US2392405A - Hair drying process - Google Patents

Description

Jan. 8, 1946. c. A. PHIPPS 2,392,405

HAIR DRYING PROCESS Filed Dec. 16, 1941 2 Sheets-Sheet 1 INVENTOR Jan. 8, 1946. c, p -npps 2,392,405

' HAIR DRYING PROCESS Filed Dec. 16, 1941 2 Sheets-Sheet 2 INVENT OR Patented Jan. 8, 1946 UNITED STATES PATENT OFFICE HAIRDRYING PROCESS I Charles Albert Phipps, HartsdalaN. Y. Application December 16, 1941, Serial No. 423,138' 140m (o1.a4j3') I This invention relates. to an improvedprocess. for drying hair on the human head. It relates more specifically tothe drying of womens hair in a manner which will eliminate the discomfort of present methods.

One of the objects of this invention is toprovide a process for drying womens hair in a greatly reduced time.

Another object of this invention is to provide aprocess for drying womens hair in a cycle which can at all times: be adjusted to the maximum comfort of the subject, and which is. not

limited to the degree of comfort obtainable by the temperature and humidity limitations of the priormethods.

Another object of thisinvention is toprovide a process for drying womens hair in.:which the most favorable conditions for drying the hair with speed and comfort are maintained independently of atmospheric conditions.

A further object of this invention is toprovide a process for drying womens hair by the use .of air-of reduced moisture content, without danger of introducing chemical agents into the hair.

This invention provides a process for'drying womens hair quickly while permitting the sube ject ,to control the comfort of the operation, so that there is no feeling of excessive heat at any time during the process. It also: provides, as part of the same process, a greatly, reduced time of drying, so as to further increase the comfort and convenience of the operation. 1

This invention also provides a process in which air ofa higher temperature than isnow generally used can be employed without discomfortto the subject; and in which air of lower temperature than is now generally used can be obtained by a simple adjustment, while maintaining under both conditions a higher rate of evaporation than is ordinarily obtainable under conditions giving a comparable amountof comfort.

i The hair dryers in general use are of several basic types. In the most common type, airis heated by any convenient means and is blown on the hair with considerable force, after which the said air is allowed to escape. This type of dryer has the disadvantage that it relies wholly upon the increased temperature and .velocity of the air to obtain its drying efiect. The amount of moisture present in the atmospheric air may, at times, approach the saturation point at room temperature under very humid conditions, and the drying properties of this air when heated are accordinglyseverely limited under. the very conditions which produce maximum; discomfort to the subject. Thetime of drying is thus unduly prolonged under these conditions, adding to thediscomfort. r

Another type of. dryer in general use recirculates the. major part of the: air so that it is used again and again, thus avoiding the continuous heating ofnew atmospheric air. Although. this reduces somewhat the cost: of operation, it still further reduces the drying properties of the air in aprogressive manner, as moisture is evaporated :from the hair and recirculated with the air. Although the cumulative efiect of adding. mois tureto the recirculatedairis partially offset. in some dryers .by-bringing in, additional atmospheric air-to replacea part of the moistureladen-recirculated air,,the over-all effect in' dryers of this type is to increase the drying time and decrease the comforter the subjectcby blowing increasingly moisture-laden air onto the hair during allor alarge part of the drying, process. This type of'dryer is also subject-tothe discomfort and increased drying time caused by-humid atmospheric conditions. i

An attempt has been made to correct these conditions by chemically dehydrating the air prior to blowing it'ontothe head of the subject. Several serious objections make this type of dryer commercially impracticable, and in so far as the applicant has been able to determine, it isnot found in use. These objections arethat'it'is not practical to' absorb moisture chemically without incurring-the danger of minute particles of chemical being deposited-inthehairof the subject; that the chemical absorption of moisture liberates heat, making the drying operation uncomfortable; and that the chemicals become progressively saturated with moisture, so that, in the latterpart of the dryingoperation, the absorption is less effective than in. theearlier stages.- Also, the need forehanging chemicals is a nuisauce, and. the cost of these chemicals is not acceptable to the trade .in. view of their lack of practical benefits; V i

i A more-successful. method of partially compensating for. the above deficiencies ofv the present methods hasbeen to produce higher efiective air velocities in contact with the hair, and to improve the distribution-of'this air, so as to obtain increased. rates of evaporation. However, a much more desirable method would be a process to obviate the above-mentioned -deficienciescat their sources, and which; would-also utilize the improvements of -h-igh-:effective velocities and good distribution to-obtain more rapid and comrortabledrying ofwhair than has hitherto been this new result. 1 V

The process by which this invention is carried out comprehends the continuous use of air from 1 which a large part of the moisture content has been removed by refrigerating and reheating air, with means'for controlling the temperature and humidity of the said air, but is preferably accomplished in an economical manner by apparatus described in my Patent No. 2,314,101, dated March 16, 1943,1and in accordance with the schematic flow diagrams in the present application.

