US1885836A

US1885836A - Refrigerating apparatus and method of lubricating same

Info

Publication number: US1885836A
Application number: US295174A
Authority: US
Inventors: Herbert C Kellogg; Edward M May
Original assignee: Individual
Current assignee: Individual
Priority date: 1928-07-25
Filing date: 1928-07-25
Publication date: 1932-11-01
Anticipated expiration: 1949-11-01

Description

Nov. 1, 1932. H. c. KELLOGG ET AL 1,385,836

REFRIGERATING APPARATUS AND METHOD OF LUBRICATING SAME Filed Jui 25, 1928 2 Sheets-Sheet 1 Arr-00mm.

1932- H. c. KELLOGG ET AL 1,885,836

REFRIGERATING APPARATUS AND METHOD OF LUBRICATING SAME Filed July 25, 1928 2 She ets-.-Sheet 2 im m. a,

the liquid refrige lubricating the pump and Patent ed Nov. 1 ,1932

EEBBERT'C. KELLOGG Ann nnwn' M. May, or pnrnorr, mronremQnssrenons ro one: r. cowm, or nn'rnorr, MICHIGAN; canon a oownn nxncurnrx or sain GLEN P. CQWAN, EEGEASED BIGEBATING APPATUS AND METHOD OF LUBRIOA'I'ING Application filed July 25, 1928. Serial Ito. 295,174. 7

The invention relates to refrigerating apparatus in which a gaseous refrigeratin fiuid is cyclically condensed and liquefie and again evaporated from the liquid to the gaseous state with the accompanying absorption of heat. The improvements have to do more particularly with. the means for evaporating andin some ofitsaspects the invention has to do with apparatus in which the refrigerant is condensed and liquefied by a pump and condenser and with an improved method of any other working parts of the apparatus. g

OIae of the chief objects of the invention is the provision of a mechanical refrigerating apparatus employing an evaporator of the flooded type and a lubricant that is, to at least some extent,soluble in the liquid refrigerant employed and having improved means for maintaining a suitable body'of liquid refrigerant in the evaporator and returning accumulated lubricant from the evaporator to the refrigerant pump or condenser.

Another object of the invention is the rovision of a refrigerating apparatus emp oying an evaporator of the flooded type and a refrigerant in which the liquid lubricant is;

more or less soluble, which is adapted under varying heat loads, i. e., varying rates of 7 heat transfer, to maintain the lubricant in the evaporator at a relatively small and constant amount and at the same time to prevent discharge of refrigerant in the liquid state from the evaporator to the compressor.

A further object of the inven ion is the provision of an evaporator of the flooded-type havingan improved float valve for controlling the admission of liquid refrigerant to the evaporator, the valve mechanism, including the float, being bharacterized by simple construction, compactness, low cost of production, ease of servicing, and freedom from injury during handling and operation subsequent to the assembly of the apparatus.

Another object of the invention is the provision of an improved method of lubricating the working parts of mechanical refrigerating apparatus of the type employing a floodedv evaporator. I

rant to the gaseous state, 7

OFFIC- Other objects of the invention more or less incidental or ancillary to the foregoing will appear in the following description setting forth some of the preferred forms of con; struction and methods of carrying'out the invention, reference being had in the description to the accompanying drawings.

In the drawings, Fig. 1 is a more or less diagrammatic view in front elevation of refrigeration apparatus embodying the invention, the invention being shown in conjunction with a refrigerator of the domestic type. a

- Fig. 2 is an enlarged vertical cross section of the evaporator of the apparatus.

F ig. 3 is an enlarged fragmentary cross section on the line 33 of Fig. 2.

Fig. 4 is a vertical cross section of an-evaporator of modified construction.

Fig. 5 is a cross section on the line 55 of Fig. 6 is a vertical cross section of an evaporator of still another form of construction. 4

' Fig. 7 is a horizontal cross section on the line 7-7 of Fig. 6.

Referring in detail to the construction illustrated, and first to the form of the apparatus illustrated in Figs. 1, 2 and 3, 1 designates as an entirety an evaporator of the flooded type which is associated with a brine tank 2 to form a cooling unit which is shown mounted in the usual manner in a refrigerator 3 of the household type. 4 is a refrigerant compressor which may be of any suitable known form of construction and 5 is an electric motor by which the compressor is driven through belt 6. 7 is a condenser which may be cooled by water circulation or in any other known manner. A pipe or conduit 8 connects theinlet or suction opening of the compressor 4 with the discharge passage of the evaporator 1;-a conduit 9 connects the dischargepassage of the compressor with the condenser 7 and a conduit '10 connects the condenser 7 with the inlet of the evaporator 1.

The operation of the compressor in apparatus of this character is usually intermittent and in the construction illustrated it is controlled by an automatic switch 11 which maybe of any suitable known construction and which head 18a of the tube 18.

is actuated by the pressure of the gaseous refrigerant in the suction conduit8 with which the switch 11 communicates through conduit 12. '13 is the usual manual switch for throwing the entire apparatus into or out of operation. I

The resent invention has to do particularly with the construction and functioning of the evaporator 1. In theconstruction illustrated in Figs. 1, 2 and 3, the evaporator 1 comprises a shell 14 made of two sections 14a and 14b of sheet metal which are stamped or drawn into cylindrical cup shape and joined together by the horizontal flanged seam 15 which is brazed or soldered to render the joint gas tight. The top wall of the shell 14 is formed with an opening to receive a cast or forged fitting 16 which is brazed or otherwise permanently secured in the opening of the shell to form a gas tight joint between thefitting and the shell. The fitting 16 is formed with an opening 17 to receive a threaded refrigerant inlet tube 18 which depends within the evaporator. The joint between the tube 18 and the fitting 17 is rendered gas tight 'by the washer or gasket 180 of soft metal or other suitable material which. is clamped between the fitting 16 and a shoulder formed by the The said head 18a is formed with a threaded horizontal opening 186 to receive the end of the refrigerant conduit' 10.

A valve to control the passage through the inlet tube 18 is secured to the lower end of said tube. The valve comprises a body member 19 which fits nicely within the lower end of the tube 18 and is formed with a flange or shoulder 19a to engage the lower end of said tube. The valve body 19 is formed with an axial passage comprising an upper section 20 and a lower section 21 j of larger diameter.

