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Safety in sewers
Regular examination of inflammable gas detector lamps of the expanding metal spiral
type and those based on selective diffusion is made to ensure that all lamps are in good
order and advice is given as required on the use of self-contained oxygen respirators.
Experiments have continued on methods of improving sewer ventilation.
Housing
The work done by the branch for this service covers a wide field and is of considerable
economic importance. Thus, in the particular case of paint and surface coatings for
houses, flats, schools, bridges, etc., the annual expenditure of the Council on materials
and the labour charge for their application amounts to approximately Jj\ million.
By ensuring that materials of suitable quality are used, the savings in maintenance
must greatly exceed the cost of an advisory service. The work in this section is reviewed
regularly by an inter-departmental paint committee, on which all the departments
using or concerned with paint are represented.
Approved lists of manufacturers brands of paint are maintained, and during the
year 88 new brands were approved after test while a further 88 were found not to be
of the quality required. Some of the more frequent causes of rejection were :—low
opacity, poor surface finish or hardness, and presence in exterior paints of lithopone or
excessive amounts of chalk.
In addition to the laboratory examination of materials, visits were made to sites to
investigate defects arising from such causes as unsatisfactory preparation of surfaces or
manner of application of paint. Advice on many aspects of decorating has been made
available to all user departments. This has included assistance in questions of colour
matching and the establishment of standards, and the recommendations for the painting
of a wide variety of materials under various adverse conditions.
Increased demands are being made on the facilities provided by the branch for the
examination of building materials. The range of materials received for assessment of
quality or investigation of possible faults included floorings, floor sealers and polishes,
plasters, light alloys and plastic building materials, fire retardents, concrete, slates,
asphalte and bitumen felts. In addition to laboratory tests, small scale practical trials
under normal conditions of use are frequently made, and sometimes accelerated
weathering tests are employed to assess the value of articles intended for external use.
Wherever applicable reference is made to British Standard Specifications in assessing
the quality of a product. Officers of the branch visited many sites to examine and advise
on problems at first hand and have thus maintained close contact with the practical
difficulties sometimes involved in the adoption of new methods and materials.
Examination was made of clays and ground waters from building sites. The importance
of tests on these samples has increased with the frequent use of high blocks of
flats in housing schemes. The deep concrete foundations of these flats may be in contact
with moist soil or ground water where sulphates normally present in London clay can
weaken Portland cement concrete. Estimation of the sulphate content in the soil enables
recommendations to be given as to the appropriate cement to use to resist aggressive
attack by sulphate in excessive concentrations.
Air pollution
The Council has for many years co-operated with the Department of Scientific and
Industrial Research in investigating the incidence of air pollution. Regular observations
are made at 20 sites, which include seven of the parks, five sites near hospitals, both
Council sewage outfall works, Kew Observatory, and the grounds of King George V
Hospital at Godalming. Standard types of instrument are used and at a few of the sites
comparative records are available for a period of 35 years.
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