US1636350A - Portable psychrometer - Google Patents

Description

`Fuly 19, 1927.

J. ARMSTRONG PORTABLE PSYCHRQMETER Filed Aug. 51 '1926 2 SheetsSheet L. U0 KUL Jul 19 1927.

y J. ARMSTRONG PORTABLE PSYCHROMETER Filed Aug. 1,51 1926 2 Sheets-Sheet 2 IN VEN TOR l ll lul 0 ff/vi( Patented July. 19,. 1927.

UNITED STATES 1,636,350 PATENT-'b' OFFICE.

JOSEPH ARMSTRONG, l' ALLSTON, MASSACHUSETTS, ASSGNOB T0 AMERICAN MOTS- TENING COMPANY, 0F BOSTON, MASSACHUSETTS, A CORPORATION 0F MAINE.

PORTABLE PSYCHBOMETER.

Application led August 31, 1928. Serial No. 132,688.

This invention relates to improvements 1 n portable psychrometers. More especially. 1t relates to instruments of this sort 1n wh1ch a fan is employed to drive a blast of air past I the thermometer bulbs and has to do particularly with the provision of manually actuated mechanism for rotating the tan.

In the working of fibrous materralstsuch as cotton and wool for example, it 1s hlghly 1'0 important that the air coming 1n contact with these materials be tempered with the proper amount of entrained moisture. Hu-

midifying apparatus is avallable for supplying this moisture and control devlces have been developed for regulating their moisture discharge in accordance with the air conditions existing at the location of the control units. The latter, however, are usually mounted in some central or average l0 location in a room where there 1s a convenient support and it is not unusual to find that the air conditions there are not the same as those of the region closely ad]acent to the material being worked. It is accordingly desirable to test the air condltlons at various locations more or less remote from the lcontrol devices and in greater proximity to the material itself. The present invention is directed to the provision of a psychrometer which can be carried in hand to any location, and there held stationary while a continuous blastv of the air being tested 1s driven past the wet anddry bulbs of its thermometers.

provide a simple compact device in which there is a fan for moving the air past the bulbs and mechanism by which the power of the testers thumb or finger is utilized to o effect rotation of the fan. It is a feature of the device that when the wet and dry bulb temperatures have been determined the percentagesof relative humidity and cotton or vwool regain, corresponding to those temperatures, can be readily ascertained from an integrating device mounted on the instrument. v

These objects are attained byv mounting a pair of thermometers at the front of a vertically extending casing which rises from a hollow base that serves as a reservoir for water. The latter is carried to the bulb of one of the thermometers by a wicking encasing the bulb. A rotatable fan is set within the casing in position to blow apsample of air vWhen thus set, the percentages of cotton It is an object of the present invention tol uniformly past both the wet and dry bulbs. The casing has an external handle at the rear by which the instrument can be su ported in one hand, and close by the han e is a rod which can be pushed downward by the thumb or a finger of that hand. This rod is part of power transmission mechanism whereby the linear motion imparted to the rod is transformed into rotary motion of the fan. A ratchet mechanism permits a spring to return the rod to starting position ready for another push downward by the operator while the momentum ofthe fan continues it in motion. Thus a sample of air is caused to blow uniformly past both thermometer bulbs, gradually lowering the temperature of the wet bulb thermometer in accordance with the amount of moisture the passing air is able to take up from .the wicking.

- On the front of the casing, between the thermometers, is an integrating device having a movable element which can be Set in accordance with the wet and dry bulb temperature readings of the thermometers.

regain, relative humidity and wool regain corresponding to the said temperatures will be indicated simultaneously by the device.

It is intended that the patent shall cover by suitable expression in the appended claims whatever features of patentable novelty exist in the invention disclosed.

In t e accompanying drawings:

y Figure 1 is a front elevation of aportable psychrometer embodying the present invention;

Figure 2 is a side elevation, in medial section on line 2--2 of Figure 1;

Figure 3 is a plan, on line 3 3 of Figure 2, but with most of the base cut away;

Figure 4 is an elevation on line 4:-4 of Figure 2, of the lower end of the push rod and connected gearing;

Figure 5 is an elevation like Fi re 4, but on line 5-5 of Figure 2, showing the mechanism as seen from the front; and

Figure 6 is a rear view of the instrument.