, The shoulder 22 between the two sections of the bore serving as a seat for a needle valve 23 which is formed from stock approximately triangular in cross sect on and has a depending stem 23a of reduced diameter. A

- flanged and threaded fitting 24 engages the threaded lower end of the tube 18 and serves to secure the valve body 19 tightly in position in the lower end of the tube and also secures the needle valve 23 in the valve body, with the ass stem 23a of the valve projecting downward through a hole 24a in the lower end of the fitting24. said hole being larger than the stem so'that liquid flowing through the tube 18 and passing the valve 23 has free outlet through the lower end of the fitting 24. The upper end of the valve body 19 has a reduced extention or nipple 19b to which is secured a tubular metal gauze filter 25.

The valve 23 is controlled by afloat which is designated as an entirety by 26. This float is in the form of anlopen-topped annular cup of relatively large diameter.

As shown in Fig. 2, the float comprises a liquid tight joint 260 between the members 26a and 26b. The tube 268 is of adiameter to fit loosely on the depending tube 18 so that the latter serves as a guide for the float.

-A strip of metal 26d is brazed or soldered to the under side of the float so as to extend across the lower end of the tube 261) and engage the lower end of the valve stem 23a to press the valve upward against its seat when the float is lifted.

The fitting 16 is formed with a second opening 27 which is tapped at its upper end to receive an elbow fitting 28 to which in turn is connected thC SllCtiOil conduit 8.

In the lower end of the opening 27 a depending tube 29 is secured with a gas tight joint. The tube 29 has its lower inlet end disposed near the bottom of the annular cup shaped cavity of the float 26. As illustrated in Fig. 2 the evaporator shell co tains a body 30 of liquid refrigerant, or more strictly speaking of combined refrigerant and lubricant.

The shell 14 of the evaporator projects downward through an opening in the upper wall of the brine tank 2 and is secured to the tank by brazing or the like. The brine tank 2 may be formed as shown with a reentrant chamber to receive trays 2a, 2a for freezing water or foods. The tank2 is'filled with brine 26 up to a level somewhat below the top wall of the tank and so as to submierge the lower part of the evaporator shell 1 The evaporator, as well as the other parts of the apparatus, is adapted for the use of various refrigerants among which may be mentioned by way of example sulphur dioxide, methyl chloride and ethyl chloride. Lubricating oils which are suitable for the lubrication of the compressor are more or less soluble in most if not all of the preferred and commonly used refrigerants such as those mentioned. Thus suitable mineral oil lubricants are partially soluble in sulphur dioxide and are completely soluble in methyl chloride and ethyl chloride, at least within the limits of the proportions of oil and refrigerant normally employed. On account of this solubility, the liquid lubricant which is scrubbed past the compressor piston and is discharged into -the condenser, dissolves in the refrigerant liquefied in the condenser and passes with the latter in solution into the evaporator. Then when the refrigerant is evaporated the oil is left and accumulated in the evaporator so that provision must be made for its return to the compressor.

Assuming that the appuatus has been assembled and a suitable amount of refrigerant, such for example as sulphur dioxide, together with a suitable amount of lubricant,

such for example as a suitable mineral oil,

have been suitably charged into the system, the operation of the apparatus is as follows. Heat absorbed through the wall of the evaporator causes evaporation of liquid r frigerant therein with resultant rise of the pressure in the evaporator and in the return or suction conduit 8, which rise in turn causes the operation of the switch 11 to close the electric circuit and start the operation of the compressor 4. The'comp'ressor draws the gaseous refrigerant from the evaporator thus reducing the pressure therein and increasing the rate of evaporation of the liquid refrigerant in the evaporator. When the level of the liquid in the evaporator falls as a result of the evaporation, the float 26 is lowered and the valve 23 permitted to move away from its seat and admit additional liquid refrigerant, the float thus serving to automatically maintain a nearly constant amount of liquid in the evaporator. The evaporation is, of course, accompanied by the usual cooling effect upon the evaporator and the surrounding space cooled by it,

which in the case illustrated is the brine tank and the interior spaceof the refrigerator 3.-

stitutes the usual cycle of operations of apparatus of this general character.

However, the detailed operation within the evaporator during the cycle is quite distinctive and, as far'as we are aware, peculiar to our improved form of apparatus. When the operation of the compressor is started it begins at once to reduce the pressure in the, evaporator with resultant starting of relat vely rapid evaporation Within the mass of vthe liquid refrigerant .in the evaporator.

This evaporation is accompanied by the formation of bubbles of gaseous 'refr'gerant within the mass of the refrigerant which havethe efi'ect of raising the level of the liquid in the evaporator, this effect being most marked at the beginning of the operation of the compressor because .it takes an app ciable amount of time for the bubbles formed in the lower part of the mass of refrigerant to rise through the liquid and escape from its upper surface. Consequently when the 'compressor is first started the level of the liqud in the evaporator rises to a maximum for a i brief interval and then after the escape of gas from the surface of the liquid has started, the average level of the agitated boiling liquid falls to approximately the normal level of the liquid when refrigeration is not oing on, but the highest parts of, the agitate surface'of the liquid remain considerably above the said normal level. Thetempor'ary rise of the level of the boiling liquid to a maximum height before the gaseous refrigerant begins to escape from the surface of the liquid'is? naturally more marked where the depth of the body of liquid refrigerant in'the evap' orator is relatively greatso that a longer interval of time is required forthe. gas formed inthe lower part of the body of liquid tq rise through said body and escape from its upper surface. (This will appear more clearly when the construction shown in Fig. 4: is described. in detail). The float 26 has its height so de-' termined in relation to its weight that it is: adapted to maintain a normal levelof theliquid in the evaporator such that the in crease in the volume of the boiling liquid at the beginningof the operation of the compressor will carry thev level of the liquid up nearly to or even somewhat above the top rim of the float. If the level of the liquid is thus carried above the rim ofthe float it is; clear that some of the liquid will spill over into the float, and be drawn through the tube 29 and suction conduit 8 back to the compressor. This latter actiou'is more particularly feasible and desirable when a refrigerant is employed in which the lubricant is only'partially soluble and which is of reater specific gravity than the lubricant so t at the excess lubricant accumulating in the evaporator rises and forms a distinct stratum at'the' top of the body of liquid so that oil only spills over into the floatpn the temporary rise of the liquid level as above described. By properly proportioning the height of the float above the normal liquid level (that is thelevel when evaporation is nqt going on), for a given. depth of liquid refrigerant in the evaporator and a-given heat load, the rise of the li uid refrigerant underlying the stratum of In ricant to a level'above the rim of the float is avoided while only excess lubricant accu--' mulated infthe evaporator is discharged into the float and returned to the compressor' in the manner" described. When a refrigerant and a lubricant are used that are mutually soluble in all usable proportions thereof, it is preferable that the maximum liquid level at- .tained be somewhat below the rim of the float. However, whether themaximum liquid level be above or somewhat below the rim of the float, a discharge of'lubricant into the float...

and thence back to the compressor is attained in a manner wh ch Wlll nowbe explained. Assuming, for example, that thercfrigerant is sulphur dioxide and that the lubricant is a suitable mineral oil of lower specific gravity than the liquid refrigerant, with the normal liquid level in the vaporizer chamber 14 somewhat, above the middle of the float, as indicated by the line wm in Fig.

