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i m LA m D 2,406,080 TESTING ASSEMBLY Filed July 18, 1942 ‘ l . 5 Sheets-She'et 1 Aug. J20, 1946. _ J. M. LAIRDJ TESTING ASSEMBLY 2,406,080 . Filed July 18, 1942 5 She'ets-Sheet 5 ,7; 7/0914? ~ 176 2.20 Aug. 20, 1946. ' ‘hm. LAIRD - ‘ i ' 2,406,080 TESTING' ASSEMBLY - Filed July 18, 1942 45W I‘ . . F 6'6 ' W,Q _ ' ' I . s Sheets-Sheet 4 ' , .J? 61’ _ h 'il Aug. 20," 1946; J. M. LAIRD 2,406,080 _ TESTING ASSEMBLY 5 Sheets-Sheet 5 Filed July 18, 1942 I r : I l f J60 _. '_1» . _ 2,406,080 I Patented Aug. 20, 1946 UNITED STATES ‘PATENT OFFICE 2,406,080 TESTING ASSEMBLY James Madison Laird, Charleston, W. Va. Application July 18, 1942, Serial No. 451,509 18 Claims. 1 This invention relates to improvements in heat ing and cooling devices in which desired tempera tures may be established and maintained. A feature of the invention is the provision of a simple and compact arrangement, including automatic controls, by which a pre-set tempera ture can be maintained. . (01. 257-3) ‘ 2 Figure 9 is an elevation of the evaporator unit. Figure 10 is an upright sectional view through the heat interchanger and the over?ow con trol units. , Figure 11 is a View illustrating an automatic controlling switch. Figures 1 to 4 show the general assembly of the apparatus, which has a frame constructed of ‘welded metal angle members It and supporting Another feature of the invention is the provi sion of an apparatus for testing instruments the" operating parts and closing panels in posi throughout a wide range of temperature above 10 tion.' . and below room temperature, together with con -As shown in Figure l, the front panel FP closes trol means for assuring maintenance of the in the front of the apparatus and has adoor CD at strument at a desired testing condition of tem ‘its upper end for permitting access to, and ad perature. ' justment of, certain control devices as described A further feature of the invention is the pro 15 hereinafter. Beneath this door is a gauge LG vision of means for economically employing a which indicates the pressure on the “low” side of refrigeration system in producing and maintain the refrigerating system. The rotatable handle ing low temperatures. _ BV controls a by-pass valve between the “high’? Still another feature of the invention is the and “low” sides of the compressor system. A ro 20 provision of means for producing low and high“ tatable electrical switch HS controls the connec temperatures, and including devices for ef?ciently tion ‘of electrical heating units. A main switch passing from low to high and high to low temper MS effects control of the current ?owing through all electrical parts of the system. A white pilot atures. A still further feature of the invention is the lamp WP and a red pilot lamp RP indicate oper provision of control devices for determining the ~ ation of the system under selected conditions, and operation of an apparatus for producing tempera the switches DS, RS and LS, respectively, con tures extending over a high and low range, with trol the dumping system, the refrigerating sys maintenance of a desired temperature within tem, and the liquid supply system. On the right hand side panel GP, as shown in Figure 1, is pro close limits. A further feature of the invention is in the 30 vided a lower screen VS through which air may provision of means by which the operation of a move under the action of a fan (described herein refrigerating system may be maintained within after) for cooling the heated internal parts of the close limits through observation of overflow when apparatus. A high pressure gauge HG is visible the evaporator attains a desired effective liquid through the screen for indicating the pressure on the “high” side of the refrigerating system. An level. With these and other features as objects in upperscreen WS likewise permits the movement view, as will appear in the course of the follow of air, and access is provided to a control screw ing speci?cation and claims, illustrative forms of LC-—a of an automatic control unit, as will be ' practicing the invention are shown in the ac described hereinafter. The top panel TP is provided with an ori?ce through which access may be gained to the mouths of the receptacle housing RH, into which the standard device SD and the device TD to be companying drawings, in which Figure l is a perspective view of the apparatus showing the front panel arrangement. Figure 2 is a vertical sectional view through the apparatus, substantially on line ,2—2 of Figure 3. Figure 3 is a vertical sectional view, substan tially on line 3-3 of Figure 2. Figure 4 is a rear view of the apparatus With 45 tested are inserted, so that these devices can be subjected to varying temperature conditions for inspecting and standardizing the device 'I'D. ' In Figures 2, 3 and 4, the assembly of a com the rear panel removed. . pressor unit including the motor CM and the Figure 5 is a conventionalized view showing compressor C is indicated, as well as the posi 50 tion‘given a condenser D, a receiver R. and a the conduit system and the associated parts. Figure 6 is a diagram of the electrical circuits. dehydrator DH in the refrigeration system, along Figure '7 is a top view of the testing receptacle with a fan FM which moves air through the