US2701452A - Tube ice-making apparatus - Google Patents

Description

Feb. 8, 1955 N. E. HOPKINS 2,701,452

TUBE ICE-MAKING APPARATUS Filed July 28, 195o s sheets-sheet `1,

Y @if a ATTORNEY Feb. 8, 1955 N. E. HOPKINS TUBE ICE- MAKING APPARATUS Filed July 28, -1950 5 Sheets-Sheet 2 INVENTOR ATTORN Feb. 8, 1955 N. E. HOPKINS TUBE 1cEMAK1NG APPARATUS 5 Sheets-Sheet 3 Filed July 28, 1950 m P m JW m MA Q@ @IL AS ww IT l l I I I I l l l l l l I I I I l TUBE ICE-MAKHNG APPARATUS Neil E. Hopkins, York, Pa., assignor to Flalrice Corporation, Brooklyn, N. Y., a corporation of Delaware Application . lluly 28, 1950, Serial No. 176,270

Claims. (Cl. 62--105) This invention relates vto refrigeration, and more in particular to making ice in the form of cubes or the like by the use of machines such as those disclosed in the copending applications of Meldon Gerald Leeson: Serial No. 573,939, filed January 22, 1945, now Patent 2,524,815, and Serial No. 686,021, filed July 24, 1946, now Patent 2,549,747, and also in the copending applications of William M. Grandia, Serial No. 57,158, led October 29, 1948, now Patent 2,593,874, and of Rodney F. Lauer and Claude V. Shurtluff, Serial No. 174,216, tiled July 17, 1950, and issued as Patent No. 2,633,005.

The above-identified applications disclose 'machines and methods for making ice in the form of cubes which may have cylindrical holes therethrough. The illustrative embodiment of the present invention is in the form of an embodiment of or an improvement on the copending application of Rodney F. Lauer and Claude V. Shurtluif, which invention is disclosed specifically in apparatus which comprises an ice-making machine or apparatus which, except as specifically pointed out, is identical with that disclosed in application Serial No. 57,158, which, in turn, incorporates specific structure shown in application Serial No. 686,021. The structure herein disclosed is therefore described only sufficiently for the understanding of the present invention, and reference may be had to the above-identified copending applications for more f detailed discussions of certain features of construction and operation of this general type of apparatus.

It is an object of the present invention to provide improved apparatus of the above character and to provide an improved mode of operation thereof. It is a further object to provide improved modes of operation and control for apparatus of the above character. It is a further object to provide for the above withapparatus which is practical in every respect from a commercial standpoint. These and other objects will be inpart obvious and will in part be pointed out below. y

The invention accordingly-consists in the features of construction, combinations of elements, .and arrangements of parts as will be exemplified in thestructurev to be hereinafter described` and the scope ofthe application of which will be indicated in the -following claims.

In the illustrative embodimentofthe invention disclosed in application Serial' No. 57,158, ice cubes are formed by tirst freezing-the water to form ice rods or columns which are square in cross-section and may have a cylindrical hole therethrough, and these columns are melted free and then are cut or broken into lengths to form the cubes. The columns of ice are formed by flowing water through vertical freezing tubes which form passageways along the side walls of which the water flows while these walls are refrigerated sufficiently to cause ice to build up. The rate of ow and the other conditions are so controlled that clear, hard ice builds up in an even layer and the freezing operation is continued until the column is substantially solid or, if desirable, has a hole of predetermined size therethrough.

A harvesting operation is then started which involves melting the cubes free so that they fall from the tubes, and as they emerge from the bottoms of the tubes they are severed into predetermined lengths to form the cubes. During the freezing operation water is circulated through the tubes at a rate which is in excess of the amount frozen, and the water in excess of that which is frozen is collected in a sump tank to which fresh water is added and from which water is pumped and recirculated through the freezing tubes.

ZS Patented Feb. 8, 1955 With apparatus such as that referred to above, difficulty has been encountered in producing uniform high quality ice without the attention of an operator. Machines such as those referred to above have, however, been sold as package units; that is, self-contained units are built and sold for installation by the purchaser, and are put into operation by making connections to the water supply and drain and to a source of electric power. The operation is then automatic with the ice-making and harvesting operations being carried on in accordance with a controlled cycle. Under some circumstances the salt concentration is high so that there is a tendency for the ice to become cloudy and commercially unacceptable, and special care must be taken to maintain the salt concentrations within permissible limits. It is advisable, however, to avoid complicated and costly equipment and to use a minimum amount of water consistent with the production of maximum quantities of commercially acceptable ice.