2, when the compressor is started and evaporation begins in the evaporator, 1f the float has been designed to secure overflow of lubricant into the float, the increase in volume of the liquid therein due to submerged bubbles will raise the liquid level temporarily slight- 1y above the rim of the float so that some of the stratum of oil floating on the liquid S0 will flow into the float and be drawnby the suction of the compressor through the tube 29 and conduit 8 back to the compressor, as previously described. Then as soon as the hub-- bles of gasified refrigerant be in to break through the surface of the liquid, the average level of the liquid will fall again approximately to the normal level w.'v, though by reason 1 of the agitation of the liquid the uppermost surface thereof attains somewhat higher levels. Thereafter, as eva oration continues, the bubbles of gasified re rigerant break through the surface of the liquid forming a mass of bubbles or foam which may build up around the float until it rises above the rim thereof whereupon some of it is carried over into the float from which it is drawn by the compressor in the manner previously described.

When the liquid refrigerant and the lubricant employed are completely mutually soluble, as where me. hyl chloride,for example,and a suitable oil are used, we ordinarily prefer so to design the float that the maximum level which the liquid attains during ebullition is slightly below the rim of the float. In this case as the bubbles formed by the gasified refrigerant rise through the body of liquid and emerge from the surface thereof they form a mass of bubbles or team which builds up around the float until it rises alcovev the rim thereof, whereupon some of it is carried over into' the float in the manner previously described and is drawn back to the compressor. In this manner there is passed over the rim of. the float liquid which consists chief-. ly of the liquid forming the walls of the hubbles and which is practically all lubricant since the liquid refrigerant does not have sufficient viscosity and surface tension to form the walls of the bubbles breaking through the surface of the liquid in the manner described. In other words, the-formation of the bubbles incident to the evaporation appears to have a selective effect upon the oil with its resultant separation from the mass: of the li uid. Furthermore, any slight amount of liqui refrigerant that may be dissolved in the lubricant forming the-foam has ample opportunity to evaporate before it enters the oat and is drawn out throu h the suction tube 29.

It is to be un erstood that the apparatus" can be operated in the manner last described with the maximum liquid level below the rim of the float when sulphur dioxide-and oil are employed as well as when refrigerants such as ethyl chloride and methyl chloride are employed; indeed we ordinarily prefer to so operate the apparatus regardless of the refrigerant usediwhen the bath of liquid refrigerant in the evaporator is relatively shallow, since in such cases the momentary rise of the liquid level at the beginning of the evaporation is not greatly above the level maintaine as the evaporation continues.

A variation of the above described operation that occurs under some conditions is to be noted. That is to say, where a refrigerant is employed in which the lubricant has a limited solubility, and particularly when active evaporation is not going on, bubbles from time to time rise through the liquid in the evaporator and burst through the surface of the liquid with more or less explosive 'force and project small quantities of lubricant upward from the said surface. Some of the lubricant thus thrown up from the surface of the liquid falls over into the float and thus finds its way back to the compressor.

It will be observed that the refrigerant evaporated from the bodyofjliquid in the evaporator, in being drawn from the evaporator, first passes over the rimof the float and into the latter from whence it is withdrawn tutes what may be considered the primary inlet opening of the discharge passage of the evaporator. Since the float rim has a very long perimeter, in comparisonv with the circumference of the discharge tube 29, the veloeity of the gas flowing over the rim and into the float is relatively low. This is a feature of some importance since it obviates e11- trainment by'the gas of the boiling liquid which attains levels nearly up to the rim of the float. Such entraining effects of a stream of gas upon a liquid are quite marked where the velocity of the gas is high, as is evidenced by the fact that the action of the gas entering the lower end of the tube 29 at relatively high velocity is to keep the float practically completely empty of liquid notwithstanding the faetthat the lower end of the tube 29 is substantially above the bottom of the float. It

is obvious that the long perimeter of the float rim makes it possible for a relatively large amount of lubricant to flow into the float quickly even if the level of the lubricant is raised but a little above, the rim. The large diameter of the float has another bearing upon the withdrawal of lubricant from the evaporator in that the correspondingly large area of the opening in the top of the float presents ample opportunity for the lubricant thrown up by bubbles breaking through the surface 0 the liquid .while relatively little evaporation is occurring to fall into the float in a manner previously described.

In Fi I s. 4 and 5 we have shown a modified form 0 the evaporator ofthe system, the same being designed more especially for-the assesses use of a refri erant such as sulphur dioxide in which the ubricant is incompletely soluble. The evaporator in this modified construction comprises a cylindrical shell 31 with a fitting 32-permanently secured 1n its top wall to receive a refrigerant inlet tube 33, having at its lower end an lnlet valve 34 that carries a strainer. 35. The fitting 32 also carries a depending discharge tube 36 and an elbow- 37-to receive the suction conduit leading to the compressor. Except n the case of the cylindrical shell 31 WlllCll Wlll be further described below, the construction ofthe above mentioned parts of this modified form ofevaporator is substantially the same as the construction of the corresponding parts of the evaporator first described and they need not therefore be described in further detail. An open-topped cylindrical float 38 is disposed within the shell 31 in concentric relation to the depending inlet tube 33. The float 38 differs from the float of the first described evaporator in that that through said holes to the lower end of the.

discharge tube 36. In addition to the modified construction of the float 38 the construction of this second evaporator further differs from the first one described in having its cylindrical shell .portion fitted with a series of depending U-shaped tubes 39 which serve to largel increase the surface of-the evaporator; ach of these'depending tubes has its open upper ends projecting through and hermetically secured in openings in the bottom wall of the shell 31 so that the liquid refrigerant intheevaporator fills the depending tubes as clearly indicated in Fig. 4. The evaporator contains abody 40 of liquid sulphur dioxide with more or less lubricant dissolved therein and with a stratum of excess lubricant floating at the top of the body, as previously explained. With the liquid standing at a normal level indicated by the line :v'o:, the float is so designed that the level of the liquid is raised at the beginnin of evaporation materially above the rims o the lower wall arts 38b of the float andthen when the bubbles be in breaking through the surface of the liquitf the average level of the liquid will fall again to approximately the normal level wa thus effecting an overflow into the float of some of the top stratum of the liquid.

rator, for the use of back to the compressor.

liquid in the eva of the mass passes over into it is drawn back to the compressor.