The term moisture content of air as used herein is intended to denote weight of water content per unit of dry air, and is synonymous with the term absolute humidity. r

I recognize the following different stages of the operation of drying wet hair on the human head, particularly after the usual setting" of the hair by an operator: Firstly, an initial stage in which the hair is very. Wet and there is a maximum opportunity'for the evaporation of water from the surface of the hair masses; secondly, an intermediate stage, in which the hair is nearly dry on the surface of the hair masses, but not within the saidmasses or on the scalp; and lastly, a final stage in which most of the hair and most of the scalp area'are substantially dry, but in which thereare a few places deep in the hair masses to which the airhas not'penetrated as rapidly as elsewhere,'and whichrequire additional time for 1 drying, These three stagesobviously blend one into the other, but are here separated for the purpose of clearly describing the process. r r

The process of the present invention can be carried out in two general: ways, each of which is a great improvement over all preceding meth ods for drying women's hair. 7

In thesimplest variation of this process, air of greatly reduced moisture content is provided con tinuously throughout all stages of the drying. process, independently of the moisture content of the atmospheric air or of the amount of moisture removed from thehair, The temperature" of-this airis controlled so that,'in the first stage of drying, a '.comparatively' high temperature is possible. The present invention accomplishes systems are either at the mercy of room conditions, or, in the case of ordinary recirculatory systems, have by this time also picked up a quantity of moisture from the hair, and are less able to cool and dry the head than at the start of their operation. During this stage, the reduced temperature of my process is preferably still higher than could be used with a comparable amount of comfort in the systemsusing moistureladen air, and the rate of evaporation is higher because of this higher temperature combined with the use of air of very low moisture content.

As the drying process continues into the third stage, dry areas of the scalp become sensitive to hightemperatures, as there is no moisture remaining to be evaporated except from perspiration, and it is desirable to keep the subject sufficiently cool'that perspiration will be negligible.

Aslthis stage is entered, the very low moisture content of the air is maintained, but the temperature is lowered still further, and may be aping this stage depends almost-wholly upon the continued'use of airof very low moisture content, and it is impossible to produce this condition with any of the .older methods. All methods using I V moisture-laden air are incapable of this result, as

they rely on high temperature for their drying, action. The chemical dehydrators are, by this time, definitely unable to produce their driest air at the very time when the present processdependsalmost entirely upon the use'of air of a very low moisture content. Also, their increased temperature due to heat liberated during absorption of moisture prevents the cooling which is a very important part of the present process.

' The new result of comfortable and rapiddryin'g maintained. :This temperature is under thedirect controlof the subject, and will'be as high a sris consistentwith her comfort. will preferably be no lower than, and may even be higherthan the temperatures used in ordinary hair'dryers with their accompanying discomfort,

Asthe second stage of drying is entered, the

I temperature of the air is lowered slightly by the subject, but the moisture content of the air is' maintained at approximately the same very low level; Such low moisture contentcis of great importance at this stage of the drying operation,

This temperature during this last important stage is thus incapable of being produced by such means. Thenew process is accomplished by, and is the opposite'of, all of the'older processes. I

In the variation described above, my process is particularly applicable to'rnulti-hood dryers using a common air'trea tingunit, which continuously provides air of a reduced moisture content to all of the hoods, the'temperature in each hood being regulated by'supplementary individ ual controls'to' accommodate the varying stages of drying of the several subjects.

In order to accomplish the simplified process above described, it is necessary that a refrigeratbeing used to maintain comfort as theheated air penetrates to the scalp and into the hair masses.

'Less surface moistureis also available to prevent such penetration and to readily produce a,

'coolingeflfect by evaporating. None of the'older methods iscapable of carrying out this impor-I tant part of the present process. [Chemical dehydrators are necessarily less capable of produc- 7 it can] be carried ing and reheating capacity he provided which is capable of maintaining a low moisture content of the air throughout the operation. As the cost of refrigerating equipment rises'very rapidly with an increase of capacity, it is desirable to obtain the practical benefits of this new process with the smallest possible refrigeratingunit. This can be accomplished by modifying the process so that out in a second manner as follows: v 7

