STRAINERS AND HEATERS.
All fuel oils carry a certain amount of foreign mat ter in suspension. Some of the impurities settle out while the oil is in the storage tank ; but if the oil is heavy and viscous, much of the foreign matter will remain in suspension and be pumped to the burners unless a strainer is provided. Since most burners break up or atomize the oil by forcing it through small orifices, it is essential that there be an efficient strainer in the oil feed line, to remove all traces of gritty matter before the oil reaches the burner.
A good oil strainer must separate all solid matter suspended in the oil, and be large enough to retain the material removed for a•considerable time, unless it is of a self-cleaning type.
Strainers are made in various sizes and shapes, a wire netting or perforated metal of some sort being used to separate the dirt from the oil. A few are illustrated below, to indicate the various ingenious devices that have been contrived.
Fig. 38 illustrates a simple basket type of oil strainer. This type is cleaned by removing the plug at the top, taking out the basket, and rinsing it with kerosene. Fig. 39 illustrates the method of connect ing a set of basket strainers. It is necessary to con nect them in duplicate as shown, to permit continu ous operation of pumps and burners while one strainer is being cleaned.
Fig. 40 shows a set of duplex oil strainers and plug cocks. Either strainer can be used while the other is being cleaned, without affecting the oil pressure. Fig. 41 illustrates a compact self cleaning oil strainer. The oil passes to the center, down the central tube and is strained by passing through the perforated cone. The clean oil passes up to the exit, while the dirt set tles at the bottom of the strainer. By opening the by pass valve, oil flows directly through the line. Then by opening the valve at the bottom of the strainer the dirt can be forced out with steam, which is sup plied by opening the small valve at the side of the strainer.
This type of strainer has many advantages. It can be operated and cleaned without soiling the hands, and is thus a time-saver. The flow or pressure of the oil is not changed while cleaning. And if a leak in the suction line causes difficulty in the operation of the pump, it can be readily located by closing the suc tion valve at the pump and opening the steam valve on the strainer. In this manner steam is forced into
the suction line and the leak will be indicated by the issuing steam. Heavy oil can also be heated in this manner when there is difficulty in starting the oil pump on a cold morning.
The object in atomizing the oil is to break it up into minute particles, and thus expose the maximum surface to contact with the air. This is accomplished in the burner, but to make the operation efficient, the oil must first be heated. A further advantage of heating the oil lies in the fact that oil will burn more quickly at a high temperature, because the hydro carbons are more readily separated. With the ato mizing type of oil burner, the oil is heated to a tem perature of about 125 degrees F. In the mechanical type, the temperature varies from 150 degrees to 220 degrees F.
A few of the many types of oil heaters in use. are illustrated herewith. The upper part of Fig. 43 shows a copper coil through which steam is circu lated ; the coil is submerged in a vessel through which the oil is pumped. The large heating surface of such a coil makes it an efficient type of heater. The lower part of Fig. 43 shows the condensing type of oil heater. The oil passes through the oil inlet into a in. pipe, which is 'enclosed by a 4 in. pipe. Upon reaching the end of the inner pipe it passes into and returns through the annular space between the inner and outer pipes to the discharge chamber. Steam fills the body of the heater and an outlet for the condensed water is placed at the bottom.
Fig. 44 illustrates a corrugated type of oil heater, in which the oil passes through the corrugated inner chamber and is heated by the steam that passes into the body of the heater. Fig. 45 illustrates a multiunit oil heater, constructed of extra heavy wrought iron pipe. The oil passes hrough the inner pipe and is heated by the steam in the annular space between the two pipes. It will be noticed that all joints are made up on the outside. The return bends are extra heavy brass castings for the oil pipes and standard high pressure ammonia fittings for the steam connections. This type of heater can be made of as many units as may be required, and can be connected in duplicate so that either heater can be cut in or out, as desired.