CARBON BLACK USED IN NEW
ANTI-STATIC FLOORING
P ROVISION of suitable flooring
material for areas in which the possibility of electro-static sparking could be hazardous is a problem of extreme importance. An investiga- tion carried out in England on anaesthetic explosions showed that out of 36 cases examined. 14 had definitely been caused by electro- static sparking. (Report of a work. ing party on Anaesthetic Explosions: H.M.S.O. 1956).
Areas where inflammable or explo- sive gases, liquids or solids are handled or used. such as operating theatres or anaesthetising rooms in hospitals require special measures in flooring. It is necessary to ensure the safe passage of static electricity from persons. trolleys and other objects which are required. of course, to have effective electrical contact with the floor surface by means of conductive footwear or
castors etc.
The finished floor should have a low electrical resistance but. due to the danger of electric shock associat- ed with equipment connected to mains electricity. the resistance of anti-static flooring must not be too low and must be kept strictly within limits laid down by the various technical memoranda and relevant publications (Hospital Technical Memorandurn No. 2. Anti-static Precautions Flooring in Anaesthe- tising Areas, H.M.S.Ö. June 1962).
Existing anti-static or conductive floorings are confined to either:— (a) Terrazzo the laying of which demands a great deal of care and supervision if the desired imperforate finish is to
be achieved, with no possibility of any cracks appearing at a later date.
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Also, the electrical resistance is difficult to control. giving rise to wide variations in value.
th) P.V.C. rubber от Linoleum. Anti-static or conductive pre- sentations of these materials to date rely upon the introduction of carbon black during manu- facture, in a manner which gives a black or predominently black finish. Additionally, the type of manufacture employed necessitates critical proportions of carbon black if the correct electrical resistance values are to be achieved.
Most existing conductive floorings require the use of a metal earthing system, either in the form of wire netting or copper strips which mean added complication and care achieving the desired result.
in
An entirely new principle in the production of conductive flooring. for which patent application has been made, has been developed by the Marley Tile Co. (Hong Kong agents Dreyer and Co. Ltd.)
This anti-static flooring incor- porates carbon black to provide the necessary conductivity, but the prin ciple involved allows a wide margin in the quantity used. Additionally. the black colour is not apparent. which means freedom in
in colour choice and presentation.
The flooring can be manufactured to achieve a wide range of conduc- tivity or resistance and whilst pre- sent production meets British Minis- try of Health requirements for operat-
T
ing theatres and anaesthetising areas, electrical specifications for anti-static flooring for overseas hospitals are also satisfied.
With this flooring the necessary conductivity is achieved without the use of any metal earthing system, such as wire netting or copper strips. thereby simplifying the actual floor laying.
The flooring is available in tile form 18" x 18" at 80, 1000 ins. thickness and three standard colour patterns.
Application is carried out in the usual floor-tiling method on the usual sand 'cement screed, using a special conductive adhesive. which is known as Marley Adhesive No. 26. The screeding specification should be as laid down for P.V.C. tiling generally
re-cut
Tiles are laid to buttjoint and all joints are
and welded by machine with seaming strips after laying. This prevents possibilities of direct electrical shorting by water seepage between the tile during washing maintenance and allows no crevices where the build-up of dirt and bacteria may occur. Direct con- tact of the adhesive with earthed objects, such as water pipes, should be avoided. It is recommended that an insulating collar he put around pipes and conduits to prevent such
contact.
THE HONG KONG & FAR EAST BUILDER-VOLUME 19, NUMBER 2
Page 120Page 121
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