Referring to the drawings, a casing 10 has a hollow base 12 holding a supply of 105 Water which may be poured into it through an opening normally closed by screw cap 16. Two thermometers 18 and 20, one for registering the dry bulb temperature and the other for registering wet bulb tempera- 110 ture, are mounted in ves formed by side strips and 10" astened to the front edges of the side walls 10. The bulb of each thermometer extends below its supportin strip to near the bottom of the cas in be 'nd a rforated cover plate 22. The bu b of tiig wet thermometer is encased within a wick 26 which extends into the reservoir base 12 and by capillary action feeds moisture to the region of the bulb where it is evaporated by the air around it. This air in the immediate vicinity of the wet bulb soon becomes more or less saturated and cannot then absorb moisture as fast as would the air further removed from the bulb; in fact the entire air within the casing becomes slightly moistened and as a result the dry bulb thermometer actually reads lower than the tem erature of the air outside the casin and t e wet bulb thermometer reading is higher than that showing true wet bulb depression. In order to insure accurate readin of the two thermometers there is rovided a fan 28 set to draw outside air t rough an opening 29 in the back of the casing, and blow it uniformly across both bulbs and out through the perforations 24 in the front cover plate. Thus a continuous stream of the air to be tested affects both thermometers, causing the dry bulb instrument to show the actual temperatures of the airand the other thermometer to show the ltemperature corresponding to the wet bulb depression for that air. The latter is of course dependent upon the actual humidity in the air and the amount of moisture that can be absorbed from the wick.

A handle 30 is provided on the back of the casing by which the pychrometer can be held in the hand at any esired location. The upper end 30 of'this handle ro'ects through an upper openin 32 in t e. ack wall and forms a bearing or a rod 34 which has a button 34 on its upper end in position to be pressed conveniently by the operators thumb or finger. The lower end of this rod is forked and straddles a raised stri which is pressed outward from a di 38 and serves to guide the rod in its linear travel. The disk is mounted on a depending plate 40 attached to the casing by the same means 42 that clam s the lower end of the handle thereto, and is thus positioned centrally of the opening 29.

On the raised guide strip 36 is secured a small plate 46 which overlies the forked prongs 34" of the push rod and keeps the latter from moving away from the ,face of the disk. A spring 48 anchored to this plate and attached to one of the prongs serves to pull the rod upward when the pressure of the thumb is released at the end of a down stroke. The outside e' of one of the prongs 34" is provided with teeth and thus constitutes a rack which meshes with a small pinion 50 supported on a shaft 52 having one bearing in the disk 38 and the other iii a bracket 54 mounted on one edge of the disk with its arm 54 extendin across it. On this shaft 52, and secured the small pinion 50, is a ratchet wheel 54 whose teeth are cut with a driving face on one side and a cam face on the other. A larger gear 56 is also journaled on the shaft 52 beside the wheel 54 and carries on its side a pivoted pawl 58 which is ii1 the lane of the ratchet wheel. When the latter is rotated in one direction by downward thrust of the ush rod, the driving face of one of its ratc et teeth engages the pawl and causes the large gear to turn with it, and since the latter meshes with a small gear 60, fast on the fan shaft 62, the fan is also rotated. When .the rod 34 is moved upward by the sprin 48, the cam faces of the ratchet wheel teet slide freely by the pawl, allowing the fan to continue to rotate under its momentum. Before it comes to rest another downward stroke of the push rod occurs and thus the fan is kept continuously in rotation by the operator succeively pushing the ro'd downward as it is returned by the spring.

