US2439763A - Fire-extinguishing pump - Google Patents

Description

R'. zn-:scHANG FIRE-EXTINGUISHING PUMP Filed June 21, 1 944 April 13,1948.

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A ltorney' Hlll l w 2 2 M ,y I l 2 i a 3, J

Patented Apr. 13, 1948 .2433563 riss-cirrmeulsiiiuc ruhr diehard .zieschang Brentford, :england assigner to The, Pyrcne Company Lili! @il Elislend? o British company Application June l21, 1944,'Serial No. .541,416

` InGreat Britain July 1, 1943 4 claims.' (o1. 10a-19.2)

This `invention Vrelates to that kind oi doubleacting pump in which a handfoperated piston reclprocates vertically in a cylinder placed within a container for liquid to be expelled and which may be used as a lire-.extinguishing apparatus.

-In this kkind of vpump the liquid is drawn into the Vcylinder Von the up-stroke through a non.- return Yvalve at the bottom, and on the down,- stro'ke it ls necessary to ensure that an adequate quantity of liquid passes to the upper side of the piston so that above the piston the cylinder is full of liquid when the next up-stroke begins. In existing pumps this is done by making a'large central passage axially through the piston and controlling it by a ball valve mounted in a perfo.,- rated cage immediately above the piston. VIn use it is found that the amount of liquid discharged on the up-stroke differs from the amount discharged on the down-stroke, and that ,on changing over from the .down-stroke to the up.- stroke there is a distinct halt or check in the discharge of liquid. My primary object is to reduce this halt or check to a minimum and to render the discharge more nearly uniform throughout.

According to this invention I use `a clack valve mounted above the piston tocontrol one or more axial passages in the piston, and I find that the halt or check at the end of the downfstroke is materially reduced, apparently 4because pf a cushioning eiect produced by the body of liquid which then -lies between the piston and the clacl valve `and which may be regarded as trapped between lthose two parts. I prefer to make the seal between the piston and the cylinder as v,close as possible and to make the clack -valve wholly close the passages in the piston so that on the upc-stroke the assembly vacts as a solid piston dis placing all the liquid before it, e It is not feasible to .expel all this liquid from the pump, because if this were done the amount vdriven J'out would be much greater than that on the downsstrolce, during which some (and indeed the greater part)V of the liquid that passes through the piston must enter the cylinder, only the relatively small remainder heini-i discharged. Accordingly 4it is necessary to vensure that there .is escape path of predetermined ydimensions for that part off'gth'e liquid which is displaced by the piston on the up-stroke but which is .not discharged. Thislmay conveniently be done by .providing a predeterT mined clearance or tolerance between the piston rod and that part 'in which it is carried at the top of the pump. Y f

`Qll the down.-strclfrc the piston :and clock yalye part company oud liquid flows fthiouehthe Iii 2 c passage crpasssses inthe piston and clock-valve and .into the kcylinder alcove the clock valve, as well as to discharge outletly mailing .the vari-.- ous passages of appropriate dimensions, it is possihle to determine exactly what proportion of thc liquid so displaced is delivered to the .discharge outlet.

l that `by these apparently simple cl-teratiohs I am in ,fact able to produce. a considerable improvement vin operation- The .discharge on both i,rokes .can ,be made more uniform, that is to say, Wbstantially the same volume of `liquid erm-led on each stroke, in addition tothe reduction in the halt or check at .the cud .of .the down.-

The piston is preferably mounted to slide ou o hol-low piston rod placed inside and concehtrif cally with the cylinder and formed with two sets of ports controlled by the piston, the liquid that is boing discharged passing through yche .or other of 'these sets of ports in accordance with the position ofthe ypiston and `:flowing through the holloylr piston rod ou its Way out of the pump- The rod also forms a guilde for the clak valve.

Ih order that the invention 4may he vclearly understood ah'ol readily carried into eiiect, one pump constructed according .to the invention, :tof gether with one modicatiorl, will now be described ,by Way of example -withreference to the accompanying drawings, irl which:

4Figure 1 yis a central vertical section through thezpurpp; and

Figures -:2 and 3 show ithefpiston assembly ou the lup and down stroke respectively.

lihegnump, which is intended for use vas a nreextinguish'el, comprisesfascontainer I with a base flange t and a iixed head 3. A pump cylinder ,d is provided within the container and at its lower end is carried in a fitting 2 5 `which contains a nonfreturn Valve 6 that controls an inlet passage 'l' `forkthe liquid. A hollow piston rod 8 works in the cylinder 4 and is moved by an operating handle d This rod is formed with two sets .of ports, ll1) and yll,-.which are .controlle'dbya piston assembly composed of a piston l2 and a clack valve i3. lThe piston is proyided withan ,expanr sible pistonring I 4 to ,ensure that itlnales a tight seal with the inner Wall ,of the cylinder. The Piston l2 canrslide on the rod kv8 between an end cap l5 `and a shoulder lli V*formed on :the rod, and :the slack `Valve I3 :can slidehetween the piston and sa shoulder AIl formed on the rod.

The piston l2 is formed with two narrow axial passages t8, both at ,auch a radial vdistance from the axis that :theylare completely closed zby ,the

3 lower surface of the clack valve I3 on the upstroke. The clack valve I3 is formed with axial grooves I9 which constitute ports or passages between the valve I3 and the piston rod 8.

At its upper end the cylinder 4 makes a tight iit in a fitting 20, and the piston rod 8 passes through this fitting with a clearance 2I which provides the escape path on the up-stroke.

