The following recommendations have been prepared for the use of those already using oil fuel for their steam boilers, by The Manchester Steam Users Association.

A full supply of air to the burners must be maintained, otherwise partially burnt fuel passes into the flues, where it may re-ignite and cause serious damage. In one case which recently came under our notice the " secondary " flame did damage in a boiler side flue, and in another instance it occurred in an economiser flue. Owing to the long flame, and also to the possibility of this re-ignition of the waste gases after partial burning, the shell plates may be exposed to high gas temperature, therefore, when burning oil, the scaling of shell plates is as important as that of furnace plates.

In using oil in horizontal cylindrical furnaces with the grates removed, the lower parts become etfective heating surface. These parts are commonly neglected as regards scale, but require the same attention as other parts and should be kept quite clean at the waterside when exposed to heat.

The oil flame should not strike the furnace plates directly, as, apart from any risk of overheating, the flame is thereby cooled and combustion checked, result ing in black smoke and waste of fuel.

Seams should be protected from the direct impact of flame.

It is not necessary to line the furnaces with brickwork if the plates are clean at the water-side, but a screen or bridge of brickwork for the flames to play upon is a great aid to combustion. If the furnaces are lined the flames do not part with their heat at these parts, and the furnace tubes or combustion chamber beyond the brickwork lining have to take up excess heat. In vertical boilers the flame should be inclined downwards on to brickwork, care being taken to protect the base seam. Water-tube boilers with large combustion spaces lend themselves well to oil firing, but here also care should be taken to keep the flame from striking directly on the water tubes, drums and headers.

Flue gas explosions are more apt to occur with oil fuel than with coal or coke, and precautions are necessary in order to avoid them.

Unburnt or partially burnt oil in the flues is liable to explode.

Volumes of unburnt gas may pass into the flues if, for instance, a burner fails temporarily and is not at once shut off, or relighted. Again, undue restriction of air supply to the burners will result in filling the flues with partially burnt gas.

Both these conditions are dangerous, and we recommend that the following precautions be observed in order to avoid gas explosions :-

The flames at the burners should be under constant observation. Should a flame be accidentally extinguished it should at once be relighted, or the oil shut off. If the burner has been discharging unburnt oil for an appreciable time the oil must be at once shut off, and time allowed for the flues to clear before relighting.

The dampers should never be closed when burning oil. Steam output should be regulated only by the oil, steam, and air supply at the burners.

Under proper condi tions there should be a light grey smoke from the chimney ; dense black smoke indicates incomplete combustion, and white smoke shows that excessive air is being used.

Using oil and coal or coke together is not altogether desirable, although very convenient when the available coal supply is inadequate. In ordinary furnaces, such as in the Lancashire boiler, the combustion space above the grate is too small for the satisfactory combustion of oil fuel, and it is more satisfactory to burn coal only in one furnace, and oil only in the other.

Oil leakages are, of course, very objectionable, and may be dangerous, especially if the oil finds its wav into boiler flues. It will vaporise there and very likely explode.

Fuel oil in the open is not particularly dangerous, as it has to be finely divided before it will burn readily. But vapour from heated oil is another matter, and members will be well advised to adhere to their Fire Insurance Companies' instructions as to necessary precautions.

Oil Lubricating For Diesel Engine Air Compressors

At a recent meeting of the Diesel Engine Users' Association, the question of the proper kind of oil for use in Diesel engine air compressors was discussed, and the following recommendations were made :-

The lubricating oil used in the air compressor should be an oil of the highest grade obtainable, and must be used only in the smallest practicable quantity.

The following properties are necessary in all lubricating oils for Diesel engine compressors.

(1) ;The oil should be entirely free from suspended particles of water.

(2) ;The oil must be entirely free from sand or other inorganic material. No mechanical impurities must be visible in the oil when it is viewed by holding a sample in a glass vessel against a light.

(3) ;The oil must be entirely free from inorganic acids.

(4) ;Oils should not be lower in viscosity than 300 seconds Redwood at 70 degs. Fah., nor higher in viscosity than 3000 seconds Redwood at 70 degs. Fah.

(5) ;Oils should in no case be lower in closed flash point than 350 degs. Fah.

(6) ;If the oil is to be used on an enclosed-crank-case high-speed engine in which the same lubricant is used both for the compressor, and in the crank case, it should have a closed flash point of not less than 400 degs. Fah. (It should be borne in mind that " open " flash point tests give results 20 degs. to 30 degs. Fah. higher than the closed tests on these types of oils).