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45
Industrial hygiene, safety, etc.
Mention has been made in preceding sections of some of the matters in which advice
was given or action taken to avoid hazards of various kinds. Other cases which can be
instanced under this general heading were :
Mercury discharge lamps designed to sterilise and deodorise air were given a
practical trial in occupied rooms, measurements being made to ensure that the production
of ozone and ultra-violet light was kept within appropriate limits.
A report was made on the properties of trichlorethylene with reference to its use as
a domestic dry cleaning agent.
Precautionary recommendations were made for the siting of a building in which
methyl bromide and hydrogen cyanide were used as fumigants.
Analysis of special tools, to be used in excavating ground contaminated with petrol,
confirmed that they were of a suitable non-sparking alloy of beryllium-copper. In
another similar case, where a steel auger had to be used, a non-inflammable atmosphere
was maintained in the bore hole by repeated addition of small pieces of solid carbon
dioxide.
The use of electrically conductive rubber for petrol pump hose was considered, it
being a matter of importance for static electric charges to be discharged without a spark
passing which could ignite petrol vapour. Practical trials were made to investigate the
durability of the material.
Metals
As in previous years, regular analyses were made of the various grades of solder
purchased by the Supplies Department. Compliance with the appropriate requirements
of British Standard 219 was, on the whole, better than in previous years. Other fairly
regular examinations made were those to determine the quality of chromium and other
electro-plating on various fittings. Advice was given on many particular problems of
combating corrosion, especially of iron and steel. Interesting examples of work in this
section were :
The cause of corrosion of an aluminium flush pipe was found to be the ability
of the water to take up traces of copper from other parts of the system and hence to
form minute centres of galvanic attack where this copper was desposited. (It cannot
be over-emphasised that mixed-metal' water systems—e.g., zinc tanks with copper
piping—should be avoided.)
For reasons similar to the above, consideration had to be given to avoiding the
possible corrosive attack on the aluminium Eros statue in Piccadilly Circus from the
recirculating water which falls from the fountain into bronze basins.
Grades of hot applied bitumen were tested after application as ¼ inch thick layers
inside sections of iron piping to see if satisfactory protection of the pipe would be
afforded against the action of sewage liquors. It was found that both grades submitted
gradually flowed at the temperatures likely to be met.
Further consideration was given to particular cases of metal corrosion-protection,
e.g., by zinc-rich paints, metallic lead paints, flame-sprayed metal, sacrificial cathodic
protection, etc.
Lengths of electrical conduit were examined to determine whether it was the
quality of it which was responsible for difficulties encountered in bending. Poor
technique and not quality was found to be the cause.
Miscellaneous
Advice was given on a variety of other matters not included in the previous sections
of this report. The following may be mentioned as examples :
Samples of hair lotions from hairdressers' establishments were examined and
found to consist of (i) sulphur, methylated spirit and green dye; and (ii) methylated
spirit containing about 10 per cent. of castor oil. As these preparations were sold at