' 38a and corrcspon In the operation of the system embodying this modified form ofevaporation, when the evaporation begins there is a very marked raisin of the level of the liquid in the evaporator ecause the relatively-great depth of the liquid lengthens the time required for bubbles forming in the lower part of the body of liquid to dislod e themselves from the walls of the depen ing tubes and find their way upward through the liquid to the surface thereof.- As a increase in the volume of theliquid bodyis result the temporary correspondingly greater than where the y of the liquid is relatively shallow. The conditions are therefore somewhat more favorable, than in the case of the shallow evapolevel of the liquid to sheet an overflow of the lubricant into the float, whence it is drawn Following the initial rise the formation 0 amass of bubbles or foam on the surface of the liquid in the manner previously described in connection with the first form of construction and when the mass of bubbles orfoam rises to of the float on the low sides thereof some the float whence The formation of the float, with side wall I having diametrically opposite high sections ing diametrically opposlte low sections 382) is provided because of the marked agitation of the liquid in the evaporator. directly abovethe upper ends of the depending tubes 39. To prevent this marked agitation causing both liquid refrig erant and lubricant being thrown into the walls of the float are carried float, the side to a greater height in the regions of the tubes 39 than in the intermediate regions, the resultant high sections 38a of the float serving as guiardsor shields for the purpose This marked agitation above the stated.

tubes 39 is found to have the efi'ect of forci much of the stratum of oil that would otherwise overlie the region of the tubes circumiina an or the orator the ebullition causes the temporary rise in the edge or rim ferentially around the float to the regionsadjacent the low sections 381) of the float where there is less a tation with the result that the stratum of In ricant in the latter region is for the time being increasedin depth y reason of this greater depth of lubricant and there is less liability of liquid refriger- Ent tpassing over the low rim sections of the ca v In some of its aspects our invention is not limited to the discharge of the gasified re-f frigerant and of the excess lubricant through the float. Furthermore, some of the advantages of our open type of. float can be had with the float inverte and its open side submerged. The significance of these ,st'atements .will be better understood from a consideration of still another form of evaporator construction which is shown in Figs. 6 and 7.

In this last. mentioned construction the evaporator has a cylindrical shell 41 formed in two sections as in the case of the first described construction. The top of the shell has an o ning in which is hermetically secured a filiing 42 to receive a depending inlet tube 43 which carries at its lower end an inlet valve 44 which in turn carries a filter 45, the construction of the depending tube, valve and filter being substantially the same as in the corresponding parts of the previously described evaporators. Surrounding the depending tube 43 is an inverted annular cup-shaped float 46. This float has a metal strip 46a secured to the lower end of its cylindrical tubular part so as to engage the stem of the valve proper and press it against its seat when the float is lifted.

The upper wall of the shell 41 has a second opening to receive a fitting 47 which carries a dependin discharge tube 48 and an elbow 48a adapte to connect with the suctlOIi conduit leading to the compressor. Belowthe fitting 47 is an open-topped receptacle 49 which is roughly crescent shape or kidney shapein horizontal outline and which is suspended from the fitting 47 by a su port 50. theposition of the receptacle 49 being such that the lower end of the tube 48 is somewhat above the bottom of the receptacle.

In the construction illustrated, the evaporator shell 41 is mounted in the top wall of a brine tank 51 with the lower part of the evaporator shell submerged in the brine in said .tank,.th e brine tank being in detail of {1x125 suitable construction. 52 indicates a y of liquid refrigerant or combined reffii iarant and lubricant in the evaporator s e orator the admission of refrigerant in evaporator shell is controlled by the float valve in the manner previously described.

The open bottom side of the float being submerged, the float has ample buoyancy. With the accumulation of pressure in the evaporator shell the liquid tends to rise in the float cavity above the bottom edge. of the float but not to as high a level as the liquid attains outside of the float. Some evaporationof the liquid refrigerant occursdirectly beneath the float and some of the gaseous refrigerant thus formed finds its way upward into the chamber ofthe float thus insuring adeqliate buoyancy at all times.

T e open-topped receptacle 49 is so designed and positioned that when evaporation is going on some of the excess lubricant is discharged into'the receptacle to be returned to the compressor either by direct overflow of liquid into the receptacle or by the. d1scharge of the lubricant in the form of foam In the operation of the last form of evap to t e into the receptacle during the ebullition. In other words, the apparatus in so far as dis- :charge of lubricant and gasified refrigerant is concerned, is the same as in the other forms of evaporator. Thus, assuming that the normal level of the liquid refrigerant is as indicated in Fig. 6 at the line :r"a:", the height 'into the receptacle and, when the average level of the liquid falls back again to the normal level indicated by line a:"-w", from the discharge into the receptacle of lubricant in the form of foam caused by the ebullition. In the latter-case, on the other hand, use can be made of either a refrigerant in which the lubricant is only partly soluble or of one in which the lubricant is completely soluble and reliance is placed upon the discharge into the receptacle of lubricant in the form of foam formed by the agitation caused by the ebullition.

It will be apparent that in all of the forms of construction which have been described the return to the compressor of excess lubricant accumulating in the evaporator is effected by the same principle of operation. That is, the open-topped receptacle 49 in the case of the third form of construction, affordsan opening of large area bounded by a rim of large perimeterjust as do the opentopped floats 26 of Fig. 2 and 38 of Fig. 4, so that in alLcases there is a primary inlet opening for the suction conduit (formed by the rim of the float or of the rece tacle 49, as the case may be), and the secon ary inlet opening of the-suction conduit (the lower end of the tube 29 in Fig. '2, the lower end of the tube 36 in Fig.4 and the lower end i of the tube 48 in Fig. 6) is disposed in all cases at a point relatively remote from the v 3 said primary opening. Consequently, as has been explained in connection with the first form of construction, the gasified refrigerant when withdrawn from the evaporator does not. have suflicient entraining action the receptacle 49 of theQlast form of construction, the remoteness of the secondary discharge opening of the suction conduit from the said rim insures that there shall be ample opportunity for'the. evaporation orator.

