IS A TESTING LABORATORY NEEDED IN HONGKONG
MEMBERS OF THE ENGINEERING SOCIETY DISCUSS AN IMPORTANT PROBLEM
At the regular monthly meeting of the Engineering Society of Hong Kong which was held at the Hong Kong Hotel on 5th October, 1949, Dr. S. Y. King of Hong Kong University read the following very interesting paper on the need for a public material testing laboratory in Hong Kong.
It is well known that a sound engineering design must be The accompanied by the use of the right kind of materials, modern industrial method of mass production would not have been possible but for the use of uniform raw materials. Specifications on different engineering materials have thus been set up in various countries. e.g. those by the British Standard Institution, the American Society of Testing Materials etc. Material testing laboratories have also been established to check the suitability of materials used.
It is interesting to note that material testing laboratories have been in existence for nearly a century. As early as 1856, when the first Atlantic submarine cable was being laid, Lord Kelvin found from his scientific investigations that the electrical resistance and capacity of this long cable should be low before telegrams could be successfully transmitted.
The importance of resistance led Kelvin to investigate the conduc- tivity of copper. To his surprise, the conductivity of commer- cial copper varied enormously and a small percentage of impurity could reduce conductivity by 30 or 40 percent. Unless a clause specifying the conductivity of copper was included in the specifications for cable contracts, the cable would not function properly. Kelvin's investigation led to the foundation of the first industrial laboratory for testing materials. It also had great influence on the standardization of engineering materials.
It is true that Hongkong is mainly a port of trade and not an industrial centre. Our industry here is negligibly small in comparison with that of Britain or U.S.A. From the economical point of view, there is certainly no justification of having in this Colony a laboratory as elaborate as the National Physical Laboratory in Britain. The question before us to-day therefore, is that do we need a laboratory on a smaller scale in Hongkong? Before we can answer this question, it is necessary to make a general survey of Hongkong's existing industries. We have here local industries in ship building, ship repairing, and a wide range of light industries, the main products of which are textiles, rubber goods, torches, plastics, cigarettes, matches, tinned goods, glass ware, paint and builders hardware such as locks, hinges, nails, screws etc. New industries introduced during last year include the manufacture of textile machinery and electric irons. In our building pro- gramme, there is also a great demand for building materials such as steel, brick, timber and cement. For the moment, we are locally producing cement at about 4000 tons per month. With the installation of a tunnel kiln, brick production has also been increased. Regarding building steel, one Hongkong firm has successfully evolved a process for rolling steel bars from old local ship scrap and improvised the necessary machinery.
Now let us turn our attention to the electric supply. If I am not mistaken, the installed capacity of electric power in Hongkong and Kowloon amounts to something like 75,000 KW. Upon the completion of a new 15,000 KW. turbo-set being installed by the Hongkong Electric Co., it will increase to 90,000 KW. This industrial and domestic use of electricity obviously necessitates large suppies of electric wirings, hittings and
meters.
In brief, Hongkong is now daily consuming tons of materials used in all branches of engineering.
Many testing laboratories have already been in existence here in different institutions and industrial establishments. In testing chemical properties of materials we have laboratories such as the Government's Chemistry Laboratory, the University Chemistry laboratory etc. In testing mechanical strength of materials, there are laboratories run by the Taikoo Docks, the Kowloon Docks, the University etc. However, are the facilities afforded by these laboratories sufficient to meet the require- ments of material testing in Hongkong to-day?
A public material testing laboratory has certain advan- tages over private ones run by individual firms. Firstly, no private firm can afford to spend money on its laboratory equipments other than those which are absolutely essential to their works. Certain testing equipments may be useful to many private firms in common, but are usually too expensive for one individual firm to install. Under these circumstances, it may be advisable for those firms concerned to invest jointly in these expensive equipments. Secondly it is more economical to run a public laboratory than to run several small private ones. In this way, we can not only avoid the unnecessary cost of repetitions in certain equipments, but also afturd to invite experts to supervise certain specialized experiments, such as soil analysis or the tests on dielectric strength of electrical materials. Lastly, a public laboratory is often more convenient to small Arms which possess no testing facilities of their own.