During the first stage of drying, there is an abundance of moisture present on the exposed surface of the hair, where it can be easily reached; In this'stage, low moisture content is not of as great importance as it is in the latter stages of the drying operation, as previously set forth; Also," a large volume of air may therefore be used tobetter adVantage than during the intermediate: andifln'al stages of drying. These :conditions permit an economy in thecapaclty of refrigera tion provided by .enablingtherefrigerating systemitoibe designed so as to provide-only an adequate'volume of dry air for the import'ant latter part of the operatiomwith air whichis less dry .being ,permitted in the earlier part oi the operation. This permits recirculatingpart of -the air withdrawn from .the vicinityofthe head or using-a portion of atmospheric air without passing it through-therefrigerating system. :In'this way a mixture of dried and undried air may be supplied to the head duringlcthetime when low moisture content is not critical, and a large-volumeiof partially .dry air is thus m'ade available. Inreffect, when a recirculatory system is used such ia mixture of dried and undried airzissubstantially ofalow moisture content,:as 'a great part of thexrecirculated .air withdrawn from thel'head doe'snot carry .with it a very large'amount of moisture. .In a closedsystem, it is desirable to reach a balance at 'a favorably lowfmoisture content in which the :rate of removalof moisture from the system is at least equal to-the rate of moistureevaporation into the system, to prevent -the accumulating of moisture. Theprocess, in this form, thus consists of supplying .to the-hair during the first stage of drying, air. having a substantially reduced moisture content ascompared with ordinary atmospheric air, at an elevated temperature, which may be as high as is compatible with the comfort of the subjects In the second stage of drying the tem perature of the air is reduced slightly under con- .trol of thesubject, as may be indicated by her sensitivity'toth'e heatpresent, and the moisture content is also reduced inorder to provide im proved drying conditions'and to increase the cooling effect of evaporation,'thus making it unnecessary to effect a substantialreduction intempera- .ture. .In thefinal stage of drying, themoisture content of the air .is lowered to a still smaller amount, and the temperature is lowered further under the control of thesubject, so as to provide comfort for the substantially dry and heat-sensi tivescalp areas, while providing rapid drying of the remaining moisture in thehair. It is of course recognized to'be desirable toprovide for anadequately high velocity of the air over the surface of the hair to be dried to produce efficient drying during all stages of this operation.

Further modifications of the process are described in connection with the flow diagrams.

The diagrams presented herewith are submitted as illustrations of suitable means for accomplishing the processes embodied in this invention. No attempt has been made to show structural form, as apparatus which accomplishes the process described herein may be readily designed by a person well versedin these arts.

Referring to the drawings,

Figure 1 is a diagrammatic illustration in sectional elevation of a device for drying womens hair with air which has been chilled to remove moisture therefrom, having controls to effect the process of the present invention.

Figure 2 is a diagrammatic illustration in sectionalelevation of a modification of the device shown in Figure 1, provided with means for recirculating the air.

Figure 3 is a diagrammatic illustration in sectional elevation of a modification :of the device shown in Figure 2, .provided with means fo by passing atheJrefrigerating :unit i with; apart of ,the

recirculated air, in ordertomore economically put the process-'Ioffthe present inventioninto use.

' Figure 4 7 is a diagrammatic illustrationin sectional=.elevation iof:a modification ofwtheidevice shown'intFigurefi, for serving a plurality of hoods with a central refrigerating and heating system, embodying further modifications in the'control of the process of the present invention.

'It 'is' intendedthat; as the specific control means are-merely. illustrative of the process, the control;;features shown in the various figures may beinterchangedasmay be required to meet the problems of economical design, and that other control devices. notlillustrated maybe used, as .longas they are capable of making the process of thepresentinvention effectual. i

Referring to'Figure 1 in greater detail, air is drawn by apump, fan or the like, such as'the blower i, by means of a tube or duct 46, through a cooling zone 2 which may pass through a tank 3 containingcold heat-conductive fluid such as chilled brine. The air cooling zone 2 may be chilled by any suitable means involving direct or indirect :heat exchange. A preferred-method is touse a refrigeration cycle of any of the conventional types having separate heat absorption and heat dissipation areas. For example only, and for convenience, the single refrigerant compression-evaporation cycle is illustrated inthe drawings, although the invention may also be used with absorption typeand with three-component refrigeration-systems such as the Electrolux cycle, or thelike. For example, a suitable refrigerant may be compressed by compressor I2, condensed in heat dissipating coils I and 42, passed by line [3 through expansion valve l4 into heat absorption coil 15, from which it is passed by line IBback to the compressor.

, The water condensing from theair in zon 2 is removed from'duct 4 by pipe 5 which may be provided with trap 6 to permit automatic operationwithout leakage of air. The chilled air leaving .the .cooling zone is directed by duct 4 over heating surfaces indicated at 1. Heating unit 1 maybe part of the condenser of a refrigerating cycle used to chill the'brinein tank -3, and may be provided with an-adjustable throttle 0r valve 4 to control the flow of refrigerant therethrough. Another part of the condenser of the refrigerating cycle,.indicated at 42,.may be used to dissipate excessiheat from the refrigerating system such .as that-due to the continuous cooling of atmosphericair andthe removal of moisture therefrom, the heat to be dissipated being generally greater than that neededfor reheating the ai by heating unit 1 under most conditions of operation. Throtated into the air passing through duct 4, and in this way adjusting the temperature of the air leaving thecooling and heating apparatus. These valves may be linked toa commoncontrol or handle of'any convenient type, to simultaneously partially open one valve while partially closing the other, so as to permit convenient operation of this control meansby the subject whose hair is being dried.