\ reeaese of such liquid refrigerant before it passes out of the evaporator. It is obvious that from the functional standpoint, the float 26 of the. first evaporator and the float 38 of the I second evaporator serve notonly as floats but also as receptacles to perform-the function of the receptacle 49 of the third evap- In connection with the foregoing description and certain of the claims it will be unopenings of prior evaporators which have commonly been comparable in size to the refrigerant discharge duct and, of course, the

terms are used with regard to the previously explained functions performed by the large primary inlet of the discharge conduit, as well as the obvious function of readily and effectively receiving the lubricantlifted, in the ways above described, by eva oration occurring in the body of the refrigerant.

In each of the forms of construction described the temporary rise of the liquid level in the evaporator at the time the compressor is started is essentially'due to the establishmentof a substantiahtemperature difilerential between the liquid refrigerant and the substance to be cooled thereby, with the resultant vigorous evaporation of refrigerant. That is to say, when the compressor is started it quickly reduces the pressure in the evaporator and permits the sensible heat of the liq-uid refrigerant to cause a rapid evaporationof a part thereof with resultant rapid or sudden lowering of the temperature of the liquid refrigerant below that of the surrounding substances which are cooled in the normal operation of the apparatus. It is the formation of bubbles in the liquid refrigerant by this rapid or sudden evaporation of'a portion of the liquid that causes the temporary rise of the levelof the li uid refrigerant. Substantially .the same e ect would be secured if the temperature diflerential between the liquid refrigerant and surrounding substances to be cooled were otherwise eflected. For example, if in the household refrigerator illustrated in the drawings the doors were opened and a sudden blast of very warm air were admitted into contact with the evaporator, the tem- 'rature diflerential between the air and the en of the evaporator, on the one hand, might be suficiently great, without any diminution of the vapor pressure in the evaporator, to cause a sudden temporary evaporation of the refrigerant with resultant in crease of the temperature of the refrigerant to a value more nearly equal to that of the surrounding air. This sudden, temporary ebullitionof the refrigerant would cause a temporary rise of the refrigerant level in the evaporator just as in the case of the starting of the compressor. In the latter case the temperature of the liquid refrigerant is suddenly lowered in relation to the temperature of the surrounding air while in the other case the temperature of the surrounding air is suddenly increased in relation to the temperature' of the liquid refrigerant; and in both cases the sudden ebullition of the refrigerant with resultant temporary rise of the liquid level in the evaporator is due to the temperature. diflerential established.

From what has been said in'the foregoing description it will be apparent that the height to which the side Wall of the float or other receptor should rise above the normal, quiescent level of the liquid in the evaporator in order to insure separation of the lubricant from the liquid refrigerant and discharge of the separated lubricant from the evaporator, must be determined, in the design of any specific apparatus, in relation to other factors which will varyfor different designs. As noted earlier inathe descri tion, such factors include particularly t e relative depth of the liquidv refrigerant in the evaporator and the heat load (rate of heat transfer) to be carried by the evaporator. The heat load, in turn, depends upon the size or area of the evaporator walls contacted by the liquid refrigerant, the capacity of the compressor, etc. When the heat load is to be widely variable, the-maximum'rate of heattransfer is, oil course, 'to be taken into account in deter ining the height of the float (or other. receptor) walls, as well as to give'the desired result without affecting other parts of the apparatus, even in the case 7 where the float constitutes the receptor, -be-' cause no nice calibration of the float is re quired and its weight is so small, on account of its open, thin-walled construction, and its buoyant capacity accordingly so great that considerable increase in the weight of the float due toincreasing the height of its walls will always leave it with ample buoyant capacity. In such trial of a newly de signed evaporator the functioning of the oil return can readily be checked by making a short section of the evaporator discharge line of suitable glass tubing, the passage of oil or of mixed oil and 1i uid refrigerant being clearly visible and distinguished through the glass wall of the tube.

, It is to be observed that the mechanical agitation of the liquid inv the evaporator during evaporation, particularly in the uppermost stratum of the liquid, varies with the amount of oil in the liquid, the mechanical agitation due to the bubbling being greater when the proportion of oil present is greater. Thus, there is in effect an automatic control of the rate of discharge of lubricant from the evaporator, because when the amount of lubricant in the evaporator increases the resultant increase in the mechanical agitation due to the ebullition increases the rate at which the mass of bubbles or foam consisting of lubricant and gas forms and builds up from the surface of the liquid and, consequently, the rate at which excess lubricant is discharged into the float or other receptacle. Our improved method of separating the lubricant from the refrigerant m the evaporator anddischarging it from the evaporator to be returned ,to the compressor,

by taking advantage of the inherent varia-- tion in the rate of foam formation with varying proportions of lubricant, enables us, under all working conditions, that is, under varying rates of heat transfer, with our improved apparatus to maintain a relatively low percentage of lubricant in the evaporator without risk of discharging liquid refrigerant from the evaporator along with the lubricant. This is true both in the case of refrigerants, such as sulphur dioxide, in which lubricant is partially soluble and also in the case of refrigerants, such as methyl chloride and ethyl chloride, in which the lubricant is more highly or completely soluble. Thisis a matter of very considerable practical importance. Thus, when a refrigerant such as sulphur dioxide is used we are enabled to operate the evaporator with -a relatively thin stratum of lubricant on the refrigerant and largely avoid the difliculty incident 'to a thick stratum of lubricant,

" namely, that the theoretical pressure-temperature relation of the refrigerant is seriously modified so that the compressor must run with a lower suction pressure to produce a given temperature in the evaporator, which means a lower capacity and a lower efliciency for the compressor. Also, it is obviously impossible to rely upon the theoretical pressure-temperature relations of the refrigerant in setting the pressure operated switch which controls the, operation of the compressor to I maintain the desired temperature in theevaporator. Furthermore, the very fact that our improved method and apparatus maintains a lower concentration of lubricant in the refrigerant lowers. the Variation of the concentration, thus rendering the'pressure-temperature relation of the liquid in the evaporator more constant. Similarly, when use is made of refrigerants, such as methyl-chloride, in which the lubricant is fully soluble,

the low concentration of lubricant which We are able to maintain 1n the evaporator avoids Furthermore, as in the case of pressure-temperature relations for the liquid in the evaporator.

