US2105264A - Apparatus for the generation of foam for fire extinction - Google Patents

Description

H. V. REED Jan. 11, 1938.

APPARATUS FOR THE GENERATION OF FOAM FOR FIRE EXTINCTION Filed July 26, 1935 2 Sheets-Sheet 1 INVENTOR HEEBERTVERNON REED ATTORNEZY.

Jan. 11, 1938. H. v-. REED 2,105,264

I APPARATUS FOR THE GENERATION OF FOAM F OR FIRE EXTINCTION Filed July 26, 1935 Y 2 Sheets-Sheet 2 luvcmoz HERBERT RNONREED I Patented Jan. ll, 1938 mans-ms FOR. Tim GENERATION or man son Fran ax'rme'rroN Herbert Vernon London, England Application July as. 1935, Serlal No. 33,272 In Great Britain August 1, 1934 13 Claims. (cl. 261-76) runner or a separate turbine, or in a mixing channel into which the water is ejected from a 15 turbine driving a centrifugal pump which throws the foam forming substances fed thereto by gravity into the mixing channel. There is also the known injector method of utilizing a jet-of water flowing into a mixing chamber to induce into the chamber the necessary. foam forming substances.

With such methods either a mechanical drive is necessary for the runner, or, if the water itself is utilized to drive the apparatus, then a g considerable amount of its energy is lost, and the prwent invention seeks to avoid any of the known methods by providing a method wherein not only does the water induce, but positively expels, by direct impact, the foam forming substances into a mixing chamber, so that the water and foam forming substances are introduced into the said chamber separately and at such a velocity that they will be intimately mixed into a foam therein, a. particular feature of this method being that the proportion of air introduced is definitely controlled. The means employed for efiecting this separate and distinct introduction of the elements of the final foam, whilst deriving rotary energy from a jet of water, does so with minimum reduction of the water energy so that mamrnum pressure is available for expelling the foam forming substances into the mixing chamber.

The method of making foam according to the apparatus of the invention, therefore, consists in utilizing liquid pistons to induce foam forming substances into the piston cylinders which are of a predetermined and greater volume than the pistons, and at the same time to sweep out the previously induced contents of the cylinders into one part of a mixing chamber before the pistons themselves deliver into another part of the said chamber.

Thus the water and foam forming substances are kept as distinct as possible prior to delivery into the mixing chamber and due to the predetermined volume of the piston cylinders a governed amount of foam forming substance which will be principally air or may be solely air if the saponin or the like has been previously added to the water-will be introduced under pressure into 5 the mixing chamber so as to combine therein with the water to form the foam.

The liquid pistons may be delivered on to one side of a perforated screen in the mixing chamber and the foam forming substances to the other 0 side of the screen, but whether the screen is used or not, the pistons will always follow the foam forming substances into the mixing chamber, the foam forming substances being expelled into a part of the chamber which may circumferen- 15 tially precede the part in which the pistons are delivered as in the rotary piston forming device to be described or be in line with it where a fixed piston forming device is employed as hereafter described. 20

The accompanying drawings illustrate various forms of apparatus for foam making according to the present invention and in these drawings:

Fig, 1 is a longitudinal cross section through apparatus employing a rotating bladed runner. 25

Fig. 2 is a front elevation of the apparatus partly in section.

Fig. 3 is a section on the line t3 of Fig. 1. Fig. 4 is a developed plan of the runner and co-operating parts. 30

Figs. 5 and 6 are a plan view and a longitudinal section, respectively, illustrating an alternative form of mixing device in tube form.

Fig 'l is a longitudinal section illustrating another alternative form of mixing device in 3 tube form.