An important feature of this type of equipment from a commercial standpoint is that the ice produced is uniform in size and shape and, of course, is of high quality; that is, the ice cubes are clear and hard and of substantially the same size and shape. It has been found, however, that apparatus such as that referred to above will, under some conditions of operation, produce ice which is not uniform and, in fact, which is not entirely satisfactory frorn a commercial standpoint. For example, if the ice builds up at an excessive rate in one particular tube it may freeze solid and become sub-cooled excessively prior to the end of the freezing cycle and then part or all of it may not become dislodged during the harvesting cycle. If due to this or another cause, a body of ice remains in one of the freezing tubes after a harvestu ing cycle has been completed, there is great danger that the tube will be damaged during the next freezing operation.

Provision has been made in apparatus of the above character for preventing the completion of a freezing operation if one or more of the tubes are obstructed. However, it is still important to insure that ice builds up at the desired rate in all of the freezing tubes. As indicated above, with this type of apparatus, when water is flowed down the inner walls of the freezing tubes at a very rapid rate, clear and hard ice forms in an even layer. This is because the rapidly owing layer of water covers the entire inner surfaces of each of the tubes, and this effect has been obtained in the past by projecting individual streams of the water against the top of each of the four side wall surfaces of each tube. Thus four streams are projected into each tube from corresponding outlets or openings in a nipple or water distributor in the bottom of a water header where the water is maintained under pressure by the water circulating pump referred to above.

As discussed in the copending application of Rodney F. Lauer and Claude V. Shurtluff, it was found that one or more of the outlets from these nipples was apt to become clogged; for example, by the accumulation of crystallized salts when the salt concentration is high. When one or more of the water outlets in a nozzle became clogged there was a corresponding decrease in the rate at which water flowed through that tube. Thus, While the water tended to spread out over the entire inner surface of that tube, the rate of water flow was reduced because of the lesser quantity which was being delivered to the tube. This reduced rate of water flow not only caused the ice in that tube to become milky or even white and spongy, but this reduced rate of flow caused the ice to build up at an increased rate so that that particular tube became lledwith a column of ice prior to the completion of the freezing operation in the other tubes. For example, at times the ice completely lled one tube while relatively thin shells were formed in the other tubes.

In the apparatus of Serial No. 57,158 the harvesting operation is initiated whenever one or more of the tubes becomes lled with ice suiciently to interfere materially with the ow of water therethrough. This has been eX- tremely satisfactory as a mode of control for most conditions of operation because the freezing is uniform in the various tubes and they all become substantially filled with columns of ice of high quaiity at substantially the aromas same time; that is, by the time one or more of the tubes has the water tiow obstructed by the ice sufliciently to initiate the harvesting operation. However, with such control it has been found that, when there is an obstruction as discussed above in one or more openings 1n a nipple supplying water to a tube, so that ice builds up and fills that tube with ice prematurely in the cycle, then a harvesting cycle is also started prematurely. As indicated above, under some circumstances the one tube having obstructions in its water supply openings is lilled with poor quality ice while the other tubes have only shells of ice in them and, therefore, the apparatus produces no ice of acceptable quality and size.

In accordance with the invention of the above-identitied application of Rodney F. Lauer and Claude V. Shurtluff, arrangement is provided for insuring that the water will be distributed evenly and will ow continuously down all of the tube surfaces throughout the entire freezing cycle. That invention contemplates a water distribution arrangement wherein solid particles such as crystallized salts or foreign matter will not interfere with this flow. Thus, the freezing cycle will be carried on to completion without danger of being stopped by the permature building up of ice in the tube. Furthermore,

the water is delivered to the tubes in such a manner that it does not tend to flow at a reduced rate through any area of the freezing surfaces of the tubes.