housing with its cover and guard sleeves removed. condenser D, and through screens VS and XS Figure 8 is an upright sectional view substan tially on line B-8 of Figure '7. - - r - on opposite sides of the apparatus. The recepy aaoaoso 3 . tacle housing RH is shown as mounted adja cent the top of the apparatus, along with con duits and associated structures, as will be de scribed hereinafter. Figure 3 shows the hous return conduit 21. Any liquid refrigerant which is carried over in the conduit 26 is trapped in the heat exchanger X, and ?ows through a con duit 32 to the controller ‘0C. ing HC of one of a number of automatic control In passing from the refrigerating cycle to the heating cycle, in operating the, apparatus, the devices which are positioned for access through the front closing door CD, and the housing LC of a liquid control device having the adjusting screw L_C—a thereon. The conduit system employed in thi‘s'illustrated refrigerant liquid in the evaporator EB ‘can be discharged or dumped therefrom. For this pur construction is shown on Figure 5 The compressor C delivers hot gaseous refrig Verant into a valve connection 20, from which the _ gas can flow by conduit 2| into the condenser D, where it is condensed and forms awarm lique- > ?ed refrigerant which passes through conduit 22 into the receiver R. From the receiver ‘R, dur ing the normal operation of the refrigerating sys tem in its cooling cycle, the warm liquid re frigerant ?ows through'a conduit 23 having a de pose a conduit 35 leads from a low point of the evaporator E3 to the dump valve ‘DV. In prac tical construction, it is preferred to enclose a por tion of the small conduit 25 from the valve EV within the conduit 35, as shown in Figure 7, as "this protects such portion of the conduit 25 against any frosting on the exterior thereof and provides a simpler assembly. From the dump valve DV, the refrigerant can pass through con duit-36 back into the receiver R. A check valve '3‘! is provided in the conduit 36 to prevent high pressure gas or liquid from passing directly from the receiver R to the evaporator EB during nor mal operation of the refrigeration system. hydrator ‘DH ~therein vto ‘the middle chamber of "a heat exchange device X, whose internal'con s'truction is shown and described 'in connection In order to provide a control on theo'peration with Figure 10. From Figure 5 it will ‘be noted that this heat exchange unit X is mounted'at'an 25 of the refrigerating system ‘when it is starting and while it is operating at less than full-rated angle to the horizontal of, for ‘example, three capacity, a conduit 130 leads from ‘theoutlet or degrees withjthe warm liquid refrigerant enter pressure connection 29 of the ‘compressor C ‘to a ing at the upper vend of the middle chamber. ?lter 4| and thence to a'by-pass valve BV, which Heat exchange occurs with vrefrigerant "evapo when opened permits the gas to continue through rate'd'in evaporator EB, so that this warm ‘refrig a conduit 152 to a manifold '43 and thence to the erant .is cooled and then passes by conduit ‘2'4 inlet connection 28 ‘of the 'COITIPI‘GSSOI'I'C. ‘The ‘to .a solenoid-controlled valve EV ‘and thence by gauge HG is connected tothe conduit at for in a‘ small ‘conduit 25 of restricted ‘cross sectional dicating the pressure at the “high side” of the area'to the evaporator or boiler EB, preferably compressor C. The gauge LG is connected to'the with ‘employment of the duct 35 as described manifold 43 to show the pressure at the “low side” ' hereinafter and illustrated in Figure ‘7. ‘It will be understood that when'the‘temperature of liq uidiin conduit 24 has not beenreduced'by the heat exchanger X, to the temperature prevailing within the evaporator EB, a certain'amount 1of flash .gas is ‘formed at 'the eXitY'o’f "valve EV, ‘so that the mixture of ‘gas and liquid-‘refrigerant will move rapidly in ‘the small conduit ‘25, and thus be delivered into ‘the evaporator "EB quickly,’ of-the ‘compressor'iC. , q ‘The testing receptacle structure, shown as the housing RH in Figures 2 to "5, has an internal construction as set outin ‘Figures 7 vto '9. An outer closing wall lii'l‘receives the successive vlayers of corkiil and 'asbestosf52 to provide aheat-in sulating structure. Within the heat insulation is positioned a vessel 53 providing a central well ‘having a sump 54 with a drainage conduit E60. 45 Within this 'well' is ‘received the vevaporator vor ling effect ‘upon the liquid level formed in the boiler unit and 'its associated parts. ‘As shown in evaporator 'EB. ' Figure ‘8, when ‘the apparatus is to be employed 'The action of .the evaporator ‘EB ‘in-reducing wherewith "the valve EV has a sensitive control the temperature of the surrounding medium is for testing thermometers and the like, the evap accomplished by ‘the entry ofthe heat units into 60 orator is constructed as two separate annular chambers "55. A pair of cylindrical external this evaporator so that a portion of the liquid walls .56 have concentric internal walls v5'! spaced refrigerant content therein is vaporized. This therefrom to provide an annular chamber ‘for-re vapor passes off through the vlarge conduit “26 ception of the refrigerant ‘liquid, the endsof the (see also Figure 9) and passes ‘through a trap - LT from which entrained liquid can return