Figs. 8 and 9 are a transverse section and a side elevation, partly 'in section, respectively, illustrating another alternative form of mixing device. a

In the embodiment of the invention shown in Figures 1 to 4 a cylindrical casing l is provided which houses a. runner 2 mounted on a shaft 3 journaled in plain or ball bearings mounted in bosses I2, it in end plates 4, 5. l

The runner 2 consists of external and internal shroud rings or bands 6, 1- between which are fitted blades 8 disposed obliquely to the axis of the shaft 3, the spaces between the blades opening to either side of the runner and forming passageways for the passage of liquid-pistons across the runner, as will hereinafter appear. The blades 8 may alternatively be longitudinally disposed when used with an obliquely directed liquid jet, the g internal shroud I being suitably supported from the shaft by plates.

The front end plate 4 of the casing l is fitted with a water inlet 9 which may be flanged or screwed to suit any fire-hose coupling and may be perpendicular or inclined to the surface of the end plate 4. The inlet 9 is preferably of nozzle shape decreasing in area in the direction of flow so that the liquid enters the spaces between the runner blades 8 at a sufficiently high velocity.

In addition, orifices or connections Iii, H are provided in the end plate 4 for the admission of air andsapo'nin or the like.

The back end plate 5 has two delivery orifices l4, l5, one H to pass the liquid pistons and the other l5 to pass the air and saponin or the like, ejected by'the pistons. Saponin or the like material may, of course, have been previously mixed with water. A long tube l6 forming a mixing chamber is attached to the end plate 5 and is divided by a perforated metal or wire mesh screen I'l into two compartments and terminates in a nozzle [8. The screen I! may be fitted or associated with bailles I!) (see Figures 5 and 6) to ensure the passage of the liquid over the complete surface thereof so that the air delivered to the lower side of the screen is continually in contact with the liquid stream delivered to the upper side of the screen. The tube l6 may have any.

desired shape and in Figs. 1 and 3 is illustrated as being of substantially equal cross sectional area throughout its length, but is divided by the screen I! so that the cross section of the air compartment gradually diminishes towards the outlet l8 while the cross section of the liquid stream compartment increases in the direction of flow so that the liquid is gradually aerated into foam. The same effect is obtained in Fig. 7 by making the perforated screen l'la conical and placing it concentrically within the mixing tube lGa, or in Fig. 6 by disposing the fiat perforated screen [1b substantially parallel with the upper 'side of the tube l6b which increases in width in the direction of flow. A further method is to deliver the liquid tangentially to the annular space formed between two concentric cylinders 20, 2|, (Figures 8-and 9) the inner one 20 of which is perforated and open to a conduit 22 to be connected to the outlet l5 of the casing through which the foam forming substances, i. e. the air and the saponin, are ejected by the liquid pistons. A conduit 24 communicates with the annular space between the cylinders, and is to be connected to the outlet M of the casing I so that the liquid pistons will be diverted spirally along the annular-space between the cylinders 20, 2| by means of bailles 23, the resulting foam being collected and delivered to the nozzle l8.

The nozzle l8 and the tube I6 may be separated from the end plate 5 and connected thereto by two flexible hoses along which the separate ingredients are conveyed.

As will be seen from Figure 4, the developed shape of the runner blades is straight so that although the jet impinging thereon will cause the runner to rotate, the energy absorbed from the jet will be very small, which is unlike the usual water turbine or centrifugal pump wherein the blades are curved to absorb a considerable or the whole amount of the jet energy. The main purpose of the blades is to cut into the liquid jet and separate it into liquid pistons which are of considerably less volume than that of the spaces between the blades, and which pass with substantially the velocity of the jet along the blade spaces thereby exhausting the spaces to allow of the free admission of air and saponin or the like thereinto through the inlets In, H whilst expelling by direct impact the air and saponin, previously admitted, through the outlets ll, IS, the air and saponin first being expelled through outlet l5 and the pistons themselves following through the outlet l4. Thus, in the runner there is substantially no turbulence and no intimate mixing of the water and foam forming substances, but instead they are kept as separate as possible within the blade spaces and only brought together in the mixing chamber, the high velocity of the various elements resulting in an intimate mixture thereof and a close foam.