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While considering the necessity of establishing a public tesling laboratory in Hongkong, we must at the same time study the testing facilities which this laboratory should provide. The scope of work of this laboratory may be divided into five main branches and it is up to our members of the Society to decide what tests are essential to their practical works and what are not essential or not justified economically The five to be provided in this non-industrialised Colony. branches of tests in the laboratory are:
I. Electrical tests, including the dielectric testing of insulating materials and the testing of general electrical properties.
II. Chemical tests, including the testing of fuels such as coal and oil and the general chemical analysis of materials.
III. Mechanical tests on strength of materials. IV. Soil mechanics.
V. Miscellaneous tests which include the testing of refractory materials, fire-proof materials, lubricating oils, heat insulating materials etc.
In addition, there may be other important tests which have not been included in the above list.
With regard to the electrical tests, emphasis must be laid upon dielectric testing of insulating materials. All electrical engineers are well aware of the fact that the insulating properties of certain dielectrics deteriorate rapidly at high
ambient temperature and humidity. In a sea-side location such as Hongkong, the effect of salt-laden air on insulating materials may also be detrimental at high temperatures. The temperature in Hongkong sometimes exceeds 95° F. In Spring and Summer the humidity is persistently high, at times exceed- ing 95%. Under such conditions, it is clear that insulating materials suitable for use in Britain may not prove equally successful in our local climate. Electrical wires or cables from abroad should be tested for their insulating qualities not only on their arrival but also after having been exposed to Hong- kong's atmosphere for some months or even years. These tests may involve the use of the Schering Bridge and other related instruments. Apart from the testing of dielectric properties, there should also be over-voltage tests and electrical resistivity tests which determine the leakage currents flowing through the insulating materials. All the above tests should be conducted while the insulating materials are being exposed to our local climate and testing records should be taken from time to time during this long period of exposure. From these tests, we will then be able to determine what insulating materials are best suited to Hongkong's climate.
A chemical testing laboratory is generally meant to handle the chemical analysis of different materials. To engineers, it is necessary to know not merely the chemical composition of materials, but also the effect of ambient influences on materials, such as corrosive vapours in industrial areas and salt-laden air in coastal districts. Protective media such as paints, varnishes, enamels and lacquers should undergo a thorough investigation as to their protective values under normal ambient conditions. There is yet another important test that concerns most engineers in power fields, i.e. the testing of fuels, including oil and coal. Taking oil for example, it is well known that a particular Diesel engine should always run with oil of appro- priate grade. In other words, the laboratory should provide facilities for testing oils according to, say, B. S. Specification 209, 1947, which includes the determination of cetane number, viscocity, flash point, calorific value and other items.
Mechanical tests on strength of materials generally consist of testing for tensile strength, hardness, impact, torsion, compression and transverse strength. For testing cement, a special cement testing laboratory is necessary. To study the fatigue of metals under different stresses, fatigue testing machines must be provided. It is important, in conducting these tests, that all the testing machines are properly calibrated. Gauges should be frequently checked by gauge testing apparatus and tensile or compressive testing machines by tensile or compressive standardising boxes.
When metals are subjected to both tensile stresses and elevated temperatures, their creeping properties must also be determined. By the addition of an electric furnace to а suitable tensile testing machine, we can determine the influence of high temperature upon the properties of material subjected to tensile stresses. The time taken to break a test bar at a constant elevated temperature and at a constant load can be determined by special apparatus which is designed to hold the load on a test piece for any desired length of time irrespective of any deformation of the test specimen, The modulus of elasticity of a bar at elevated temperature can be found by a special mirror extensometer.
The subject of soil mechanics has received considerable attention in civil engineering circles. Soil, being the natural material on which every structure is supported, must be investigated as a material with equal importance to steel, concrete or timber, which it has to carry. A properly designed structure without an adequate foundation would certainly mean failure. Before laying the foundation on a particular