to the conduit 26 and the evaporator EB; and then the vapor enters the left-hand end chamber of the heat exchanger X, and flows relatively up ward through the ducts thereof tolthe right-hand end chamber and thence through the conduit 2'! back to the inlet connection ‘28 and thus to the compressor (Llcompleting a refrigerant cycle of movement. ' ' ‘ The evaporator E-Biis of ?ooded‘ type, and is intended to maintain a substantially constant'liq; uid level during the course or its operation. ‘This . I liquid level is determined by an overflow connec tion-leading by conduits 30, ~32 into an "over?ow ‘ control chamber 0C which is provided with a plurality of heating ?ns. on its exterior, so'that he temperature of the controller 0C is nor mallymaintained above the temperature of the vliq'uid‘in the evaporator vEB. ,Upon evaporation of liquid refrigerant in ‘the controller DC, ‘the ‘ gas can pass by 'conduit'cl to the ‘general gas - chamber being closed by the annular ?anges 358 ' which are brazed or otherwise secured to provide a'tight shell. The supply conduit ‘25 for liquid refrigerant leads into ‘the conduit 135 having a branched connection or manifold ‘5'9 with. open ings 66 into the two-chambers '55 'e'ssentiall'yvat their bottoms. The annular space between the inserted portion of the conduitl2'5 and within the conduit \35 serves as a drainage conduit through which the liquid maybe drawn off from the an nular chambers 55 under “dumping” conditions, as described hereinafter. a Refrigerant gas formed within the chambers 55 isreturned to the compressor of the refrigerat ing system through the return conduit 26 ‘having the individual openings éIii into the chambers .55. The ‘maximum liquid level in the'chambers '55. is ‘controlledlbytheover?ow conduit 38 ‘which-‘has ports iii-2 into-thechambers. The two evaporator chambers‘55 are thus connected byithree inani folds both for fluid ‘now and f0r"meéha,?i(}a1ii11~ 2;406,080 tegration, and furthers'upports 63. may also be provided to assure a strong and rigid structure. Around the exterior'of theevaporator'structure is wrapped a helix 05 of tubing having its ends (Figures '1 and 8) carried outside the closing‘wall Liquid from the over?ow conduit 30 ?owsdirectly to the conduit 32 and thenceinto the overflow control device 00, and any liquidgathering in the end chamber 16 islikewise transferred into ' the, over?ow control device 00, so‘ that such liquid encounters the bulb 220 connected with the conduit 200 leading to the automatic liquid con 50 to provide an inlet portion 66 and an outlet portion 61. This coil 65 is employed for the pas trol LC (Figure 5). Since this liquid is at a low sage of a heat-exchange fluid under the condi temperature, the bulb 220 responds immediately tions set out hereinafter, more particularly in 10 by reducing the gas pressure Within the duct 200‘ connection with elements I50 to I51 in Figures and thus causing the liquid control LC to close ‘the valve EV and liquid no longer is delivered into 3 and 4. ‘ 1 . i The electrical heaterv elements HE, HF are il— the evaporator chambers 55 and therewith the . lustrated as located‘in insulatingsupports posi liquid level therein is maintained, save and ex‘ tioned alongside the sump 54 and beneath the cept as evaporation may occur. Therefore,‘ the bottom of the well 53, and as having the con system has a safety feature in that if the ?ow of ductor wires I29, I30, I33 extending thereto. The top of the well 53 is closed by a plate 68 liquid through the conduit 30 beinterrupedfor any reason, so that the desired maximum over ?ow level is not maintained in the chambers 55, a further automatic, control is effected when liquid which are of smaller external diameter than’the is brought over through the gas return conduit 26. inside of the walls 51 and have top ?anges for When the liquid entering the over?ow control de supporting :them on the plate 53; these guard vice OC cools the bulb7220, the liquid itself is heat sleeves 69 extend through the length of the units ed and gives off gas which can return through the and prevent. contact of the thermometer directly conduits 3| and 32 and reach the main return 25 with the walls 51 whereby to assure that the tem conduit 21. Furthermore, this liquid is also being perature applied to the thermometer will be that heated from the wall 82 which is being maintained of the liquid in th well 53, and also to avoid dam at a temperature higher than that of the liquid age to the walls by physical contact therewith. by theaction of the ?ns 85 which are exposed to The sleeves 69 are preferably apertured to assure the ‘temperature of the air within the general a free circulation of ?uid within the wells, where 30 housing provided by the closing panels‘ and such by the temperature therein may be maintained gas likewise passes off through the conduits 3I uniform and thus accurate determinations made. and 32; so that the overflow control device 0C is The internal structure of thepreferred ‘heat . soon cleared of refrigerant liquid and returns-to interchanger and overflowparrangement isshown 35 its original temperature, wherewith the bulb 220 having two openings therein concentric with the chambers 55, for receiving the guard sleeves 69 in Figures 5and 10.’ The heat exchanger has a cylindrical wall 10 which is sealed by end pieces ,‘II, 12 which may be brazed in position. Inter mediate header walls 13, 14 are brazed within the body 10 and sealed to the connecting tubes 15. again produces a pressure in the duct 200 to per mit a further in?ux of liquid to the chambers55. The electrica1 circuit connections are, conven tionally shown in Figure 6, in which the supply main I00 is connected through the main switch ‘ 5 The axes of the wall 10 andof the tubes 15 are 40 MS for controlling the refrigerating ‘system, with preferably inclined at an angle of, say, three degrees to the horizontal, so that there will be drainage through the structures.’ The heat in a conductor I02 leading to a contact of the refrig crating control device RC and from a second ter minal of this device a conductor I03 leads to the terchanger provides a left-hand end chamber 16, compressor motor CM and the fan motor FM, a central chamber 11 surrounding the tubes 15, 45 which are connected in multiple and by the con and a right-hand end chamber .18. The retum ductor I04 and the refrigeration switch RS back ing refrigerant gas enters the chamber 1-6 through to the supply main IOI. Thus, the operation of conduit 25, flows towardthe right within the the motors CM, FM is under control of the device ducts-15 to the end chamber 18, and then passes RC and the switch RS. 50 through conduit 21 back toward the compressor, Further a conductor I05 is branched from con-i thelgas serving to cool the tubes 15. Therela ductor I03 and extends through the liquid control tively hot liquid refrigerant, under pressure, en device LC to the solenoid I05 which operates the ters the central chamber 11v at its upper end control valve EV with a return by conductor I01 through the conduit 23, and ?ows downwardly and the liquid control switch LS to the conductor in this chamber around the tubes 15 and effects 55 I04 and thus back to the supply main _| 0| through a heat exchange therewith and by movement in direction opposite to the gas flow within the the switch RS. } p ‘ Further, the white pilot lamp WP is connected tubes; so that the refrigerant liquid is relatively between the conductor I03 and the conductor I01, cooled to avoid the formation of excessive ?ash so that it is under control of the switch LS and gas upon passage through the valve EV, and to 00 the control RC, and indicates at all times while cause a relative super-heatingof the refrigerat the system is in condition to effect refrigeration. :ing gas on its way back to the compressor. The For the transition between the cooling andvthe cool liquid refrigerant leaves the central cham heating ‘cycles, a circuit is established fromthe ber 11 through the conduit 24. In the event that supply main I00 by a branch of conductor I02ito liquid as such, or as bubbles or mist, is carried 65 a dump control manual ‘switch DS and by_,.con over through the .pipe‘ZGLinto the :end chamber ductor III to the solenoidy92 of the dump; control 10, it can ?ow downwardly through the pipe 32 valve DV, and thence by conductor 93 to a, contact into the upper end of the over?ow control 00, of the dump control device DC. From the, other which is ‘positioned vat ‘substantially the same contact of the device DC, the circuit is completed ‘ angle'as the heat i terchanger'X. This over?ow 70 by conductor 94 back to the supply main IOI. control device comprises altubular body 82 hav Thus, when the switch DS is closed and the device. ing the closing end walls 83, 84 brazed or other DC energized for closing, the dump valve DY, is wise sealed thereto. Surrounding the body are a .opened. , plurality of heat-?ns 85 closely engaged with this body and secured thereto for easy transfer of heat. - 15 Forjthe heating cycle, current ?ows‘ hfomthev 2,406,080 91 pressure therein; but it will be noted that the pressure in this manifold at which the corre sponding control device will be effective can be regulated by proper adjustment of the spring 2l2 of the particular control device. In operation, the well 53 is usually supplied with a liquid which maintains ?uidity and does not decompose throughout the range at which the testing is to be accomplished. A high boiling hydrocarbon, for example, may be employed at temperatures from 50 degrees below zero F. to 500 degrees above. The particular liquid can be selected with due regard to the temperature range to be covered, the absence of reaction by the liquid upon the structure or the apparatus to‘ be tested, etc. , 10 The temperature in the well 53, and of the liquid therein, is thus reduced to a point deter mined by the setting ,of the adjusting screw LC—a of the liquid control device LC. In the initial starting of the system, it is preferred to open the by-pass valve BV, to unload the com pressor and its motor, .this valve then being closed wholly or partly to obtain the maximum e?iciency within the system by the‘ desired type of operation ‘of the refrigeration control del vice RC. 7 ’ ' By adjustment of the liquid control device LC, the temperature of the liquid within the well 53 may be set at any desired point, or successively at a plurality of points at which direct com—' parisons of the readings of the devices SD and TD may bemade. '_ ' ; > When the device is to be employed, for exam If it is now desired to test this same’ device ple, for