It will be noted from Figure 4 that each blade space comes'into register with the outlet IE only after it has passed the inlets Ill, H, and further that it is in register with the outlet when a liquid piston commences its travel across the particular space, i. e., when the latter registers with the nozzle 9. Thus the obliquity of the blades is such l that a blade space, although opening on either side of the runner, never provides a direct passage between the inlets l0, II and the outlet l5. During the passage across the runner of any liquid piston, the blade space along which it is travelling will move circumferentially so that the liquid piston passes out through the outlet ll sub stantially in the original line of the jet.

Thus, as successive blade spaces pass the outlet l5 quantities of air will be expelled therefrom into the mixing chamber and below the screen to produce the necessary volume for foam production within the mixing chamber. between a liquid piston and the volume of foam forming substance swept out there y is definite but subject to variation by varying the ratio of the distance between blades to blade length and also by varying the inclination of the blades to the runner axis.

In the above described arrangement, the liquid pistons may travel through the blade spaces during the time a space takes to travel from the commencement of outlet IE to outlet 14; the induction action of the pistons would then be indirect, the free admission of air being dueto the exhaustion of the spaces. On the other hand if the runner makes one complete revolution whilst a liquid piston is travelling through a space, then as the space with the piston in it, passes the inlets "I, II a direct induction of the foam forming substances will occur.

I claim:

1. Apparatus of the character described for making foam for fire extinguishing, comprising a casing with a runner mounted to rotate freely therein, blades on the periphery of the runner, the spaces between the blades opening on either side of the runner, a nozzle on one side of the runner for delivering a jet of liquid to the runner blades, the blades and the nozzle being disposed so that rotation of the runner is caused without substantially reducing the energy of the jet and the blades cut into the jet to form liquid pistons which sweep out the spaces between the blades, inlets on the nozzle side of the runner for admitting foam forming substances to the blade The ratio register with said outlet only when the space has passed the inlets and while a liquid piston is travelling along the particular space.

2. Apparatus for making foam for fire extinguishing comprising a casing with a runner mounted to rotate freely therein, blades disposed on the periphery of the runner obliquely across the runner axis and forming straight lines when the runner is developed, the spaces between the blades opening on either side of the runner, a nozzle on one side of the runner for delivering a {ct of liquid to the runner blades which cut the jet into liquid pistons, an inlet on the nozzle side of the runner for admitting foam forming substances to the blade spaces and separate delivery outlets for the liquid pistons and the foam forming substances to a mixing chamber on the opposite side: of the runner, the obliquity of the blades being such that no direct passage is provided between the inlet and outlet of the foam forming substances.

3. Apparatus of the character described, for making foam for fire extinguishing, comprising a tubular mixing chamber, a perforated screen dividing the chamber longitudinally into two compartments, and means for creating liquid pistons and causing the same to deliver foam forming substances to one compartment of the mixing chamber before they themselves deliver into the'other compartment of the said chamber.

4. Apparatus of the character described, for making foam for fire extinguishing, comprising a tubular mixing chamber of substantially constant cross section area through its length, a perforated screen dividing the chamber longitudi-- nally into two compartments so that one of thecompartments gradually diminishes in area towards the outlet end of the mixing chamber, and means for creating liquid pistons and causing same to deliver foam forming substances to the compartment of gradually diminishing area before they themselves deliver into the other compartment of the mixing chamber,

5. Apparatus of the character described, for

making foam for fire extinguishing, comprising a making foam for fire extinguishing, comprising a casing having an inlet for liquid and an outlet for liquid and foam forming substances, rotary means within said casing for dividing a stream of liquid flowing therethrough into successive liquid pistons, means for the supply of foam forming substances in front of each liquid piston prior to its discharge from said casing through said outlet, and a mixing chamber disposed to receive liquid and foam forming substances discharged from said casing through said outlet.

. 7.-Apparatus as set forth in claim 6, wherein a perforated screen divides the mixing chamber into two compartments one disposed in advance of the other as regards the direction of rotation of the liquid pistons within the casing so that the foam forming substances are discharged into one of said chambers in advance of the discharge of the liquid pistons into the other of said chambers.