.A by-pass valve or vane 2 I isprovided topermit a mixture ofatmospheric air with cooled and reheated air at such times as the process is furthered thereby ortheoperation of "the process is made rnoreeconomical, .as would be the .case,rfor example, under conditions of substantially xdry atmospheric air. ,Blow.er I passes the total flow of such air under increased pressure overheating element 8, which may be an auxiliary heater. of any desired type, such as a steam or gas coil or'an electrically heated element'which is, controllable by means of suitable .valves', switches or rheostats 44. Such control means. is preferably arranged to be conveniently operated by thesubject, andmay be linked with a'common control or handle provided for valves 43 and 4|. This linkage may be direct, so that the auxiliary heating element '8 is m'adeeffectivelwhen the handle: is turned to a position forincreasd temperature, or the linkage may be. made through an adjustable thermostatic 7 control 55,. so that'the auxiliary heating element will only be operative when the desired temperature is not produced byheating element 1.

The arrangement illustrated in Figure 1 may be used to make the present process effective. as

follows: Air having a. moisture content substantially below that of atmospheric air may be'corrtinuously produced by passing atmospheric air over the cooling and reheating elements? and I, and withdrawing moisture at 5. This dried air may be mixed with a portion of'undried atmospheric air by the use of bypass 2 i, or may be used without such admixture of atmospheric air,-in

a means of control element 4'4 of heating element 8, and by means of control valves 41 and 43, which reduce the dissipation of heat from heating element 7. of moisture continues, however, so that the moisture content of the air during the latter part of the drying operation may be maintained as low as in theinitial stages, or may be lowered. If vane 2! is used during the early part of the drying operation to bypass atmospheric air around the cooling and reheating elements, it, may be partially or entirely closedduring the, latter stages of drying, to assist in the production of drier air by forcing a greater portion of the air through,

the cooling and reheating operation. I

In Figure 2, air withdrawn from the vicinity of the head through duct H] to blower I is'passed under pressure through cooling zone 2 and over heating elements! and 8 to hood 9, and is distributed with adequate velocity into contact with the hair to be dried. Heating element 8' may be controlled by the subject by means of valve or rheostat 44. In this arrangement, it is assumed that theheat dispersed'into the atmospheric air The adjustment of valves 4| and 43,

The refrigerating of air for the removal *It is also desirable, in providing for'thecomfort of the subject,jto avoid. escape of'warm'air' from the hoodabouther face'and neck. This maybe accomplished by maintaining a slightly sub-atmospheric pressure within thev hood. Such .reduced pressure will-cause a small. flow of :atmospheric airinto the hood, rather than escapeof warmair from the hood, and may be provided in a substantially closed recirculatory system by venting a small quantity of air from the high pressure zone, as by vent H which may be-suit-. ably-placed at or'near the bloweridischargaor at any part of the system'where the pressure is greater than atmospheric.

" The arrangement illustrated in Figure 2 may be used 'tomakethe present process efiectiveas follows: 'Air having a moisture content substanr tially below that of atmospheric air may be produced bypassing air withina recirculatory system'through a cooling zone 2'to chill the air below its dew point, and thereafter over heating units I and 8, withdrawing the condensed moisture at 5. The resulting air of reduced moisture content maybe passed with adequate velocity into contact with the hair to be dried by any suitable means such as hood 9, from which it maybe withdrawn through duct l0 and recirculated by blower K through the system, thus providing a continuous supply of air having a'substantially reduced moisture content throughout the drying operation. In the initial stage of drying, the

temperature of the air supplied to the wet hair is warmed by heating units 1 and 8 to a substantially high temperature which is compatible with the comfort of the subject. As the drying progresses, and the cooling eifect of evaporating liquid in the hair decreases; the temperature of the air supplied to the hair may be reduced under control of the subject by the adjustment of control 44 of heat ing unit 8.

. which may be as low as in the early stages of the from the various warm parts of the apparatus,

suchas the outer surface of hood 9, duct Ill, blower I, and pipe I3 is adequate to prevent an I excess of heat being builtjup' within" the system from the continuous condensation of moisture in cooling zone 2, and from heat added to thesystem ing unit 1, and additional heat is'providd by heating unit 8 under control of the subject whose 'hair is'being dried, as maybe required for the present process.

drying operation, or lower.

In addition to the elements shown in Figure 2, Figure 3 illustrates a duct 20 through which recycled air may by-pass the cooling ' andreheating elements 2 and 1. This duct is provided the quantity of air permitted to pass :therethrough. This by-pass valve preferably willnot be opened until the moisture content of the air within the system is sufiiciently low to'permit v the desired drying action, and it will preferably not be opened thereafter sufiiciently to permit the moisture content of the air to the hood to exceed such amount. This constitutes an effectual means for controlling the humidityof the air supplied to the hood. The use of 'the by-pass is also advantageous in permitting recirculation of air at a high rate with a minimum load on the refrigeration unit. Also, in actual practice, the air leaving the hood 19 will not be saturated with'moisture, and it will be generally sufficient, after an adequately low'level of moisture content has been reached within the system, to pass only sufiicient air through the refrigerator-to re.- move the increment of moisture picked up on each recirculation cycle. However, if desired, vane 2| can be adjusted to further'reduc'e the moisture content during the drying operation, by causing an adequate volume Man to pass 7 through the cooling and reheating zones.

