PETROL QUALITY.

New Zealand Herald, Volume LXIII, Issue 19412, 21 August 1926, Page 10 (Supplement)

PETROL QUALITY.

STANDARD TESTS URGED.

The necessity for safeguarding tho quality of petro" is exercising the North Island Motor Union. Regulations which will empower inspectors to test tho suppiy from pumps are sought. Ihe Auckland Automobile Association has made several suggestions for the compulsory grading of petrol. At tho meeting last week several members pointed out that tho term, " motor spirit" was generally accepted as applicable to tho better grades of petrol. When a motorist bought " motor spirit" from a pump ho was entitled to assvrne that he was securing high quality benzine. It was remarked that the Government insisted on a certain quality spirit for use in departmental vehicles. There were a number of pumps which carried no brand, and the motorist who had preferences could not dispute with tne vendor although it might be suspected that the brand was changed to suit tho occasion. There is no doubt that there are a few unscrupulous vendors who nandlo unbranded petrol to the motorists' disadvantage. Poor quality petrol is a bad investment. Motorists who find that the carburetter suffers from corrosion should euspect the petrol. Motor spirits which have not been completely refined often contain free acids which attack brass and copper, causing blackening at first and later more troublesome corrosion. It is not uncommon to find tho gauze Strainers eaten with holes. Impure petrol will attack tho brass gauze at the tank connection, at the vacuum tank strainer and at the carburetter strainer. A brand of petrol recently sold in Auckland contained so much freo acid that there wore innumerable instances of tho floats in the vacuum tanks being perforated and rendered inoperative. With a view to proving the lack of uniformity in even first-grade spirit, tests were taken in Christchurch. They showed that the specific gravity of first-grade brands varied from 605 to 65 (Beaume), 1 while second grades ranged from 55 to 60. Although second-gr:.ide petrol is usually heavy, the specific gravity of a spirit is not the sole indication of its quality. A heavy spirit may actually provide more power under certain conditions. Method ol Distillation. Three-o ; iiarters of the world's supply of motor spirit is drawn from crude oils produced in the United States. Motor spirit is produced by the fractional distillation of crude petroleum. In this process the oil is gradually heated up and the distillates obtained at various temperatures are collected, After the petrol has been obtained, other products such as kerosene, gas oil and lubricating oil may be extracted, while the residues of distillation may be employed for furnace oils and asphalt manufacture.

In addition to the direct method of removing tho petrol by distillation, it ' is also possible to prepare petrol from the heavier fractions such as kerosene and gas oil, by subjecting them to heat and pressure arid bringing about a chemical change. This is known as tho cracking process. The petrol, whether produced by distillation or cracking, is then treated by agitation with sulphuric acid. This treatment results in the removal of a tarry substance. The spirit i 3 then treated with caustic soda to remove the Bcid. Tho quality of the spirit is affected by its distillation range, and a petrol collected over a wide range may contain a large proportion of substances, of n high boiling point, while spirit gathered at low temperatures will be more volatile. The quality of a spirit must be guaged ■with reference to its distillation range, the aromatic content, freedom from corrosive tendencies and the odour and colour. Fuals with a low aromatic content are prone to detonate or cause pinking in a modern high compression engine. Common i alcohol contains from 5 to 6 per cent of water, and is not soluble in motor spirit*. When this water is removed, alcohol may be added to petrol to produce a non-pinking fuel. Benzole is also used overseas to provide antidetonating fuels. Benzole consists of the lightest fraction of coal-tar suitably purified. . A gallon of old-fashioned and very volatile petrol weighs about 71b., ordinary petrol 7'Jlb. to 7|ib., benzole mixtures, 7flb. to 81b., and cure benzole Bflb. Irrespective of specific gravity, a good spirit must contain a fairiy high proportion of aromatic hydrocarbons or other non-pinking constituents. It must also bo free from corrosive sulphur compounds. Popular petrols have gravities of from .741 to .744. Aviation spirits may be as low as .730, and special petrols as low as .684. Fuel Research. Scientists are achieving considerable success with research connected with coal oil fuels and alcohol from palms. The carbonisation of one ton of coal produces 5600 cubic feet of ga3, 19 gallons of heavy liquid fuel, and 2 gallons of benzole motor spirit. In addition, there is a residue of 14ewt. of coke. The German Berius process has produced from 30 to 50 per cent, of liquid fuel from one ton of coal. The yield of motor spirit is sot down at 10 gallons per ton, and tho heavy oils at 100 gallons. A recent test of Lancashire coal showed a yield of 130 gallons of liquid per ton. Through the necessity forced upon them by the war, Germany made considerable advance in tho exploitation of alcohol. At present a mixture of 70 per cent, alcohol and 30 per cent, benzine is sold in Europo under the imme of Manopolin. Alcohol fuels are being successfully produced in South Africa and Borneo. Australia is said to abound in vegetation which would yield profitable nlcohol fuels. A. company with a capital of £1,000,000 is in conrse of formation in Queenslar'' It is proposed to erect distilleri" at Cairns and at Townsville. Th«* bairns distillery should have an »atput of 1,000,000 gallons of spirit, p* Annum.