The psychrometer can be carried to any location where a test is desired, and by simply pushing down on the rod, as explained, a continuous stream of air can be passed simultaneousl over both the wet and dry bulbs. At first their readings will chan e, the dry temperature slightl rising and t e wet tem erature falling. en the mercu in oth thermometers stands still the rea ing of each is taken and, by means of an integrating device mounted on the instrument, the percentages of relative humidit and cotton 4or wool regain can be quickly determined. y This device comprises a scale plate 64 arranged on the front of the casing between the grooved strips 10 and 10". This late has turned over edges which lie behind) the inner edges of the grooved strips and form ides for a slidin element 66. A slot 64 1s cut centrally of t e scale plate and on one of its edges is laid out raduations 682 from 50 to 110 for examp e, corresponding to the graduations of the wet bulb thermometer. On the slidin element 66, ad'acent the graduations 68 and visible through the slot 64l are similar graduations 70 laid out to represent the degrees of the dry bulb thermometer. On the other edge of the slot 64 are three sets of graduations, one` 72 representing percentages of cotton regain, another 74 representing percentages of relative humidity, and the third 76 representing Vpercentages of wool regain. In proper relation to these three sets of graduations on the xed scale plate are three arrows or indicators 78 on the sliding element.

y los 1,ese,aso

When the readings of the thermometersulb temperature is set opposite the graduation of the fixed wetbulb scale which corresponds to the wet bulb temperature. The percentages of cotton regain, of relative humidity and of wool regain, corresponding to the temperature readings, are then indicated simultaneously b the three` arrows 78 on the respective sca es 72, 74 an'd 76. I

lThe convenience of the psychrometer is obvious. It can be used anywhere that a hand can hold it. It is not dependent upon a source of ower other than the operators muscular e orts. And because it employs no other power mea-ns, as for example an electric motor, thereis no danger of the lead wires becomin entangled in the fibrous material and no re hazard from the sparks of such a motor. The'device is sim e, can be manufactured at small cost, and 1s accurate in operation.` It determines the dry and wet bulb temperatures and enables the tester to 'ascertain from these the 'desired characteristics of the air being tested.

I claim as my invention:

1. A psychrometer comprising, in combination, a casing havin a reservoir for water in its base; a pair of t ermometers mounted on the front Wall of said casing; a wick extending from said reservoir aroundvone of the thermometer bulbs; a fan arrangedin said casing for blowing air to be tested past both bulbs; a handle on the back of said casing -whereby the psychnometer can.l be

held in the hand; a ush rod arranged with respect to said handle to enable the rod to be actuated by the hand holding the psychrometer; and power transmitting connections between Isaid rod `and the `fan for `transforming the linear movement of said rod into rotative movement of the fan.

v2. A psychrometer comprising, in'combination, a casinoP having a pair ofI thermometers mounted th moisture to the bulb of one thermometer lto be evaporated therefrom; a fan arranged within said casing for blowing air to be tested past the thermometer bulbs; means for holding said casing in the hand;v a'nd power ereon; means for supplying transmission means having operative connection with the fan and adapted to receive powerA impulses from the hand and transmit them to the fan, comprising a rod adapted to be engaged by the hand and having teeth along its edge, a train of gearing meshing with the teeth on said rod and adapted to cause rotation of said fan.

3. A psychrometer comprisin in combination, a casing having a pairo thermometers mounted thereon; means for affecting said' thermometers whereby they will show respectively wet and dry bulb temperatures; and means on said casing interposed between said thermometers comprising a scale plate having graduations corresponding to the graduations on one of said thermometers and othergraduations laid out in relation thereto corresponding to percentages of the c1` acteristic property of the air to be determined; another scale movable with respect to said scale plate having graduations thereon arranged in accordance with the graduations of the other of said thermometers and having an indicator arranged to indicate on the percentagey raduations the characteristic property of t e air when said thermometerscales are positioned with their graduations corresponding to their respective thermometer readings opposite to one another.

-4. In apparatus for registering wet and dry bulb temperatures, the combination with the thermometers thereof of integrating means consisting of four stationary scales with graduations corresponding to wet bulb temperatures, cotton regain, relative humidity, and Wool regain percentages respectively, and a sliding scale with indications corresponding to dry bulb temperatures and adapted to be moved relative to the stationa scales; there being three ointers on said slidable scale adapted to in lcate conditions of the air on said percentage scales when the graduation on the slidin scale cor- `responding to the existing dry bul temperature is made to register with the graduation on the Wet bulb'stationary scale corresponding to the existing wet bulb temperature.

Signed at Boston, Massachusetts, this 25 day of August, 1926. JOSEPH ARMSTRONG.-

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