The air treating unit'illustrated in Figure 3is inlet andz-outleta tozandirom .theacooling. chamher; 2.; ,andais: also, designed. so; as" to require a minimum of insulation. These, improvements provide economy of operation and utilize heat transfer, through the; walls of the ducts to further thevdesiredprocess, as is described in greater detail;in.my,-Patent No.- 2,314,101, dated March 16,-,1943. It is-also desirable to provideisuitable means for precipitating any entrained droplets of-water from the air leaving the cooling zone 2. Suitable meansmay provide" a quick change in direction'of theair stream by. baffles 22.

The arrangement illustrated inFigure Smay be used. tdmake the present invention effective in the. samemanner as that illustrated in Figure 2, and, as follows: Air having a moisture content. substantially below that ofv atmospheric air may be continuously produced. by passing air within a recirculatory system through a cooling zone 2, where it is chilled below its dew point, and subsequently passing it' over a heating element 1. Entrained droplets of watermay be thrown out by baflles 22, and the condensed moisture may be. withdrawn by' suitable means 5. The continuous supply of dried air may be mixed'with recirculated air from the vicinity of thehead by drawn to blower I through duct l0. In the initial' stage of'drying, the temperature of the air suppliedto the head may be relatively high while being compatible with the comfort of the subject, due to the cooling'eifect of rapid evaporation of liquid from the hair by relatively dryair. Asthe-drying'progresses, less-water is available for evaporatingin the hair, and the effect of evaporatingliquid decreases. The temperature of the air-supplied to the head may then be reduced'by'the adjustment of control 44, so that the subject remains comfortable. Vane 2| may, forexample, be left in a fixed adjustment throughout the drying operation, and the refrigeration unit operated continuously, with the resuit; that the moisture content of the air suppliedto the-head during the latter part of the drying operation i maintained at a suitably low level, which may be as low as during the initial stage, and'may be even lower due to the reduced rate of evaporation. An optional method of operation, especially valuable when the individual whose hair is being dried is particularly sensitive to'the application of heat to the'substantially' dry scalp, is to reduce the flow of air thrOughduct-"ZO during the' latter part of the drying operation by adjustment ofvane 2 I, thus forcing a greater'portion of the recirculated air through the cooling and reheating apparatus anddecreasing the moisture contentof the air suppliedto. the head. independently of the rate of evaporation of-moisture from the hair. The capacities of the various parts of the system may be so arranged that, even with vane 2| completely shut, an adequate'volume of substantially dry air is provided to'hood 39. to produce. the velocity necessary for rapid drying. Airof very lowmaintaining\ .-a high,rateof. drying: as compared with; all. former. methods.

The further modification illustrated in Figure 4' shows a .use'of-the present improved processin a ,singleair. treating unitserving a plurality of hoods, and-illustrates additional means for controlling the temperature of theair supply.

Itis generally desirable in a large systemsupplying aplurality of hOOdSttO use two. blowers or a double-actingblower, in rder to reducethe pressure drop. and: reduce the load thateach. blower-is required-to carry; For example,'blowers 32. and 33 are showninFig-ureA connected respectivelyto-the.inlet and the-outlet of. the refrigeration :unit. a

The by-pass-2l. from blower 32-, and air-fromthe blower. 33..discharge into the common-air duct" 34, which is used for supplying airtoa plurality .hoods and the return ducts from-.thesethoods-are preferably suppliedwith individual 'controlvalves orvanes 3.5. These vanes are used to regulate be closed when that hood isoutofservice. .The

two. vanes in. the ducts leading. to andfromuthesame hood are preferably connected togetherin.

some suitable manner, so that a balancebetween the air entering and leaving, that hood-will. be effected atany rate offlowr This .balance. desirably will provide for the return of a. slightlygreater amountof air than is, supplied by the duct leading to that hood; thereby maintaining the desiredslightly subeatmosphericpressure in the hood, theexcess air. drawn in being released.- through the. vent I l. Provision. will, of. course, be made to carefor the increased volume. of the returning air due to its. decreased pressure. The vanes 35 will be adjusted. tomaintain. this-condition in all hoods in .use. The hoods will .be used in such a manner that the. header. hairof the subject will not unduly obstruct either the air supply or air withdrawal passages.