.Our improved type of float, whether of the open-topped or open bottomed form, has: the

marked advantage that its buoyancy is af- N fected to a minimum extent by variations in the specific gravity of the liquid in which it is partially submerged. This is due to the fact, that the float has upright cylindrical sides so that when the specific gravity of the liquid is reduced by the ebulition the increased depth of the submergence of the float is taken advantageof to a maximum extent to compensate for the lower specifie'gravity of the liquid. This would not be the case if the float had the spherical or horizontal cylindrical sides such as have been commonly used heretofore. Furthermore, our improved form of floathas relatively great buoyancy and lifting power. This is due to several things. .It is due in part tothe fact that the float is immersed partly in gas and partly in liquid, that is to say, in two fluids ofwidely different specific ravities, whereas in the case of the closed f oats of spherical or horizontal cylindrical form'heretofore commonly used in flooded evaporators for controlling the level ofthe liquid sulphur dioxide refrigerant upon Which'the excess lubricant floats, the float has been immersed partly in the liquid sulphur dioxide and partly in-the 1 stratum of oil floating thereon, the specific gravities of these twoiliquids differing relativelylittle from each other. The relatively great buoyancy of our float is further due to thefact that the float can have a large dis- 1 placement volume and .yet be relatively light. in weight. This is possible because the float is open and its walls are never subjected, as

are closed floats, to unbalanced gas pressures in the evaporator, so that the walls can be made of relatively thin metal. This is a mat- .ter of considerable importance when it is considered that the gas pressures in such evaporators vary all, the way from about 14 pounds below atmospheric pressure when the system is being exhausted preparatory to charging with refrigerant upward to about pounds above atmospheric pressure when the evapo rator is subjected to summer temperatures during shipment. 7

It will readily be appreciated that the use of a simple cup-shape float, f'that can be formed from relatively thin sheet metal, to control the inlet of liquid refrigerant to the evaporator provides a construction that can thus removed from the float-is lubricant, it is be produced at very low cost. This is rendered feasible by the arrangement of the gaseous refrigerant discharge tube in such a way that the suction of the compressor will remove any liquid that finds its way into the float. While, in the normal operation of the preferred form of the invention the liquid to be observed that under some conditions the liquid to be removed from the float may be refrigerant alone. For example, in the shipment of apparatus of this character charged with refrigerant, the liquid refrigerant in the evaporator is practically certain during shipment, and before any lubricant may have entered the evaporator, to be splashed into the cavity of the float and when the apparatus is first placed in operation the suction of the compressor-serves to quickly remove this liquid refrigerant and permit the float to operate in its normal manner. Accordingly the advantage of the construction is not limited to the removalof lubricant from the evaporator.

The float valve also is exceedingly simple in construction and reliable in operation. It

will be observed that thedepending inlet tube,

the float valve carried by the lower end of the said tube and the filter which in turn is carried by the body of the valve, are assembled as a unit and can with the greatest ease be inserted into and removed from the evaporator shell as a unit. This very greatly facilitates the servicing of the evaporator. The fact that with our improved form of construction the float has no positive connection with the needle valv'e,-as by links, levers or the like,

both reduces the cost of producing the parts, facilitates their assembly, and minimizes wear and tear and the corresponding troubles in operation. However, it is to be observed that insofar as some of the broader aspects of the float construction are concerned, the invention is not limited to a construction in which the float actuates the valve directly without the interposition of an arm or lever.

The casing or wall structure of our improved evaporator can be produced at low cost because of its marked simplicity, the wall proper consisting of but two parts 14a and 145 which are readily formed from sheet metal and which are permanently secured together by a soldered or brazed flanged seam that is readily formed. The use of this type of construction is feasible because'all parts of the valve mechanism, which are the only parts that are at all likely to get out. of order, can readily be removed from the evaporator in the manner explained above.

The very great compactness of the entire evaporator structure, particularly in the case of the first and second forms of construction, is obvious, a float of very great capacity being providedin an evaporator shell ofrelatively small size. This, among other advantages,

obviates the necessity of using a. large mass of refrigerant in the evaporator.

The form of construction shown in Figs. 6 and 7 of the drawings is not claimed specifically in the present application as it constitutes subject matter claimed incur 00 endingappli'cation Serial No. 351,372, filed arch. 30, 1929. Attention is also directed to our copending application. Serial No. 352,673, filed April 5, 1929, which relates to a form of construction in which the principles of the present invention are applied to evaporators of the horizontal header type.

In the foregoing description and in the drawings, we have presented some of the preferred forms of embodiment of our invention for purposes of explanation and illustration, but, from What has been said, it will be 'obvious that the embodiments of our improvements may vary quite Widely within the scope of our invention as defined in the appended claims. For example, it is obvious that the receptacle provided inthe evaporator to receive the separated lubricant and the discharge passage leading from the receptacle may, insofar as "the broader aspects of the matter are concerned, take a great variety of forms, the essential thing being the provision of a receptor to receive lubricant separated by the mechanical effect of the evaporation in the mass of the liquid refrigerant, together with means for drawing off the lubricant thus separated so that it can return to the compressor. Various other lines of modification might be pointed out, but it is believed that they will be entirely obvious to those skilled in the art.

What we claim is:

1. In the process of refrigeration in which a liquid refrigerant in a closed system is evap erant whereby lubricant escaping from the 1 pump into the condensing chamber dissolves in the liquid refrigerant therein and passes with said liquid refrigerant into the evaporating chamber; effecting separation from the liquid refrigerant in the evaporator of lubricant lifted above the normal level of the body of liquid in the evaporator by ebullition thereof, and conducting the thus separated lubricant out of the evaporating chamber back to the pump to lubricate the latter.

2. In the process of refrigeration in which a liquid refrigerant in a closed system is evaporated from a body thereof maintained in one chamber of the system, the gaseous refrigerant withdrawn into another chamber which comprises introducing into the closed system a liquid lubricant of lower specific gravity than'the liquid refrigerant and having a limited solubility in said refrigerant whereby lubricant escaping from the'pump into the condensing ,chamber dissolves in the liquid refrigerant therein and passes with said refrigerant into the evaporating chamher; effecting separation from the liquid refrigerant in the evaporator of lubricant lifted above normal level of the body of liquid in the evaporator by ebullition thereof; and conducting the thus separated lubricant out of the evaporating chamber back to the pump to lubricate the latter.