As indicated above the present invention is in a sense an improvement upon that disclosed in the above-identifiel application of Rodney F. Lauer and Claude V. Shuttlu The present invention provides an improved construction for carrying out the above. Water tlows into the tops of the freezing tubes through unobstructed pipes and it hits a target which is dish-shape so that the water is deflected radially outwardly and upwardly. The target is supported in such a way that it is rigid and yet it may be removed readily for servicing. One illustrative ernbodiment of the invention is particularly adapted for installation on ice-making machines such as the one disclosed in the above-identified coptnding application of William M. Grandia while the other illustrative embodi- Iment is related more closely to the apparatus disclosed in the above-identified application of Rodney F. Lauer and Claude V. Shurtluff.

ln the drawings:

Figure l is a schematic diagram of an ice-making machine of the character referred to above and incorporating the present invention;

Figure 2 is an enlarged top plan view with parts broken away of the water distributor header of Figure l;

Figure 3 is a side elevation with parts broken away of the header of Figure 2;

igure 4 is an end elevation of the header of Figures 2 an 3;

Figure 4A is an enlarged plan View of the water distributor outlets with the center broken away and showing the enlarged size of the outlets to the end tubes;

Figure 5 is an enlarged sectional View of the water distributing nozzle of Figure 3;

Figures 6 and 7 are similar to Figures 2 and 3 respectively, but show another embodiment of the invention.

Figures 8, 9 and l0 are sectional views respectively on the lines 8 8, 9-9 and 10--10 of Figure 7; and,

Figure ll is a section on the line 11-11 of Figure i0.

Referring to Figure l of the drawing there is represented schematically at the top a bank of sixteen freezing tubes 1 to the tops of which water is directed by a header 3 supplied by a pump 5 from a sump tank 7. The water flows down the tubes and some is frozen, and the amount in excess of that frozen in the tubes returns to the sump tank. A oat valve 8 connected to a source of water opens and closes automatically to maintain a predetermined level in the tank. The freezing tubes are cooled by an evaporator 9 to which liquid refrigerant is supplied through a thermostatic valve 11 having a bulb 13. The gas refrigerant from the evaporator is `withdrawn by a compressor having an electric motor 14 hermetically scaled within its casing. The compressed gas passes from the compressor 15 to a watercooled condenser 17 cooled by water supplied through a vulve 18. The refrigerant is here liquefied and passes to evaporator. During the harvesting cycle hot gas retrigerant is passed from the compressor to the evaporator if.; heat the freezing tubes; accordingly, a pipel i9 (indicated by broken lines) is provided having a normallyclosed solenoid valve 21 therein which valve is opened to connect the outlet side of the compressor to the bottom of the evaporator.

Power to operate the machine is supplied through a main control switch 23 to a pair of lines 25 and 27 which are connected directly to the compressor motor. Line 25 is also connected to the armature 29 of a doublethrow solenoid switch 31 and also to one side of a thermostatic switch 33. Line 27 is connected to one side of each of: the solenoid valve 21; the ice cutter motor 37 which operates the mechanism to cut the ice into cubes; the water pump motor 39 which drives pump 5; and the solenoid 41 of switch 31. Switch 31 has its normallyclosed contact 43 connected to the other side of the solenoid ot' valve 21 and also to the other side of motor 37; and it has its normally-opened contact 45 connected to the pump motor 39 and also to one side of a thermostatic switch 47. The other side of switch 47 is connected to solenoid 41 and to switch 33. The operation of the machine will be explained after the construction of the water distributor and the associated parts have been explained in detail.

Referring to the upper portion of Figure l, there is shown the bank of square freezing tubes 1 positioned in side-by-side relationship witha plate 48 between the side walls of cach two adjacent tubes. On the opposite sides of the bank of tubes there are two evaporator sections of evaporator 9 formed by horizontal runs of metal tubing with the sections being connected by headers. The bank of freezing tubes and the evaporator sections are covered by insulation and enclosed in a sheet metal casing. At the top of the bank of tubes there is a horizontal water supply header 53 which is enclosed in an insulation shell, and projecting from the bottom wall of this header into the top of each of tubes 1 is a water distributor nozzle 54 (see Figure 3) which directs water against the inner surfaces of the four walls of its tube.

At the bottom of the freezing tubes there is an icecutting assembly which is not shown but is shown and described in detail in the above-identified applications. This assembly severs the columns of ice which are formed in the tubes into lengths to form the ice cubes which are passed by gravity to a storage bin. At the beginning of the harvesting operation the columns of ice are released by passing hot gas into evaporator 9 and at the same time the ice cutter assembly is started. This operation continues until the temperature of the evaporator rises, thus indicating that the ice has been freed and has dropped from the freezing tubes. At this time the harvesting operation is discontinued and a new freezing operation is started. As indicated above, during the freezing operation water is pumped into header 3 at the top of the freezing tubes and it ows down the entire inner surfaces of each of these tubes. The construction of header 3 is shown in Figures 2 to 5 and will now be described.