testing the engine thermometer of an TD at temperatures above room temperature,' airplane in the temperature range of minus 40 then refrigeration switch RS is opened, and the 20 degrees F. to plus 500 degrees E, the standard “dumping” switch DS is closed. The, refrigera or comparison thermometer SD is inserted into one of the guard sleeves 69, and the device TD ' tion system now comes to a'standstill. The switch‘ DS supplies current to the dumping valve DV under control of ‘the dumping control device to be tested is inserted into the other. Assuming that the test is ?rst to be made at so that the valve DV opens and liquid ?ows low temperatures, the main switch MS is closed, 25 DC, from the chambers 55 through the discharge pipe along with the refrigeration switch RS. As point 35, at valve DV, and back into the receiver R. ed out with respect to the circuit diagram of Fig It will be noted that the compressor is no longer ure 6, current now ?ows to energize the com pressor and fan motor CM, FM and a refrigerat ing system operates to produce and deliver a liquid refrigerant under pressure into the re ceiver R. When the compressor has ‘operated until the pressure within the manifold 43 (Fig ure 5) has fallen to a desired low point, the re frigeration control RC operates and the compres sor and fan are stopped again. It will be noted that this action can occur, if the valve EV is operating, so that theevaporation of refrigerant liquid in the chambers 55 soon builds up the pres sure within the return conduits 26, 21 and. asso ciated parts and the pressure in manifold 43 rises until the dumping control device DC closes to actuate the valve DV as aforesaid, and, fur ther, this pressure is being exerted upon the liquid refrigerant in the chambers 55, to expel this refrigerant downwardly into the receiver R. - The check valve 31 prevents any blowing of-gas closed, without any refrigerating effect being re or liquid‘ from the receiver R backwardly into vealed within the testing receptacle housing RH. the chambers‘ 55 at times when dumping is not " When the switch LS is closed, however, further being accomplished, thus serving in series with circuits are set up and the pilot lamp WP is lit. the valve DV for accomplishing this purpose and? These further circuits include a sensitive regu safeguarding against possible leakages through‘ lation at the liquid control LC, for determining the valve DV. the current which energizes the winding I06 of When the chambers 55 have been emptied; the the solenoid valve EV. When the over?ow con 45 temperature of the liquid rises slowly, andthis trol device 0C is warm, the bulb 220 causes the behavior can be observed on the devices SD, "ID. liquid control device L0 to close its contact and This effect can be accelerated by energizing the thereby cause opening of the valve EV. Liquid heating switch‘HS,'so that current flows through from the receiver R then flows through the de—’ one'or more sections of the heating elements HE, hydrator DH and conduit 23, passing through HF as described above. If liquid is still contained the heat interchanger, and through the valve EV within the chambers 55,'evaporation occurs rap into the chambers 55 of the evaporator or boiler idly, until the aforesaid pressurefsystem is set EB, and continues to rise therein until a portion up until the dump valve DV is opened and this over?ows through the conduit 30 and passes‘into liquid discharged. The continued heating is un the over?ow control device OC. As explained 55 der control of the heat control device HC, which, a above, this causes a cooling of the control bulb at the presently-set temperature, opens the‘cir 220 so that the liquid control device LC effects cuit path through the heating switch ‘and the closing of valve EV. It will be understood that elements HE, HF. By adjustment of the heat normally ?ash gas is formed as the preliminarily control device HC, the liquid in the well 53 may cooled liquid passes the valve EV and drops to 60 be brought to and maintained at a desired tem the low pressure prevailing in the evaporator EB, perature, or shifted in ‘succession to various thereby assisting in the rapid movement of ?uid steps of temperature for comparison of the de through the supply conduit 25 and also to pro vices SD, TD. ' ‘ duce agitation within the chambers 55. The During this heating cycle, the white pilot lamp > liquid refrigerant itself is cooled to a low tem WP is always extinguished, and the red heating perature, and absorbs heat from the walls of the pilot lamp RP is lit. _ I 7 7 chambers 55. These gases pass upwardly in the Having completed the inspection and compari chambers and move through the return conduit son of the device TD, it may be removed. If the 26 and liquid trap LT, and thence through the heat interchanger X and conduit 21 back to the 70 testing of ‘the next device is to be accomplished from the low temperature end of the range, then compressor ‘again, and also causing a rise in the the heating switch HS is turned to the “off” po pressure prevailing in the manifold 43 so that sition. No current now ?ows either to the heat the refrigeration control device RC can be brought ing 'or to the refrigeration system. ' The dumping into operation to maintain a suf?cient‘supply of liquid refrigerant in the receiver-R. ‘ - switch DS is kept open to assure that the dump-- ‘ . lilf ingv valve DV will remaillclosedz. ‘While the- sys tem could be restored to‘ a low temperature by permitting‘ the liquid‘ to: enter the chambers,‘ 5.5, I 12: erant‘ in. the; refrigerating circuit ‘and' its. lower part beingconnectedto deliverthe liquid, refrig erant. to thevalve, the. lowerrend chamber being. this would, represent a. loss of: ef?ciency and-ia. connected'in' the circuit to receive the-returning lack? of economy corresponding to the. WOI‘kflIEI 5 gaseous refrigerant from' the evaporator and the quired for producing the necessary quantity‘ of: refrigerant liquid. Hence, it. is. preferred to. use; an intermediate-cyclefor lowering this tempera; ture quickly/and economically. For this purpose; as described above in connection with. Figure 4,. a liquid such as water is admitted from connec-l tion [-50: through valve l5li', and flows, through the coil 65 contained. within the liquidirr the well 53,, and rapidly brings this liquid. and the. immersed, structures down to:v the: temperature of available water, the water being discharged from’. the outlet I53. When water, for example,;is.em. played; as such a, liquid, it is desirable to elimi nate'this water prior to‘ determinations; at: low higher end chamber beingconnected‘ to deliver the gaseous refrigerantto-the compressor: 4'. In an apparatus for maintaining- a temperature condition in a chamber, a, refrigeration’ sys tem including a: compressor, a condenser, an. eXpansion valve and an evaporator connected in a refrigeration circuit, said evaporator being lo cated in- heat-exchange relationship to said. chamber; a’ heat interchanger connected in- the circuit. and including. a housing having internal; ' walls dividing it into two end compartments: and a center compartment, a tube in the» center com partment. and communicating. with the end com partments, the housing and tubebeing positioned. temperatures; and for; this purposethe valve 1T5“; 20 with one end chamber higherythanthe other, thev is closed. and valves. I54, I55? are? open. * Water upperjpa-r-t of the center chamber being connected now'?ows‘through the drain. connections-L hi3, [5:5 to receive liquid: refrigerant» in the- refrigerating the: system: is clear; Further testing: can. now be ‘accomplished in the; manner: described. above,- ‘ ‘ . . ' It. is- obvious. that the. invention. is not Jliinited ' to. theform of, construction shown; but. may be practiced in many ways within.’ the: scope: ‘of ‘the appended‘: claims. I claim: ‘ circuit and its lower part being connected; to de liver the liquid refrigerantto-the valve, the- lower 25 endv chamber being connected in the circuit toreceive. the- returning; gaseous refrigerant from: the evaporator and the. higher end chamber being connected to‘ deliver the gaseous refrigerant to’ the. compressor ;v an; over?ow conduit connectedzto‘ ‘ > 1.. In'an: apparatus; for maintaining a; temper ature-condition in a. chamber,. a, refrigerating:sys-v tem. including meansfor-liquefying. refrigerarni' gas, an evaporator, said. evaporator being? located in'heat-exchange relationship to- said chamber, conduits for delivering the; liquid refrigerantto; the evaporator and returning refrigerant; gas. to said. evaporator and including a warmed ch'am-r ber, over?owing liquid- beingY effective to' lower“ the-temperature of. said warmed chamber, means, responsive to the temperature of said warmed chamber for determining the operation’ of said valve, and. a liquid» discharge conduit from- said. loWer end compartment tcsaid-warmed chamber. 5.. In an apparatus for maintaining. a temper ature. condition in a. chamber, a refrigeration controlling: said. delivery or theeli‘quid refrigerant. system including a. compressor, a condenser, a an. over?ow‘ conduit, connected; to said; evaporator. 40 valve and. an evaporator connected in agrefriger the" liquefying means and: including *m'cansl for: and including‘ a warmed. chamber, over?owing: liquid being; e?ectivet to- Iowerrthe' temperature of said. warmed chamber, and meansfresponsive: to: tion circuit,,.saidy evaporator being located inheate exchange relationshipato‘said ch'amber, an ex: ternally heated over?ow chamber ‘connected to the temperature of said warmed chamber-fende said‘. evaporator, and to. the refrigerant gas- return termining the operation. of said: controlling 471 tothe compressor, temperature responsive means means; ‘ i > ' ' ' ' ' ' , 2;. Inan: apparatus for maintaining: a, tempera:-v ture condition inz'ar chamber, at refrigerationjsys ‘ tom-including a compressor, azcondensergi a valve located in the-chamber for contactwith and quick 1 chilling by over?owing refrigerant liquid from the evaporator and effective for determining the operation of said valve, and means'respon-siveto. and. an evaporator" connected: hr a- refrigeration. 50 the pressure at.- the inlet to said- compressor. for circuit; saidi'evapgorator being. located inf heat exchange relationship to saidchamber, - an overe' ?ow conduit from’ said evaporator; an. over?ow; control device supplied‘. from- said conduit and determining the operation of said compressor. 