US1911508A - Strainer - Google Patents

Description

L. P. HOFF May 30, 1933.

S TRAI NER Filed Sept. 25, 1950 Patented May 30, 1933 UNETED STATES PATENToFFIcs LEIGH P. norr, or BALA-CYNWYD', PENNSYLVANIA, AssienoR TO THE ALLEN}- SHERMAN-HOFF COMPANY, A CORPORATION or PENNSYLVANIA STRAINER Application filed September 25, '1930. Serial No. 484,307.

This invention relates to strainers, and more particularly to self cleaning strainers adapted to prevent the entry of foreign material into fluid pumps and the like.

In a large number of industrial operations it is necessary. to pump water or other liquids containing a certain amount of solid abrasive material. Pumps have beendesigned which are especially suited for pumping liquid con 1 taining ash or other abrasive material if the particles of material are not of too great size. It therefore becomes necessary to provide some means of preventing particles of solid material greater than a certain size from entering the pump. A particular instance where my strainer .is very advantageous is in a recirculating ash disposal system for a boilerfurnace. In this system water under high pressure is discharged through jets or nozzles and the ash from the furnace is carried to a sump by the water so discharged. The sump is provided with a number of baflies which accomplish a partial separation of water and ash and the 2 separated water passes into a baflled ofi' portion of the sump from which it isdrawn by a high pressure piunp and again discharged through the nozzles.

Although the water and ash may be fairly well separated in the sump, it is important that a strainer be provided in the intake of the high pressure pump to prevent particles of ash from entering the pump and causing excessive wear both onthe pump and the nozzles. The strainer also eliminates the danger of clogging the nozzles and the small clearance spaces of the pump.

It is among the objects of my invention, therefore, to provide a strainer particularly adapted for use in the above described apparatus.

A further object of my invention is to provide a strainer adapted to be fitted into the intake pipe of a pump which will prevent large particles of solid material from en tering thepump.

Another object is the provision of a self cleaning strainer which is automatic in operation for preventing large particles of'solid material from entering a pump.

Another object ofmy invention is the provision of a strainer which is of simple construction and which may be economically manufactured and is particularly adapted to easy renewal'of the wearing parts.

Other objects of my invention will appear from the following description of one form thereof, reference being had to the accompanying drawing in which:

Fig. lis a sectional side elevation illus- 6'0 trating my strainer in position in the intake pipe or pump;

Fig. 2 is a plan section taken on the line, 2-2 of Fig. 1; Fig. 3 is a detached perspective view the screen carrying cage and screen;

Fig. 4 illustrates theposition of the screen when water is being pumped; 1

Fig. 5 illustrates the position thefscreen assumes when the pump stops, and water it flows back through the strainer. I

The body of my strainer is made up of an outer cylindrical shell 1 having a flange 2 at its top. A removable cover plate 3 is secured in place on the top of the shell 1 by the bolts 4. On one side of the shell 1 is secured a short section of pipe 5 which form'sthe outlet from the strainer. This pipe 5 isconnected to the pump intake pipe 6. A ring 7 is se cured in place on the inner surface of the shell 86- 1 at a point somewhat below'the outlet openbe drawn up to the screen 9 and the water will 7 pass out-throughthe outletopening 8 to the pump while most ofthe solid matter will be held'back bythe screen. When water is flow ing through the screen to the pump, the centerpart of the screen 9 will be bent upwardly, as best seen in Fig. 4, by the action of the r water flowing upwardly through it and the 1% this bending action will free any small partipressure of the solid material on its under side. As the outlet opening 8 is above the screen 9, when the pump is stopped the water in the intake pipe 6 and in the upper portion of the strainer housing 1 will flow back down through the screen 9 and flush the solid material collected on the under side ofthe screen back into the sump. This back flow will also bend thescreen downwardly to ap proximately the position shown in Fi 5 and cles of material which may have become lodged in the mesh of the screen.

The upper end of the screen cage 10 isadapted to abut against the top cover plate 25 and serves to hold the screen 9 down in posi' tion against the upward pressure of material on its under side when the pump is operating. This basket also serves as a convenient handle with which to remove the screen when it is desired to change the size of the screen mesh.

It will be noted that the area of the screen 9 in the housing 1 is large compared to that of the outlet pipe 6. Thus the flow through the screen will be relatively slow and wear will be reduced to a minimum. This construction also greatly reduces the power required to draw the liquid through the strainer.

If desired the screen 9 maybe made rigid instead of flexible as illustrated and the strainer will still be substantially self cleaning due to the back flow of water therethrough.

From the above description it will be seen that my improved strainer is particularly adapted to be used with pumps which are designed for pumping water carrying solid material. As above explained, my strainer is self cleaning and therefore eliminates the necessity of providing a hand hole for manually cleaning the screen of the strainer at more or less frequent intervals.

Although I have shown and described a preferred form of my invention, it will be seen by those skilled in the art that modifications and variations thereof may be made without departing from the spirit of my invention. I do not therefore, limit myself to the precise details shown and described, but claim as my invention, all embodiments thereof, coming within the scope'of the appended claims.

I claim: v

1. A strainer comprising an outer shell having a bottom inlet opening'and an outlet opening on one side, aremovable closure for the top of said shell, a flexible screen disposed within said shell at a point'below said outlet opening and means for maintaining the periphery of said screen. in fixed relation to the walls of said shell, while permitting movement of the central portion ofsaid screen in a direction parallel to the path of material passing through the strainer.

2. A self cleaning strainer comprising a casing having vertically spaced inlet and discharge openings, said inlet opening being be low said discharge opening, a flexible screen extending across said casing between said inlet and discharge openings, and means for maintaining the peripheryl of said screen stationary relative to said housing while permitting the central portion of said screen to move vertically.

3. In a strainer, the combination of a housing having vertically spaced inlet and outlet openings, said outlet opening being disposed above said inlet opening, and a screen adapted to bend upwardly in its central portion when material is passing throughsaid housing from said inlet to said outlet, and to bend downwardly when material is passing throughsaid housing from said outlet to said inlet. I i

1. A self cleaning strainer for mixtures of liquid and solid abrasive material comprising, a casing having vertically spaced inlet and discharge openings, said inlet opening being below said discharge opening, a flexible screen extending across said casing between said inlet and'discharge openings, and means for maintaining the periphery of said screen stationary relative to said housing while per mitting the central portion of said screen to move vertically, said screen being adapted to be flexed upwardly by flow of the mixture from said inlet to said discharge opening and to be flexed downwardly when said flow from LEIGH P. HOFF.

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