The heat balancaparticularlyin the-multiple unit system, may also require additional. control features in order to permit optimum conditions of operation. For example, the temperature of air to the common supply duct 34 may suitably be the lowesttemperature considered comfortable by any subject. Additional heat may be supplied by heating element 8 to provide the required temperature in any individual hood, according to the present improved process. This, extra heat thus supplied to the system must, of course, b removed by some suitable means. The heat transferred to the chilled air from the heat dissipating coil (is limited as described above and thus. will generally be less than the heat removed by the refrigeration coil I 5 in the brine tank 3, which removes the extra heat supplied by the supplemental heating elementsand by the condensae tion of moisture. This extra heat that must lbe dissipated by the refrigeration cycle may. be re-- leased to the atmosphere by anadditional coil 36' before the refrigerant reachesfthe expansion valve 14'. Coil 36 will generally be of sufficiently large capacity to take, care, of any fluctuations that may occur in the operation of the coil, 1, whether due to heat from supplemental heating elements, or an accumulation ofheatwithinthe. cycle from any other source. I

Additional control. features .providing for. increased flexibility of. operation and effectively controlling the temperature and humidity are the. toy-pass 3T, operated. by valve or .vane 38,, and.

vane. In the event that thetemperature rises to a higher point than desired inisupply duct 34,

this maybe lowered by opening valve 38, thus passing cool air through the by-pass-3'I. This causesadditional heat to be carried by the refrigerantfrom coil 1 to coil .36, and serves asa means of removing heat from the system.; The opposite eifect may be gained and the air temperature raised in duct BA by opening the by-j pass 39' and passingadditional air over the heating coil 1. This withdrawsadditional heat from coil I, preventing its dissipation from the system at coil 36. As it is generally desirable to maintain a constant temperature'in the com mon air supply duct 34. v alyes 38 and 39 may be operated automatically by a suitable thermostat '45 in duct 34. Additional heat may be re.-

quired as, for example, in case of a sudden increase in load. or t the start of operation of the system. Supplemental heating element 40 is shown for this purposeand mav also be under the control of thermostat 45. A filter isindicated at 23, for the purpose ofcleaning the air.

The arran ement illustrated in Fi ure 4 may be. used to make the presentinventionefiective. as follows; A continuous'supply of air of a moisture content substantially reduced below that of ordinary atmos heric air is rovided to common supplyduct 34 by thecooling and reheat ing of air at 2 and 'l. res'oectivelv, with the removal of condensed moisture at 5.. This-air may be. mixed with recirculatedairfrom blower 32 throu h partially open vane zl as the airreturned from the hoods will ordinarily be of-substantially reduced moisture ,content com ared with atmosohericair, and a portion'of such air may be reused. The system will preferably .be

operated so that a balance is'maintained between the overall rate of evaporation, of moisture intothe' system, and the rate of removal of moisture therefrom, at a satisfactorily low moisture contentoftheair;

'Ineachindividual hood. tlie air will be sup,

plied-with. adequate velocity to aid in rapid drying throughout theoneration.- Initially,the substantially dry air will be supplied at a relatively high temperature which is compatible with the] comfort of the subject, adequate heat being ob-"i tainedfrom supplemental heating element 8. As

the drying-progresses, there isless moisture avail:

able for evaporating from the hair, and consequently the cooling effect of the evaporating moisture decreases. supplied to the particular hood is then reduced by adjustment of control M of heating element 8 by the subject. while the moisture content of the air is maintained at least as low as during the early part of the drying operation. In the last sta e of the drying operation, control 44 may finally be adjusted 13113431110 additional heat'is suppliedby heating element 8,-thus providing cool, substantially dry air for maximum comfort of the subject under conditions in'which the'scalp is particularly heat-sensitive, whilemaintaining adequate. velocity of air and a comparatively rapid rate of remo'val'of the remaining'moisture fromthe hair. r'

It should be recognized that the foregoing description of my invention describes methods for drying the hair with maximum comfort in -the shortest practicable time. 'However it is to'be recognized that substantial benefit, in reduced drying time or increased, comfort" to the subject" can be secured by the use of lesseflicient refrig- The temperature of the 'air' eratio'n or less stringentcontrol of absolute nu to remove moisture therefrom and to thereby lower the absolute humidity or the air, subse-: quently reheating the cooledair by passingit over a heating means, and circulating the reheated air in contact with the hair on the head to dry the hair; then as the drying of the hair progresses and the cooling effect of evaporating liquid from the hair decreases, reducing the temperature of the heating means to reduce thetemperature of the air used fordrying the hair, and

controlling the cooling means to maintain the absolute humidity of the air used for drying the hair at least as low as that of the air used in the first part ofthe hair drying process.