6:. In an, apparatus for maintaining a-tempera turecondition in. a. chamber, a, refrigerating sys tem including a compressor, a condenser, a res-y having meansforrwarming the same; over?owing; ' in CA . ceiver, an expansion. valve and an evaporator liquid entering said device being eifectiver to connected in a, refrigeration circuit, said evapoe lower the temperatureof said. device-u and means responsive “to; the temperature; of: said’ device: rator being located in heat-exchange relationship‘ nal; wallsv dividing it into two end compartments and; a-scente-r compartment; a tube ‘in the center compartment.» and. communicating~ with the end tor being located in heat-exchange relationship to. said chamber, said evaporator having a- con. for closing andiopening said? valve. ' du-it extending. from a low. level thereof to. said 3. In an apparatusfformaintaliningratemperm CO receiver and, including, a dump Valve, and means ture: condition in; a chamber; a refrigeration sys controlled. by the pressure at the inlet of. said tenrincludi'ng a. compressor, a: condenser, anzexe compressor. for determining the o'peni-ng'of. said pansion. valve and: an evaporator’ connected in a dump valve; ' refrigeration circuit, said evaporator‘ being lo! 7. In an apparatus for maintaining. a tempera cated; in heat-exchange relationship to' said‘ ture condition in a chamber, a. refrigerating sys chambc?and: a1 heat interchanger connected in? tem including a compressor, a condenser, a, re. the circuit and including a, housinghaving-inter; ceiver, an expansion valve. and; an evaporator compartmentsthe. housing and time being posi tioned at an: angle to-thehorizontal of substan. tially '3‘ degrees ‘with: one end chamber higher, thanthe. other, the. upper partjof the.» center connected in a refrigeration circuit, said evapora; to( said chambensaid evaporator having a. con_--_ duit extending from a low level thereofv to said. receiver and including a dump valve, and :means, controlled by, therpressure- at the inlet of said compressor for determining- the opening of'said: chamber being, connected to- receive - liquid refrig- 1 75 dump valve, the; liquid-iv supply‘ connecti'dnfrom! 2,406,080 113'? 14. W a duct having a portion enclosed within said con operation of said ?rst cooling means, said second cooling system including discharge means for freeing said cooling system of cooling liquid dur duit. 8. In an apparatus for maintaining a tempera ing times when the heating means or the ?rst cooling means are in operation for establishing ture condition in a chamber, a refrigerating sys respectively high or low temperatures, whereby the second cooling system can be made effective said expansion valve to the evaporator including" tem including means for liquefying refrigerant gas, a receiver, and an evaporator, said evapo for provoking a rapid transition from a high to a rator being located in heat-exchange relation ship to said chamber, conduits for delivering the liquid refrigerant from the receiver to the evap orator and returning refrigerant gas to the lique fying means, a conduit connected with said evap orator at a low level thereof and extending to the receiver and including a dump valve, means for heating said chamber, and means effective upon heating of the chamber for effecting the opene ing of the dump valve whereby to return the re low temperature without load on the said refrig frigerant liquid to the receiver preliminary to extensive heating of said chamber. the evaporator, and means for delivering an aque , eration system and whereby the said second cool' ing system places essentially no load upon the heating means and first cooling means when either of the same is in service. ’ 14. In an apparatus for maintaining, a tem perature condition in a chamber, a refrigerating system including an evaporator located within the chamber, means for heating the chamber, a cooling coil within the chamber and surrounding ous liquid through said cooling coil independently 9. In an apparatus for maintaining, a tempera 20 of the operation ‘of the refrigerating system for ture condition in a well chamber, a refrigerating reducing the temperature within the chamber system including means for liquefying refrigerant _ during transition from a heating cycle to a cool gas and an evaporator, said evaporator being lo ing cycle in said chamber, said delivering means cated in said well chamber and comprising a including discharge connections whereby the structure having two separate evaporator spaces, a liquid supply manifold connected to said spaces cooling coil may be emptied of liquid preparatory to operation of either the refrigerating system and to the liquefying means for receiving refrig or the heating means. erant liquid therefrom, a refrigerant gas mani 15. In a testing apparatus for producing suc fold connected to said spaces and to the liquefy cessive hot and cold effects of varying degrees in ing means for returning refrigerant gas thereto, 30 a chamber, a ‘ refrigerating system including an overflow manifold connected to said spaces means for liquefying refrigerant gas, an evapo and to a warmed chamber, and means responsive rator in heat exchange relationship to said cham to the temperature of said warmed chamber for ber, and conduits including control means for the determining the delivery of refrigerant liquid into 35 circulation of liquid refrigerant from the lique said liquid supply manifold. fying means to the evaporator and