The Purification of Fue and Lubricating Oils
Page 60
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ANY liquid employed as a fuel for internal-combustion engines must be free from foreign matter or it will cause trouble with the carburetter or, in the case of the oil engine, with the fuel-injection pump.
. One of the most interesting new products of Tecalemit, Ltd., Great West Road, Brentford, Middlesex, is a special filter for purifying oil fuel for compression-ignition engines. The external casing is a casting which can vary in design, according to the position which it will have to occupy on the dash or power unit. Forming part of the body of certain patterns is a simple hand pump ; this is provided in order that, should the main tank have been allowed to run dry, fuel can be drawn through from the tank to the injection pump without the need for prolonged cranking or continuous use of the starter motor. On the top of the body is an air-release cock, The actual filtering element consists of a felt-covered sleeve ; the base is of stout galvanized wire and, in section, is star-shaped. The felt is specially treated to make it free from fluff. It is stated that this element will pass 30 gallons per hour, the liquid being at about 70 degrees F., and of the usual gas oil or Diesel oil viscosity. This quantity is many times in excess of normal requirements, so that there is ample margin to allow the filter to be used even in a neglected condition. The element is retained by a detachable cover plate, below which is a spring-loaded disc that is free to adopt any desired position to ensure a seal at both ends of the sleeve.
The oil cleaner and cooler used for lubricant embodies a somewhat similar system. The body is usually of a type specially designed to suit the crankcase casting; it is a standard fitment made by the engine manufacturer. A detachable cover is used to locate a star-section element
A by-pass, of the piston or ball-valve type, is provided which short-circuits the element in the event of it creating a resistance in excess of 10 lb. per sq. in. This prevents the risk of damage to the engine if the oil be excessively thick when starting from cold or if the filter be allowed to become very dirty. The loss of pressure set up by a dirty sleeve does not exceed 10 lb. per sq. in. It is recommended that the element be rinsed in petrol every 3,000 miles and replaced after 20,0® miles. A drain plug can be provided in the easing if specified. In the case of a cleaner with a finned casing, mounted in the slipstream of the .fan, the cooling effect is 7 degrees C.
The Tecalemit filter is now being adopted as standard by many of the large commercial motor Manufacturers; it has had two years' extensive trial. Three sizes are made, capable of dealing with 200, 400 or 500 gallons per hour.
This form of cleaner is of particular value in the case of compression-ignition engines Which are aptto suffer considerably from carbonized oil. This is commonly due to incomplete combustion and the high compressions used, some of the fractions of fuel reaching the sump in sufficiently large quantities to give rise to this trouble. The Tecalemit cleaner collects the whole of the non-soluble foreign matter and a large proportion of the colloidal carbon.