3. In the process of refrigeration in which a liquid refrigerant in a closed system isevaporated from a body thereof maintained in one chamber of the system, the gaseous refrigerant intermittently withdrawn into another chamber of the system and condensed therein, and then returned in liquid form to the first chamber at a reduced pressure, the method of lubricating the working parts of the apparatus which comprises'introducing into the closed system a liquid lubr cant of lower specific gravity than the liquid refrigerant and having a limited solubility in said refrigerant whereby lubricant escaping from the pump into the condensing chamber dissolves in the liquid refrigerant and passes with the latter into the evaporating chamber; effecting the intermittent discharge into the refrigerant outlet of the evaporating chamber of excess lubricant accumulated in said chamber when the level of the liquid in said chamher is raised by ebullition at the beginnings of the intermittent operations of the pump- 'ing mechanism without such discharge of liquid refrigerant; and conducting the discharged lubricant back to the pump to lubriin one chamber of the system, the gaseous refrigerant withdrawn into another chamber of the system and condensed therein and then returned in liquid form to the first chamber at a reduced pressure, the method of 1 lubricating the working parts of the apparatus which comprises introducing into the closed system a liquid lubricant of lower specific gravity than the liquid refrigerant and having a limited solubility in said refrigerant whereby lubricant escaping'from the pump into the condensing chamber dissolves in the liquid refrigerant and passes with the latter into the evaporating chamber; effecting the intermittent discharge into the refrigv erant outlet of the evaporating chamber of lubricant thus separated excess lubricant accumulated in said chamber when the level of-the liquid in said chamber is temporarily raised by ebullition due to the sudden establishment of a substantial temperature differential between the liquid refrigerant and the substance to be cooled thereby, without such discharge of liquid refrigerant; and conducting the discharged lubricant back to the pump to lubricate it.

5. In a refrigerant evaporator of the flooded type adapted to be operatively connected in a closed refrigerating system comprising an intermittently operating compressor and a condenser and in which system the workin parts of the apparatus are lubricated by liquid lubricant that is of lower specific gravity than the liquid refrigerant and-soluble to a limited extent therein, the combination of a casing having an inlet for liqu d refrigerant and means providing a discharge passage for gaseous refrigerant and liquid lubricant adapted to be connected with the suction side of the compressor of such system; and means for controlling admission of liquid refrigerant into the casing and maintaining therein a normal liquid level when the compressor is intermittently started causes a discharge into the said opening of liquid lubricant from the top of the body of liquid in the evaporator without such discharge of liquid refrigerant, whereby the rom the refrigerant in the evaporator is withdrawn together with the gaseous refrigerant through the discharge passage to the compressor.

6. In a refrigerant evaporator of the flooded type adapted to be operatively connected in a closed refrigerating system comprising an intermittently operating compressor and a condenser and in which system the working parts of the apparatus are lubricated by liqu d lubricant that is of lower specific gravity than the liquid refrigerant and soluble to a limited extent therein, the combination of a casing having an inlet for liquid refrigerant and a discharge duct for gaseous refrigerant and liquid lubricant adapted to be connectedwith the suction side of the compressor of such system; a receptacle in the casing having an inlet for lubricant and refrigerant gas of relatively long horizontal perimeter, the discharge duct of the casing having its'inlet opening d sposed in said receptacle; and means for controlling admission of liquid refrigerant into the evaporator casing and maintaining therein a normal liqu d level at a distance below the said inlet of the receptacle such that the intermittent rise of said level when the compressor is intermittently started causes dis- III prising an intermittentl operating compressor and a condenser an in which system the working parts of the apparatus are lubricated by liquld lubricant that is of lower specific gravity than the liquid refrigerant and soluble to a limited extent therein, the combinatill tion of a casing having an inlet for liquid refrigerant and a discharge duct for gaseous refrigerant and li uid Iubricant adapted to be connected with t e suction side of the compressor of such system; a receptacle 'in the casing having an inlet for lubricant and refrigerant gas of relatively long horizontal perimeter, the discharge duct of the casing havin itsinlet opening disposed in the receptac e at a point relatively remote from the boundary of the said inlet of the said receptacle; and means for controlling admission of liquid refrigerant into the evaporator casing and maintaining therein a normal liquid level at a distance below the said inletof the receptacle such that the intermittent rise of said level when the compressor is intermittently started causes discharge into the receptacle of liquid lubricant from the top of the body of liquid in the evaporator without such discharge of liquid refrigerant, whereby the lubricant thus separated from the refrigerant in the evaporator is withdrawn together with the gaseous refrigerant through the discharge duct to the compressor.

'8. In a refrigerant evaporator of the flooded type ada ted to be operatively connected in a close refrigerating system comprising an intermittently operating compressor and a condenser and in which system the working arts of the apparatus are lubricated by liquld lubricant that is of lower specific gravity than the liquid refrigerant and soluble to a limited extent therein, the combination of a casing having an inlet for liquid retrigerant and a discharge duct for gaseous retrigerant and'liquid lubricant ada ted to be connected with the suction side '0 the cornpressor of such system; a valve for controlling admission of liquid refrigerant into the evaporator casing; an open topped, cup-shape float connected to said valve to actuate the same, the discharge duct of the evaporator having its inlet opening disposed within the cavity of the float and'the said float being adapted to maintain in the eve orator a normal liquid level ate distance slow the rim of the float such that the intermittent rise of said level when the, compressor is intermittently started causes discharge into the float of liquid lubricant from the top of the body of liquid in the evaporator without such discharge of liquid refrigerant, whereby the lubricant thus separated from the refrigerant in the evaporator is withdrawn together with the gaseous refrigerant through the discharge duct to the compressor.

9. In a refrigerant evaporator of the flooded type adapted for use in refrigerating systems in which the working parts of the" apparatus are lubricated by liquid lubricant that is of lower specific gravity than the liquid in the liquid refrigerant, the combination of an eva orator casing having an inlet for liquid re rigerant and an outlet for gaseous refrigerant adapted to be connected with the suction side of a refrigerant compressor; a

receptacle in the casin having a top opening of large area; a discharge duct leading from the cavity of the receptacle to the outlet of the casing; and means for controlling admission of liquid refrigerant to the caslng and maintaining therein a normal liquid level at such a distance below the top opening of the said receptacle that when lubricant in the casing is lifted by ebullition f one the body of liquid therein it will fall in o the said receptacle separate from the liquidretrigerant in the evaporator, whereby the lubricant thus separated from the refrigerant in the evaporator is withdrawn with the gaseous refrigerant through the discharge duct to the com-.