In operation the piston I2 and clack valve I3 are in contact on the up-stroke as shown in Figure 2 so that the passages I 3 through the piston I2 are closed. In consequence the assembly then acts as a solid piston. Some o the liquid displaced flows downwards through the passages I9 and the ports I into the inside of the piston rod 8, and is positively expelled through the tube 22 as hereinafter described. The remainder is driven upwards and passes back into the interior of the container through the escape path 2I. On the down-stroke the piston I2 and clack valve I3 part company, the ports I0 are closed and the ports I I uncovered, as shown in Figure 3, and the volume of liquid that is to be positively expelled passes into the piston rod 8 through the ports II. The remainder of the liquid displaced passes through the passages I8 in the piston I2 and I9 in the clack-valve I3 to the upper side of the clack valve in a volume sucient to maintain the cylinder full of liquid above the clack valve. At the end 'of the down-stroke, there is of course a momentary delay while the piston I2 is stationary and while the cap I5 on the end of the piston rod 3 is moving upwards to come into contact `with the piston, but it is found that in practice this has no noticeable effect on the discharge of liquid from the pump. While the piston I2 is overtaking the clack valve I3 some at least of the liquid trapped in the space between them shown in Figure 3 is being expelled through the ports I0 and this may be regarded as cushioning the change-over and largely eliminating the halt or check in the discharge of liquid at the end of the down-stroke that characterises existing pumps of the kind in question.

The liquid that enters the hollow piston rod 8 is not directly discharged from it to the pump nozzle. Instead I prefer to provide a xed clischarge tube 22 inside the pist-on rod 8 to make this open at the top, so that the liquid forced into the piston rod 8 flows upwards through it and then downwards through the tube 22. At the bottom the tube 22, which is carried in the iitting E, communicates by a passage 23 with an upward cylinder through an outlet passage in the head and this is controlled by a ball valve which is forced oi its seat by the pressure of the liquid when pumping begins, However, internal pressure is often set up in consequence of an increase in the atmospheric temperature and leakage then takes place past this ball valve. In the preferred pump according to the present invention, the upper end of the tube 22 forms a comparatively small valve seat 2l which, when the pump is not in use, is tightly closed by a valve member 28 placed within the top of the piston rod 8 and urged downwards by a spring 2S which bears on the underside of the handle 3. The handle is held in the closed position by a bayonet joint 30, the female member of this joint being xed to the head 3 of the pump. On being released, the handle can be moved upwards and carries with it the piston rod 8 and the valve 28.

Since liquid is expelled through the escape path 2| on the 11p-stroke, a device 3|, urged into contact with the iitting 20 by a spring 32, is provided for stripping liquid from the piston rod Il.

I iind that the action of the pump is improved and the discharge made more uniform if I provide a closed air pocket in communication with the top of the pump cylinder. By this means the air is under slight compression when the pump is being operated, and so forms an elastic cushion which reduces the uctuations or interruptions in the stream of the expelled liquid as the piston 4changes its direction of movement. This -air pocket is provided by forming a lateral spigot 33 on the fitting 20, suspending from this a tube 34 having its upper end opening into a passage 35 in the spigot and mounting on the tube a closed hollow vessel 36, the tube projecting downwards through the top of the vessel and terminating in an open end close to the bottom of the vessel.

One advantage that is obtained by the use in combination of all the features described is that, in contradistinction to existing pumps of the kind in question, the whole pump mechanism can be tested as a unit before being installed in the container and secured to the xed head.

The invention described and claimed in this application differs in important respects from the invention described and claimed in the applicants Patent No. 2,401,785 which resulted from an application -led on the same day as the present application. In the invention of said patent, the claimed construction of the piston assembly is such that it resists but permits some ow of liquid through the piston and valve member passages dierently during the two directions of movement of the piston assembly. Whereas, in the invention of this application, the claimed construction of the piston assembly is such that it prevents ilow of liquid through the piston and clack-valve passages when the clack-valve is in engagement with the piston and permits a limited iiow of liquid through the piston and clack-valve passages when the clack-valve is out of engagement with the piston. The present invention may also include in the above mentioned combination the provision of a relief opening near the top of the pump cylinder, and a closed hollow vessel connected to the pump cylinder near the top thereof and forming an air pocket, features which are not disclosed in said patent.

I claim:

1. In a re extinguishing hand-operated double-acting pump, a vertically arranged pump cylinder provided at its bottom end with a tting having therein an intake passage communicating with the bottom end of said cylinder and provided with a check-Valve permitting liquid to enter but not escape from said cylinder through said passage; a hollow piston rod having openings therein near the lower end thereof; a piston assembly carried byV said piston rod and reciprocatable in said cylinder land exerting pressure on the liquid therein during movement of said piston assembly in both directions; said assembly including a piston having a liquid passage therethrough and slidingly supported for limited movement on said piston rod and cooperating with the openings therein, said assembly also including a clack-valve cooperating with the upper side of said piston and having a 'liquid passage therethrough which is out of alignment with the passage through the piston, said slack-valve being movable by liquid pressure during upward movement of the piston assembly into engagement with the top of the piston, thereby during said movement preventing flow of any liquid through the piston assembly, and said clackvalve being movable by liquid pressure during downward -movement of the piston assembly out of engagement with the top of the piston, thereby during said last mentioned movement permitting a limited flow of liquid through the piston assembly; the aforesaid fitting being also provided with an outlet passage communicating with the upper end of said hollow piston rod; whereby during upward movement of said piston assembly liquid is drawn into the cylinder through said check-valve and at the same time liquid in said cylinder above said piston assembly is expelled through said outlet passage, and whereby during downward movement of said piston assembly some of the liquid in the bottom of said cylinder is permitted to i'low through said piston assembly into the space in said cylinder above the piston assembly and some of said liquid is expelled through said outlet passage.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date MacGregor Oct. 16, 1928 Ward Feb. 24, 1931 Bassett Aug. 4, 1931 Huthslng Sept. 23, 1941 Zieschangr June 11, 1946 Number

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