gas analysis, temperature of escaping gases and results of tests and plant records. With careful attention paid to the draft readings and adjustments of dampers, this method will usually result in considerable saving. The recognition that trained engineers are rapidly receiving is most convincing testimony that the value of scientific management is becoming increasingly appreciated.

gage.

Co-operation with the employer and with other employees is absolutely necessary for successful operation of the plant. If the plant requires new equipment or repairs to old equipment in order to improve its economy, these improvements should be suggested to the employer, with an explanation of the resulting advantages.

CHAPTER XXIV

FUEL OIL BURNING APPLIANCES

In its course from the point of delivery at the plant to the burners the oil must pass through a number of appliances, which are necessary for the complete equipment of any oil burning plant. In this discussion we shall follow the oil in its journey through the plant and describe briefly the various appliances required for handling it.

FIG. 123. The cars are shown on the unloading track of the Redondo Steam Plant of the Southern California Edison Company and the oil is emptied from them into the flume which runs beside the tank; thence it goes into a small underground tank from which it is pumped into the main storage tank.

Oil may be delivered at the plant either by rail in tank cars, or by water in barges or tank steamers specially constructed for the purpose. From these it is pumped into large storage tanks, which may be of either concrete or steel.

Storage Tanks. For storage tanks are used.

power plants large cylindrical steel
These are usually set on the ground

outside the plant, and are built in any desired size up to 50,000 bbl. capacity. They are built up of riveted steel plates, the thickness of plate and strength of riveted joint being proportioned in accordance with the usual safety rules based on the internal pressure due to the head of oil inside the tank. Thus if the tank is 30 ft. high the internal pressure will be that due to 30 ft. head of oil, or approximately 15 lb. per square inch. It is customary to surround the storage tank by a concrete wall about 10 ft. high far enough away from the tank so that the entire

FIG. 124.-Main oil storage tanks at Station C, Pacific Gas and Electric Company, Oakland, California. Tank in foreground is set low for fire protection purposes, while tank in rear is surrounded by concrete retaining walls. contents of the tank will be held in by the wall in case of a leak in the tank. This is to prevent the oil from leaking out to the surrounding country..

The size of storage tank required depends on two factors: 1. Quantity of oil to be burned.

This second factor depends on the location of plant, the method of delivery, and the probability of interruptions in delivery, all of which matters must be carefully considered in determining the number of days oil supply that should be carried at the plant. Most power plants are provided with tanks of sufficient size to enable them to keep from 10 to 30 days' supply of oil on hand.

This storage capacity should preferably be divided among two or more tanks rather than all concentrated in a single tank, as this will enable one tank to be emptied for cleaning and repairs without shutting down the entire plant.

In built up districts within the fire limits of cities it is not permissible to locate the storage tanks above ground. The National Board of Fire Underwriters have adopted certain rules for the location of oil storage tanks, which will be found in

FIG. 125.-One of the pumps which handle the oil from the main storage tank to the auxiliary tank. This pump was originally arranged for belt drive but was found unsatisfactory. The gearing is now direct.

Appendix III, page 415. Similar rules have been adopted by several cities. In general these rules provide that within the fire limits of cities the tank must be located so that its top is at least 3 ft. below the level of the fireroom floor and below the lowest pipe in the building to be supplied. The tank must be set on a firm foundation and covered with soft earth or sand, no air space being allowed immediately outside the tank.

Every oil storage tank must be provided with the following attachments:

Filling pipe

Suction pipe

Vent pipe

Smothering pipe

Overflow pipe

Measuring rod or chain

For tanks less than 1000 gal. capacity the filling pipe and vent pipe may be on the same connection. For larger tanks separate connections are required. The vent pipe must extend from the top of the tank to a point outside the building at least 12 ft. above the top of the highest tank car from which the storage tank may be filled. All outlets on the tank should be located on top, the suction pipe running down inside the tank to near the bottom. The smothering pipe consists of a small steam pipe through which steam can be blown in case of fire, thus keeping air away and effectually smothering the flames. The overflow pipe is arranged to carry back to the storage tank all oil not used. An automatic relief valve is provided on the oil pump discharge set to open at a predetermined pressure, and discharging through the overflow pipe back to the storage tank. All pipes should be run as direct as possible and pitched toward the storage tank. The oil in the tank may be measured by means of a rod or chain let down through the top of the tank. The use of gage glasses should be avoided as they are liable to break, causing leakage of oil.

Many power plants are provided with a service tank located under the fireroom floor, in addition to the main storage tank outside the building. The service tank is filled at intervals from the storage tank, and the oil pumps take their supply from the service tank and distribute it to the oil burners.

Measurement of Oil.-Oil is ordinarily measured by passing a rod or chain down through the top of the storage tank, the rod being marked off in feet, inches and fractions of an inch. By sounding to the bottom of the tank, the depth of oil can be determined very accurately. A more convenient method, though not quite so accurate, is to use a float with a chain passing over a pulley at the top of the tank, the outer end having a