8. In combination with apparatus according to claim 6, a perforated screen dividing the mixing chamber into two compartments, one disposed in advance of the other as regards the direction of rotation of the liquid pistons within the casing so that the foam forming substances are discharged into one of said chambers inadvance of the discharge of the liquid pistons into the other of said chambers, and baiiles in said last mentioned chamber to deflect the liquid from side to side during its passage through said chamber.

9. Apparatus of the character described, for making foam for fire extinguishing, comprising a mixing chamber, rotary means for creating successive liquid pistons and causing each to deliver in front of it a quantity of air and chemical foam formant to the said chamber before itself discharging into the chamber, said means including a nozzle delivering a jet of liquid which is cut into the liquid pistons, an air inlet angularly preceding the nozzle and an inlet for chemical foam formant angularly preceding the air inlet.

10. Apparatusof the character described for making foam for fire extinguishing, comprising a casing housing a liquid piston forming device and a nozzle for delivering a jet of liquid to said device, said device and nozzle being mounted for relative rotation, a series of blades immovably mounted in said device and so disposed in relation to the nozzle that they cause relative r'ota-. tion between themselves and the nozzle without substantially reducing the energy of the jet, whilst cutting the jet into successive liquid pistons each of which passes axially along and sweeps out the contents of a blade space before it, inlets for foam forming substances, arranged on the nozzle side of said device so that the liquid pistons moving axially along the blade spaces induce foam forming substances behind them,

' and a mixing chamber into which the contents of the blade spaces swept out by the pistons and the pistons deliver in succession.

11. Apparatus of the characterdescribed for making foam for fire extinguishing, comprising a casing housing a liquid piston forming device tion to the nozzle that they cause relative rotation between themselves and the nozzle without substantially reducing the energy of the jet,

whilst cutting the jet into successive liquid pistons each of which passes axially along and sweeps out the contents of a blade space before it, inlets for foam forming substances, arranged on the nozzle side of said device so that the liquid pistons moving axially along the-blade spaces induce foam forming substances behind them, separate delivery outlets for the liquid pistons and the foam forming substances swept out by the pistons to a mixing chamber on the opposite side of said device, the outlet for the liquid pistons being arranged in advance of the outlet for the foam forming substances.

12. Apparatus of the character described for making foam for fire extinguishing, comprising a. casing, a rurmer rotatably mounted in and about the axis of the casing, blades on the periphery of the runner extending across the casing between the sides thereof in which the axis of the runner is mounted, and forming spacesopen at each end, a mixing chamber having an entrance which the spaces pass in succession as the runner rotates, a nozzle for delivering a Jet of liquid to the opposite ends of the blade spaces, the blades and the nomle being disposed so that rotation of the runher is caused without substantiallyreducing the energy of the jet, and the blades 'cut into thejet to form liquid pistons which sweep out the contents of the blade spaces and then follow themselves into the 'mixing chamber, and inlets for admitting foam forming substances to be induced by the liquid pistons, said inlet anglllarly preceding the nozzle so that the foam forming substances are induced into the blade spaces before the said spaces open to the entrance to the mixing chamber.

13.Apparatus oi' the character described for making foam for flre extinguishing, comprising a casing having parallel side plates, a runner rotatably mounted between the side plates, a mixing chamber having an entrance in one side plate, blades on the periphery of the runner ex- 20 tending from side plate to side plate and forming spaces open at each end and successively aromas passingthe entrance to the mixing chamber as the runner rotates. a nozzle attached to an inlet in the other side plate for delivering a jet of liqaid to the blade spaces as they pass the inlet,

the blades and the nozzle being disposed so that rotation of the nmner is caused without substantially reducing the energy of the jet, and the blades cut into the Jet to form liquid pistons which sweep out the contents of the blade spaces HERBERT VERNON REED.

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