Referring to Figures 2, 3 and 4 of the drawings header 3 is formed by the elongated sheet metal supply header 53 and a parallel water discharge pipe or header 49 which has its right-hand end (Figure 3) bent downwardly. The water supply header is enclosed in an insulation shell and the entire header is supported by three brackets 51 which are welded to the supply header 53 and have their ends clamped to the top of the bank of freezing tubes. The water discharge header is supported by sixteen somewhat arcuate water overflow discharge tubes 52 (Figure 5) each of which has one end connected into the top of header 49. The other end of each of tubes S2 projects into the water supply header 53 and thence downwardly through the bottom wall of this header. Thus. each tube 52 connects the upper end of one of the freezing tubes to the top of header 49, and it projects through and is soldered to the water supply header 53 and the top wall of header 49.

As indicated above, header 53 has water distributor nozzles 54 mounted in its bottom wall; illustratively, there being sixteen freezing tubes and nozzles with each tube and its nozzle being in axial alignment. As best shown in Flgure 5, each of the nozzles comprises a sleeve or ferrule 5S and a target or delector 56. Ferrule 55 is soldered to the bottom wall of header 53 and has a central water outlet opening 57 through which water is discharged from the header. Target 56 s somewhat dishshaped and it is supported by two integral arms 59 which (see Figure 3) extend outwardly and upwardly and have their ends bent inwardly so that they engage an annular groove 58 at the lower end of ferrule 55.

During operation the water from header 53 ows through each of the nozzles in a rapidly moving stream and the stream is projected against the upper surface of target 56. Target 56 spreads the water and causes it to flow radially in a smooth thin stream or sheet outwardly against the tube walls. The upturned rim of the target causes the sheet of water to be diverted upwardly so that the water engages the tube walls at substantially the top of the tube. Thus, as described above, the water flows downwardly along the tube walls and it tends to spread evenly and to flow at a rapid rate. It should b e noted that the nozzles provide unobstructed water discharge outlets from the header into the tubes. Thus, particles of even a relatively large size will pass through the nozzles and are washed down the tubes into the sump tank without in any way obstructing the ow of water.

The water discharge header 49 is connected (Figure 1) to the downwardly extending pipe 91 and water isvsupplied from pump 5 to header 53 through a pipe 90. The left-'hand end of header 49 is vented at the left through an inverted U tube 92. Pipe 91 projects downwardly into the enlarged upper end of a pipe 95 which extends to the sump tank 7. Thermostatic bulb 97 of switch 47 is positioned in pipe 95 so that water flows over it from pipe 91 and the bulb is connected through a tube 98 to its switch.

Thel freezing operation has been described above and for more detailed discussions of it reference may be had to the above-identified copending application. For purposes of understanding the present invention, it is sufficient to point out that with the system operating as represented in Figure 1 water flows through the nozzles 54 and thence downwardly through the freezing tubes while the freezing tubes are cooled by the refrigeration system discussed above. Ice of high quality builds up on the tube walls in the forms of columns or tubes which are square in cross section with a central opening therethrough. As the freezing continues, these openings become smaller until the ow of water through the freezing zone is interfered with, at which time the water tends to back up into the tops of the tubes. The water which backs up in any tube tends to flow upwardly through the connecting overflow tube 52 and over into the header 49 (see Figure 5). Water in header 49 ows to the right (Figure l) and thence downwardly through pipe 91 and over bulb 97. This water is cooled and it reduces the -temperature of bulb 97 sufticientlvto open switch 47 and this-initiates the harvesting operation.

It should be noted that switch 33 has its bulb 99 positioned near the top of the bank of freezing tubes and thisvswitch closes and the bulb temperature rises substantially above 30 F. and the switch opens again when the temperature drops. Thus, during the freezing operation this switch is open and, therefore, the opening of switch 47 deenergizes solenoid 41 so as to drop armature 29 away from contact 45, thus stopping the pump motor 39. Armature 29 drops into engagement with contact 43 and this energizes the solenoid of valve 21 so as to open this valve and supply hot gas to the evaporator and it also starts the cutter motor 37.v The columns of ice are therefore thawed from the freezing tubes and they drop down and are severed into cubes by the mechanism operated by motor 37.

When the tubes are free of ice their temperature rises rapidly so that bulb 99 is heated and its switch 33 closes. This energizes solenoid 41 so as to raise armature 29 with the result that the cutter motor 37 is stopped and the solenoid of valve 21 is deenergized so that this valve recloses and hot gas is no longer suppliedto the evaporator. The raising of armature 29 restarts the pump motor 39. ln the meantime, water has ceased to flow from the tops of the tubes through pipe 91 with the result that the temperature of bulb 97 has risen and switch 47 has reclosed. Thus, switch 47 provides the interlock circuit which holds solenoid 41 energized after the next freezing operation has restarted and the cycle is therefore repeated.