2. In a process fo'rdrying hair wet with liquid on the humanhead by means of air circulated in a cycle including the hair and cooling and heating means for controlling the absolute humidity. and temperature of the air passinginto contact with the head, a method of operation for quickly drying the head of a'person with comfort comprising initially passing the drying air over the cooling means to remove moisture therefrom, and to thereby lower the absolute humidity of the air, then reheating the cooled air by passing it over the heating means, and circulating the reheated air into contact with the hair at a temperature compatible with the person's comfort to dry the hair; then as the drying progresses and the cooling efiect of evaporating liquid decreases, reducing the temperature of the heating means, thus reducing the temperature of the drying air to maintain comfort, while continuously recirculating air in the cycle over the cooling and heating means to remove additional moisture therefrom. I

3. A process for quickly drying hair wet with liquid on a persons head by means of an air supply of controlled temperature and absolute humidity/With comfort to the person, comprising initially circulating room air over a cooling contact with the head to dry the hair; then as supply of .controlledtemperature and absolute.

the drying of the hair progresses and the cooling cooling and heating means to remove moisture and controlling the admixture of uncooled room air with the said reheated 'airto maintain a suitable rate of drying.

4. A process for quickly drying hair wet, with liquid. on a person's head by means of an' air humidity, with comfort to the person, comprising initially circulating at least. a portion of said air supply over a refrigerating means to remove moisture therefrom and to thereby lower the absolute humidity of the air, subsequently reheat ing the air by passing it over a heating means and circulating the air in contact withithe' hair at atemperature --compatible' with the persons comfort, to dry the hair; then as the drying progresses and the cooling effect of evaporating liquid from the hair decreaseareducing the ternperature of the heating meanstoreduce the temperature of the air in contact with the hair, to maintain comfort, while continuously passing at least a portion of the air supplyover the refrigerating and heating means'to maintain a lowered absolute humidity of the said air circulated in contact with the hair.

5. A process-for drying hair wet with liquid on the human head by-means of air circulated in a-cycle including the hair and refrigerating and heating means for controlling the temperature and absolute humidity ofthe air passing into contact with the head, comprising initially circulating air within the cycle over the refrigerating means to remove moisture therefrom and to thereby lower the absolute humidity of the air, subsequently reheating the air by passing it over the heating means, and circulating the reheated air in contact with the hair on the head to dry the hair; withdrawing moisture-laden air from contact with the hair and recirculating said moisture-laden-air over the refrigerating and heating means and returning it again into contact with the hair; and as the dryingprogresses and the cooling effect of evaporating liquid decreases, reducing the temperature of the heating means, thereby reducing the temperature to which the air is heated, thus maintaining comfort, while controlling the refrigerating means to maintain a lowered absolute humidity of the said air circulated in contact with the hair.

6. A process for drying hair wet with liquid on the human head quickly and with comfort by means of air circulated in a cycle including the hair and refrigerating and heating means for controlling the temperature and absolute humidity of the air passing into contact with the head, comprising initially circulating air within the cycle over the refrigerating means to remove moisture therefrom and to thereby reduce the absolute humidity-of the air, subsequently reheating the cooled air by passing it over the heating means, and circulating the reheated air in contact with the hair on the head to dry the hair; withdrawing the moisture-laden air from contact with the hair and recirculating said moisture-laden air over the refrigerating and heating means and returning it again into contact with the hair; and as the drying progresses and the cooling effect of evaporating liquid inthe hair decreases-reducing the temperature of the heattionof moisture therefrom by passingthe air over said refrigerating means,v and removing'the condensed moisture; then applying such heat as may be required to said stream by passing the air over said heating means; then mixing the resulting heated air with the uncooled withdrawn air in the other stream, and returning the warm mixture in thecycle into contact with the hair; then as the dryingprogresses and the cooling effectof evaporating liquid from the hair decreases, reducing the temperature of the air passing into contactwith the hair by controlling said heating means, thus maintaining comfort, while maintaining the absolute humidity of the air substantially below that of saturated air at the new temperature by controlling the relative proportions of air in the two streams, to maintain a high rate of drying.

8. A process for drying hair wet with liquid on the human head quickl and with comfort by means of air circulated in a cycle including the hair and refrigerating and heating means for controlling the temperature and absolute humidity ofthe air passing into contact with the head, comprising initially passing into contact with the hainwarm air of a temperature compatible with the persons comfort, and of absolute humidity substantially less than that of saturated air at that temperature; withdrawing the air from contact with the hair; dividing said air into two streams'; cooling one stream to cause condensation of moisture therefrom by passing the air over said refrigerating means, and removing the condensed moisture; then applying such heat as may be required'to said stream by passing the air over said heating means; then mixing the resulting heated air with the uncooled withdrawn air in the other stream, and returning the warm mixture into contact with the hair; then as the drying progresses and the cooling effect of evapcrating liquid from the hair decreases, reducing the temperature of the air passing into contact with the hair by controlling said heating means, thus maintaining comfort, while reducing the absolute humidity of the said air by controlling said refrigerating means and controlling the relative proportions of air in the two streams, to maintain a high rate of drying.

9. A process for drying hair wet with liquid on a persons head, comprising passing air in con- --tact with refrigerating means to condense and ing means, thereby reducing the temperature to which the air passing into contact with the hair is heated, thus maintaining comfort, and also controlling the refrigerating means to further reduce the absolute humidity of the air to maintain a high rate of drying.

