immediately and
Also it is essential to have the lowest the ingress of dirt. In any event an effectively indicated and, when people are
possible fire risk. artificial lighting system will be needed present, a general alarm given. A fire bell
In practical terms the factors and luminaires designed for display are system is probably adequate when staff
that need to be considered are: available in standard ranges, but can also are present but direct indication to a
the lighting (both natural and be specially made. Suitable light sources central building point and to the Fire
artificial); fire control (ie are fluorescent, tungsten filament and Brigade is much to be preferred and, also,
detection, indication, alarm and tungsten halogen lamps. Mercury and perhaps to a commercial control centre
fighting); air condition (ie sodium lamps are not satisfactory because that would relay a signal in the event of a
temperature, humidity and air of their colour effects. Fluorescent lighting malfunction. To avoid malfunctions at
purity); security; communications with 150o and 1800 nun tubes should be times of emergency, as far as possible, the
and emergency energy supply — and used as much as possible, because the wiring system should be arranged to be of
for us this is the order of priority. energy consumption is relatively low, and the 'fail safe' type in which any departure
For a new building the cost of when used with correctly matched tubes, from normal gives an indication of a fault
providing engineering systems to shielded with a diffuser to absorb UV condition and thus be proof against
give ideal protection, for all these and to avoid glare, can supplement equipment failure and interference.
factors, can easily exceed 40% of the natural lighting very well, as has been Once a fire does start it is essential to
total building cost and it is, therefore, done at the National and Hayward have, immediately to hand, equipment
necessary carefully to consider the Galleries in London. But, particularly that will tackle the fire in the best way to
degree of protection justified for where there is no natural lighting, it is reduce to the minimum damage caused
each factor, and we have tried in this difficult to use fluorescent lighting in an by the fighting agent. This can range
brief paper to set out some of the aesthically pleasing way at the lower from hand-held extinguishers to the
main parameters. illumination levels. Where modelling is final resort of the main water hoses of
important, and for special effects, the the Brigade, and, between these two
Lighting less efficient tungsten filament lamp is extremes, there are; first aid hose reels
Since art is nothing if not seen, probably best, because it is possible to (which may deliver water or gas); local
lighting is, for us, of primary use different beam angles and projection gas flooding; water sprinklers and
importance and is needed both to to obtain precise particular effects — drenchers and building gas flooding
illuminate exhibits and the public ways although it is helpful to get computer systems. It is our opinion that things
through the building — care is needed assistance with the calculations. have gone sadly wrong if the Brigade
to prevent conflict between the two Dimming can be used for final need to resort to their main hoses and
functions and particularly to avoid adjustment and it is worth knowing that that the building equipment should
pools of bright light against a dark back- the lamp life can be increased from the include `BCF' gas hand-held
ground. Unfortunately the ideal levels normal z000 hours up to 800o hours with extinguishers as the best method of
of light for visual comfort can be very a io%voltage reduction. Dimmers initial attack backed up by water hose
damaging, particularly when there is an should therefore be of the Thyristor reels, since these are continuous and
ultra-violet content and the effects type and the electrical system must be carefully used do not cause more damage
depend on the illumination levels, time arranged to accept the fourteen times than they prevent. Perhaps other than in
of exposure and the chemical steady-state current that can occur on public areas, CO2 gas flooding seems to
composition of the object. Fabrics and switch-on and may damage the us to be highly desirable as it can be set
paper, particularly with watercolour dimmers. Voltage reduction does cause to be automatic when there are no staff
pigments, are very sensitive and for an increase of the red content of the present, when statistically, the time most
these the illumination levels should not light but this is not often significant. fires start.
exceed 150 lux (50 for watercolours etc.) Tungsten halogen lamps cannot be
with no ultra-violet component. For dimmed and need careful installation to Air condition
maximum protection light should be achieve a 2000 hour life but its small size The air temperature, humidity and
excluded as much as possible and, in and high quality light-output make it purity all have an effect on all objects, but
extreme cases, time limiting may be invaluable for accurate focusing and some objects are more sensitive than
needed ie 'push button to display' projection over long distances. Below others, and, from our study of the
techniques. Most people would agree 30o watts the supply voltage must be literature, we have concluded that it is
that artificial lighting is a poor reduced by a transformer. Flexibility of change of the moisture content that is
substitute for natural lighting and it is lighting is the main need and a high the most damaging, and this is constant
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