PX'ESSOI. I 10. lln a refrigerant evaporator of the flooded type adapted for use in refrigeratingsystems in which the working parts of the apparatus are lubricated by liquid lubricant liquid refrigerant and soluble to at least some refrigerant and soluble to at least some extent "that is of lower specific gravity than the extent in the liquid refrigerant, the combination of an eva orator casing having an inlet for liquid refrigerant and an outlet for gaseousretrigerant adapted to be connected with the suction side of a retri erant compressor; 'a receptacle in thecasing aving a top opening of large area; a discharge duct leading from the cavity of the receptacle to the outlet of the casing, said duct having its inlet disposed at a point relatively remote from i the perimeter of the to opening of the said receptacle; and means or controlling-admission of liquid refrigerant tothe casing and maintaining therein a normal liquid level at a such a distance below the top opening of the 5..

said receptacle that when lubricant in the easin is lifted by ebullition from the body of liqui therein it will fall into thesaid receptacle separate from the liquid refrigerant 1n the evaporator, wherebythe lubricant thus separated from the refrigerant in the evaporator is withdrawn. with the gaseous reflooded type-adapted for use in refri erating systems in which the working parts 0 the apparatus are lubricated by liquid lubricant that is of lower specific gravity than the liquid refrigerant and soluble to at least some extent in the liquid refrigerant, the combination of an evaporator casing having an inlet for liquid refrigerant and an outlet for gaseous refrigerant adapted to be connected with the suction side of a refrigerant compressor; a valve for controlling the admission of liquid refrigerant through the said inlet; an open topped, cup-shaped float in the evaporator for actuating said valve, said float having its height proportioned to its weight to maintain in the evaporator a normal li'puid level at such a distance below the rim 0 the float that when lubricant is lifted by ebullition from i the body of liquid in the evaporator it will fall into the float separate from the liquid refrigerant in the evaporator; and a discharge duct having its inlet end in communication with the cavity of the said float and its discharge end in communication with the outlet of the evaporator casing, whereby lubricant falling into the float is withdrawn through said duct with gaseous refrigerant to the compressor.

12. In a refrigerant evaporator of the flooded type ada ted for use in refrigerating systems in which the working parts of the apparatus are lubricated by liquid lubricant that is of lower specific gravity than the liquid refrigerant and soluble to at least some extent in the liquid refrigerant, the combinamissi on of liquid refrigerant to the casing and maintaining therein a normal liquid level at such a distance below the top opening of the said receptacle that when lubricant in the casing is lifted by ebullition-from the body of liquid therein it will fall into the said receptacle separate from the liquid refrigerant ,in the evaporator, whereby the lubricant thus separated from the refrigerant in the evaporator is withdrawn withrthe gaseous refrigerant through the discharge duct to the compressor.

13. In an evaporator for refrigerating apparatus, the combination of a casing wall structure having an inlet passage for liquid refrigerant and an outlet passage for gaseous refrigerant; a valve for controlling the refrigerant inlet passage; an open-topped, cupshape float in the casing for actuating said valve; and a discharge conduit connected to the refrigerant'outlet passage and having its valve being removable from the evaporatorwithout removal of any of the wall sections thereof; an open-topped, cup-sha the casing for actuating said va ve; and a discharge conduit for gaseous refrigerant connected to the aforesaid outlet passage and having its inlet within the cavity of the float.

15. In an evaporator for refrigerating apparatus, the combination of a casing wall structure comprising a plurality of sections and having an inlet passage forliquid refrigerant and an outlet passa e for gaseous refrigerant; a valve within t e caslng for controlling the refrigerant inlet assage, said valve and its seat" being remova le from the evaporator without removal of any of the wall sections thereof; an open-topped, cupshape float in the casing for actuating said valve; and a discharge conduit for gaseous refrigerant connected to the aforesaid outlet passage and having its inlet within the cavity 16. In refrigerating apparatus, the combination of an evaporator casing having an inlet opening for liquid refri erant and an outlet opening for gaseous re rigerant; an inlet tube secured in the inlet opening; a valve controlling the passage through said tube; an outlet tube secured 1n said outlet opening; and-a float slidably engaging and guided by one of the said tubes andactlng when it rises to close the said valve.

17. In refrigerating apparatus, the combination of-an eva orator casing having an inlet opening for iquid refrigerant in its top wall; a depending inlet tube secured in said opening; a valve controlling the passage through said tube; and a float havin an opening slidably engaging the 'de en ing tube and having means for closing t e valve when thefloatrises.

18. vIn refrigerating apparatus, the combination of an evaporator casing having an inlet opening in its top wall; an inlet tube removablv secured in ,said opening; a valve controlling the passage through said tube; and a float having an opening slidably engaging the depending tube and having means depending tube and valve being removable as a unit from the evaporator independently of the said float.

19. In refrigeratingapparatus, the combination of an evaporator easing having an in- .for closing the valve when the float rises, said let opening in its top wall; an inlet tube removably secured in said opening; a valve aeeaeee controlling the passage through said tube; a filter in said tube; and a fioat'havin an opening slidably engaging the de en ing a tube and having means for closing t e-valve when the float r1ses,'said depending tube and valve being removableas a unit from the evaporator independently of the said float.

20. In refrigerating apparatus, the combi- 1 nation of an evaporator casing having an inlet opening in its top wall; aninlet tube removabl secured in said opening; a valve contro ing the passage through said tube;

" and an open topped cup-shape float slidably engaging the depending tube'and connected with the said va of the said float.

21. In refrigerating apparatus, the combination of anevaporator casin havin an inlet opening in the wall thereo an i et tube. removably secured in said opening; a valve controlling the passage through said tube; and a movable float having an operative connection with the said tube to do its movev ment and having means for c osing the said valve when the float rises, said tube and valve being removable as a unit from the evaporator independently of the said float 22. In refrigerating apparatus, the combination of an evaporator casing havin an inlet opening in the Wall thereof; an et tube removably secured in said opening; a valve controlling, the passage through said tube; a filter in said tube; and a movable float havin an operative connection with the said tu e to guide its movement and having means for closing the valve when the float rises,

said tube and valve being removable as a unit from the evaporator independently of the said float.

23. In refrigerating apparatus, the combination of an evalporator casing having an inlet opening in t e wall thereof; an inlet tube removably secured in said opening; a

valve controlling the passage through said tube; and a movable open topped, cup-shape float having an operative connection with the said tube to guide its movement and operatively connected'with the said valve to,

actuate the same, said inlet tube and valvebeing removable as a unit from the evapora-' tor independently of the said float.

In testimony whereof, we hereunto aflix our signatures.

- EDWARD M; MAY..

ve to actuate the same, said depending tube and valve bein removable as a unit from the evaporator in ependently HERBERT c. KELLOGG.