Referring to Figures 6 to ll of the drawings which show another embodiment of the invention, a pair of sheet metal shells 60 and 61 form respectively, a water inlet passageway 86 and a water discharge passageway 88. These shells are fabricated of sheet metal with soli gasket 80 on the inner surface of the end wall seals the openings. The shells are clamped in place by bolts (not shown) extending through a plurality of tubular brackets 82 welded to the sidewalls of the shells. The entire header is enclosed in foam rubber insulation 70 and the shells are spaced apart by strips of foam rubber 72.

The header 3-is provided with sixteen nozzles 100 which are positioned respectively, at the tops of the various freezing tubes. Each of the nozzles includes a water discharge pipe or tube 102 which is welded to the bottom of shell 60 and projects downwardly unsupported into the top of the freezing tube. Concentrically positioned around tube 102 is an overflow sleeve or tube 104 which is soldered in the bottom wall of shell 61 and has its upper end projecting above the center of the water discharge passageway 88 in this shell. The lower end of tube 104 projects into the top of the freezing tube and has an annular external groove 106 thereon from which is supported a target member 110 having a pairvof balelike arms 112 and a dish-like target portion 114.

Target member 110 is identical with the similar member 56-59 of the embodiment of Figures 1 to 5 and (see Figure 1l) the upper'ends of arms 112 are bent toward each other and are enlarged with arcuate end surfaces 116. These end surfaces are resiliently held against the bottom of the groove 106 and (see Figure 7) the sponge rubber member which forms part of insulation 70 presses resiliently against the tops of these arms 112, thus to insure that the target member will not become dislodged. Thus, the nozzle construction provides a water discharge passageway through tube 102, and the water is directed from this passageway againstthe stationary target member in the manner discussed above in connection with the embodiment of Figures 1 to 5.

An overflow discharge outlet is also provided by the annular space between the two tubes 102 and 104 through which water is discharged into passageway 88, but tube 104- extends upwardly into passageway 88 so that water does not flow in the reverse from this passageway into any of the freezing tubes. Passageway 88 is provided at its right-hand end with a vent pipe 108 which prevents abnormal pressure or vacuum conditions to build up in the passageway. The water supply pipe 90 which extends from the water pump is connected to the right-hand end of shell 60 thus to supply water to passageway 86 andthe water outlet or discharge pipe 91 is connected to shell 61 thus to receive the overflow water from passageway 88.

The operation of this embodiment is similar to that discussed above, it being understood that water under pressure in passageway 86 is discharged into the freezing tubes. At the end of the freezing operation cold water from one or more of the tubes ows upwardly through the respective tubes 104 and thence through passageway 88 into pipe 91 to initiate the harvesting operation. The concentric arrangement of the water supply and discharge passageways of the nozzles has advantages patricularly under some conditions of operation and with certain types of machines.

As pointed out above, in both of the illustrative embodiments of the present invention the overflow discharge passageway is vented to atmosphere; that is, in Figures 1 to 4 a vent 92 is provided and in Figures 6 to 9 a vent 108 .is provided. As stated, these vents maintain atmospheric pressure in the overow discharge passageway which, as indicated, are open to the tops of the tubes. It has been found that this arrangement has particular advantages with ice-making machines such as those of the illustrative embodiments. With such a machine the normal freezing behavior in the freezing tubes is that the water flows down the tube walls in an open free ow during the beginning of each freezing cycle. That is to say, the tube is not full of owing water, but there is a rapidly moving sheet of water covering the entire wall surfaces, and there is a column of air down the center of the tube.

As freezing progresses and the holes in the tubes become smaller, a point is reached in one or more tubes when there is a sudden bridging over so that the column of air disappears and there is no longer a free flowing layer of water; but rather, there is a solid column of water which occupies the entire opening at the center of the aromas Column of ice. This sudden bridging over effect tends to cause a partial vacuum condition to exist because the solid column of water tends to carry air with it so that the tube, in effect, acts as an aspirator. The partial vacuum condition is transmitted to the overow discharge passageway and through it to the tops of the other tubes, most of which may still have a column of air in them with the free ow of water down their walls. This causes air to ow back up the tubes which still have columns of air in them at that instant and the upward passage of air tends to interrupt the downward ow of water and water is carried with the air into the overow discharge passageway. At times this flow has been sufficient to initiate the harvesting cycle which, as will be understood, is pre `mature because none of the columns is frozen solidly and most of them have a substantial opening through them.