of refrigerant 10. A thermostatically controlled calibrating gas from the refrigerator to the liquefying means; apparatus for subjecting devices to testing tem a heater in heat exchange relationship to the perature at varying points within a range above chamber; means for quickly removing liquid re and below 32 degrees Fahrenheit, comprising a frigerant from said evaporator preliminary to a 40 refrigerating system including a receiver for liq test requiring an increasing temperature, and ue?ed refrigerant and an evaporator, said evapo means for passing cooling water in heat exchange rator including means for receiving. the device to relationship to the chamber during a test requir be tested, a heating system for said evaporator, ing a decreasing temperature, said water-passing means for controlling the heating and cooling means including devices for removing the Water systems, and a discharge leading from said evapo when the temperature during the test is below the rator to said receiver and including a pressure freezing point. responsive valve means for opening said discharge 16. In an apparatus for maintaining a tem when the pressure in the evaporator exceeds the perature condition in a chamber, a refrigeration pressure in said receiver. system including a compressor, a condenser, a . "11. A temperature-controlling apparatus com valve and an evaporator connected in a refrig prising a heat-insulating casing having a liquid eration circuit, said evaporator being located in receiving well, inner and outer walls and closing walls for providing an annular chamber within said well, the space within the chamber being open at its upper and lower ends, means for sup plying refrigerant liquid into said chamber and heat-exchange relationship to said chamber, an over?ow conduit from said evaporator, an over 55 flow control device supplied from said conduit and having means for warming the same, a conduit by which liquid is quickly drained from said over for withdrawing refrigerant gas therefrom, means flow control device, the liquid over?owing into for heating the contents of said well, and means said device being effective to lower the tempera for energizing said heating means. ture of said device, and means responsive to the 12. A temperature-controlling device for com 60 temperature of said device for closing and opening paring instruments, comprising a casing, struc said valve, said responsive means including a tures each including inner and outerwalls and thermostatic device having a bulb located in said closing walls for providing an annular chamber over?ow control device for contact by the over within said casing, manifold conduits each com ?owing liquid for effecting a quick'valve closing municating with the chamber of each structure movement when liquid enters the device and at the same predetermined level thereof and me whereby the quick drainage of liquid from and chanically connecting said structures, and a heat warming of said device assures a quick valve open exchange coil extending around said structures. _ ing movement when the over?ow ceases. 13. In an apparatus for producing in a cham 17. In an apparatus for maintaining a tem ber rapid transitions between selected tempera 70 perature condition in a well chamber, a refrig tures, means for heating said chamber, a ?rst erating system including means for liquefying re means for cooling said chamber and including a frigerant gas and an evaporator located in said . refrigeration system, and a second cooling sys well chamber, said evaporator comprising two tem for delivering a cooling liquid for heat ex spaced outer walls located at essentially the same 75 change with said chamber independently of the 2,4;(165080 1'55 ‘ level, two inner walla~ located within a-nd'sealed to; the outer Walls to. provide two; annular evapo rator; spaces with a compartment inside each in men wall,‘ andv constantly open manifold; connec tions‘ to: said; spaces for ‘delivering refrigerant liq uid‘ thereto and returning refrigerant gas there from and also; for establishing, a connection by which’ a maximum liquid level is established‘ by the‘?ow'of liquid refrigerant, from the receiver to the-evaporator, a liquid'over?ow conduit lead~ ing from the evaporator at a high level thereof; means for controlling said valve and including a heat-responsive‘ element ‘ positioned to respond‘, to‘ the'temperature of a part of said over?ow con duit,_ and heat-exchange means connected- to said; conduit at said part for maintaining said ele over?ow'from the spaces, the compartments with in the evaporator Walls being open» at the- tops and 10 ment normally at a temperature above that of the liquid in the evaporator, whereby liquid over-' bottoms‘ for receiving instruments to lee-subjected ?owing from the evaporator is- effective at said to the temperature in the well chamber- and for part of the over?ow conduit to chill said heat permitting free circulation of ?uid in the Well responsive element immediately upon. contact into and from said compartments. therewith and cause said element, to procure an 18; An apparatus having a refrigerating. system’ abrupt valve-closing movement of the/controlling 7 including a receiver for lique?ed refrigerant, an 15 means. ' evaporator; conduitmeans including a valve for JAMES MADISON LAIRD.