'7. A process for drying hair wet with liquid on the human head quickly and with comfort by means of air circulated in a cycle including the tact with the hair; dividing said'a'ir into two streams; cooling one stream to cause condensacombining said icy-passed air and said heated air;

subsequently passing said air over supplementary heating means and theninto contact with the hair, evaporating moisture therefrom; withdrawing said air after contact with the hair and recirculating at least a part of said air in contact with said refrigerating means to remove additional moisture therefrom, and by-passing the remaining part of said air around said refrigerating and heating means, thus controlling the absolute humidity of said air; initially in said drying process providing said air at a temperature compatible with the persons comfort, then as the drying progresses and the cooling effect of evaporating liquid from the hair decreases, reducing the temperature of said air by adjusting the supplementary heating means to maintain comfort, while maintaining a suitably low absolute humidity of said air.

10.;A process for drying hair wet with liquid on the human head bymeans of airpassed in contact with refrigerating and heating means for controlling the temperature'and absolute humidity or the air applied to the head, comprisinginitially. withdrawing air from the room; dividing said air into two streams; cooling one stream by passing the air over said refrigerating'means to cause condensation of moisture therefrom and to 7 thereby lower the absolute humidity; removing the condensed moisture, and, subsequently reheating the cooled air by passing the air over said heating means; mixing the warm dehumidified air with the uncooled air in the other stream, and passing the mixture into contact with the hair at a temperature compatible with'the persons comfort to dry the hair; then as the drying progresses and the cooling effect of evaporating liqstream aslmay be required by passing the air over uid on the hair decreases, reducing the temperature of the heating means, thus reducing the temperature of the air passing into contact with the hair while maintaining a suitably reduced absolute humidity of' said air by controlling the refrigerating means, thus maintaining comfort and a rapid rate of drying.

11.- Aprocess for quickly drying hair wet with liquid on a'persons head by means of an air sup- ,plybf controlled temperature and absolute humidity with comfort to the person, comprising 'initially'circulating at least a portion of said'air supply over cooling'means to condense and remove moisture therefrom, and to thereby reduce the absolute humidity of said air supp y; subsequently circulating said air supply overheating means and then into contact with the hair at a te'mmr-ature compatible with the persons com- .fort at that absolute humidity; then as the drying progresses and the cooling efiect of evaporating liquid on the head decreases, maintaining a lowered absolute humidity of air supply b condensing additional moisture therefrom, while lowering the-temperature of the heating means, thereby lowering'the temperature of the air circulated in contact with the hair below the temperature used in' the first part of the drying op- K eration;

'12; A process for dryinghair wet with liquid on the human head quickly and with comfort by means of 'air circulated in a cycle including the hair and refrigerating and heating means for controlling the temperature and absolute humidity of the air passing into contact with the head, comprising initially passing into contact with the hair, warm air'of a temperature compatible with 'thepersons comfort and of an absolute humidity substantially less than that of saturated air at that temperature; withdrawing the air from contact with the hair; cooling it by passing said air in contact with the refrigerating means to cause condensation of moisture therefrom, and removing the condensedimoisture; then dividing the 'air into two streams; supplying such heat to one said heating means; then mixing; the heated air with the unheated air, inthe, other stream, ;and returning the mixture in the'cycle into contact with the hair; then as the drying progressesand the cooling effectofevaporatingliquidrfrom the hair decreases, reducing the temperature ofthe air passing into contact with the hair by controlling the relative proportions of airin the two streams, thusfmaintaining comfort, while maintaining the absolute humidity of the air substantially below that of saturated air at the new temperature 1 by, controlling the said refrigerating means, thus maintaining a highrate of drying.-

13. A process for drying hair. wetwithliquid on the, human head quicklyand with comfort by means of air circulated in acycleincluding the hair and refrigerating and heating means-for controlling the temperature and absolute humid-'- ity of the air passing into contact with the head,

comprising initially passing into contact with the hair, warm air of a temperature compatible with the persons comfort and of an absolute humidity substantially less than that of saturated air at that temperature; withdrawing the air from contact with the hair;then dividing the air into two streams; cooling one stream to condense moisture therefrom by passing the air over saidrefrigerating means; removing the condensed moisture; then mixing the cooled air with the other stream of uncooled air; then supplying such heat as may be required, by passing the air over said heating means and returning the mixture in the cycleinto contact with the hair; thenas the drying progresses and the cooling effect of evaporating liquid from the hair decreases, reducing the temperature of the air passing into contact with the hair b controlling said heatin quently reheating said air by passing, it overa heating means, mixing uncooled room air with said reheated air, and passing the mixture in contact with thehead to dry the hair; then as the drying of the hair progresses and the cooling,

effect of evaporating liquid from the hair decreases, controlling saidrheating means and the admixture of uncooled-room air with said reheated air to reduce'the temperature of said air used for drying the hairto maintain comfort.

' CHARLES ALBERT PHIPPS.

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