With the vent arrangement herein disclosed, the partial vacuum condition is relieved by the vent and, therefore. the partial vacuum condition in one tube is not transmitted to another. Thus, the mode of operation discussed above is carried on without danger of the freezing operation being stopped prematurely.

Under some circumstances, it is desirable to vary the sizes of the nozzles or otherwise to control the water ilow through them. In this way it is possible to insure uniform building up of ice where the freezing tubes are cooled at different rates. Thus, in the embodiment of Figures 1 to 5 there is a tendency` for the tubes at the two ends of the bank to be cooled more rapidly because of the cooling eiects of the bends at the ends of the runs of the evaporator sections. This non-uniformity of cooling of the tubes is compensated for by flowing water at a more rapid rate through the two end tubes than through the other tubes. Thus, the greater quantity of water flowing through these tubes carries away heat more rapidly, and ice builds up at a slower rate. It is therefore contemplated that the tlow be so adjusted in each tube as to give the desired rate of building up of ice; illustratively, the ow through each tube is somewhat proportional to the rate of heat transfer from that tube.

As many possible embodiments may be made of the mechanical features of the above invention and as the art herein described might be varied in various parts. all without departing from the scope of the invention, it is to be understood that all matter hereinabove set forth, or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim:

l. In ice-making apparatus of the character described a water distributor system which includes, a closed water supply header having outlets spaced along its bottom wall and adapted to project solid streams of water respectively into the tops of the various tubes of a bank, target means positioned in the tops of the respective tubes in the line of the water ow and adapted to divert the water outwardly and upwardly within each tube against the tube walls thereof, and venting means connected to the tops of said tubes and extending therefrom to substantially atmospheric pressure.

2. Apparatus as described in claim l which includes, an overow discharge header connected to receive overflow water individually from the tops of the tubes and providing said vent means therefor.

3. Apparatus as described in claim 1 wherein the size of the outlet is varied to control the flow to each tube with respect to the cooling rate so that ice builds up substantially evenly in the various tubes.

4. In ice-making apparatus of the character described, the combination of, a plurality of vertical freezing tubes which are provided with inner freezing surfaces which are refrigerated so that ice will form thereon to form ice bodies, and water distributor means to supply water to said tubes including a header and a plurality of nozzles connected to said header and associated respectively with said freezing tubes with each nozzle projecting into the Lipper end of its tube and having an unobstructed outlet which is circular in cross section and has its axis substantially concentric with the axis of its freezing tube, each of said nozzles including a deliector positioned in the top of the tube and formed by a plurality of supporting arms and a target portion which is substantially less in diameter than the smallest transverse dimension ot' the tube whereby there is a substantial free opening, and the water flow from said water distributor in the various tubes being controlled in substantially a direct relationship to the rate of cooling of each tube whereby ice builds up at substantially the same rate in each tube.

5. In ice-making apparatus of the character described, the combination of, a plurality of vertical freezing tubes which are provided with inner freezing surfaces which are refrigerated so that ice will form thereon to form ice bodies, a water discharge means connected to the top of each of the tubes and a vent to atmospheric pressure connected to said discharge means whereby abnormal pressure conditions in one tube do not substantially alter the operations in the other tubes, and water distributor means to supply water to said tubes including a header and a plurality of nozzles connected to said header and associated respectively with said freezing tubes with each nozzle projecting into the upper end of its tube and having an unobstructed outlet which is circular in cross-section and has its axis substantially concentric with the axis of its freezing tube, each of said nozzles including a detiector positioned in the top of the tube and formed by a plurality of supporting arms and a target position which is substantially less in diameter than the smallest transverse dimension of the tube whereby there is a substantial free opening.

References Cited in the file of this patent UNITED STATES PATENTS 250,912 Grinnell Dec. 13, 1881 759,623 Link May 10. 1904 1,021,566 Wood Mar. 26, 1912 1,427,822 Kennedy Mar. 1l, 1918 1,674,480 Nelson June 19, 1928 2,215,916 Dodd Sept. 24, 1940 2,239,234 Kubaugh Apr. 22, 1941 2,462,329 Mojonnier Feb. 22, 1949 FOREIGN PATENTS 28,415 Austria May 10, 1907 123,762 Germany Sept. 24, 1901

Images