Nov. 3, 1942.

G, M, Boom _

GAS

2,300,642

DRAWING APPARATUS

v

Filed Feb. 2, 19:59

4 Sheets-Sheet; 1

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f

_ INVENTOR

A; ATTORNEY

NW- 3, 1942'

> 4'

G.- M. BOOTH

2,300,642’

GAS DRAWINGQPFARATUS Filed Feb. 2, 1939

' 4 Sheets-Sheet 2

A; ATTORNEY

Nov. 3, 1942.

G. M. BOOTH

2,300,642

GAS DRAWING APPARATUS

Filed Feb. 2, 1939

1

Q

A

4 Shéets-Sheet 3

2%Z‘ZNVENTIOR M W '

A; ATToiQNEY

Nov. 3,1942.

G, M, BOOTH

~ ' '

2,300,642

GAS DRAWING APPARATUS

Filed Feb. 2, 1939

4 SheetST-Sheet 4

‘26/ , 60

‘232mm V

ullvNvENTOR

1,; ATfoRNEY

2,,642

Patented Nov. 3, 1942

»

UNITED STATES PATENT 2,300,642 GAS DRAWING APPARATUS George M. Booth, West?eid, N. J., assignor to Wallace & Tiernan Company,- Inc., Bellevilie, N. 3., a corporation of New York

‘

Application February 2, 1939, Serial No. 254,223 ' ‘

17 Claims.

(01. 210-28)

-This invention relates to apparatus for draw ing gas at a controlled rate into ?owing liquid. The invention comprises an improved Venturi aspirator having means adjustable for varying its pulling capacity, and comprises, also, auto matically acting control means for adjusting the adjustable means of the aspirator to maintain constant under varying conditions a desired nega tive pressure between the suction inlet of the aspirator and a ?ow-controlling ori?ce or other 10

’

mines the partial vacuum, or negative pressure, available for sucking the gas. In some cases the negative head under which the make-up water is supplied to the aspirator is constant and the suc tion transmitted to the control ori?ce is deter- I

mined by an adjustable, restriction between the ori?ce and the aspirator, and in- other cases the ?ow rate of the gas is varied by varying the nega tive head against which the make-up water is supplied to the aspirator. Also, instead of sup ?ow-resisting passage through which the gas is ~ plying make-up water to satisfy" the excess ca pacity oi the aspirator in order to maintain the drawn. An object of the invention is to provide an desired negative pressure at the suction inlet, the pulling capacity of the aspirator has been con aspirator‘ having means for adiustably con trolling its pulling capacity such that as the pull 15 trolled to maintain a desired negative pressure at the suction inlet by regulating the operating ing capacity is varied the ?ow rate of- water pressure oi the water supplied to the aspimtor by through the aspirator will be varied more nearly. in proportion to the variation in pulling ‘capacity means of a valve in the supply line. . Adjusting the pulling capacity of the aspirator than has been possible with the means hereto fore employed for varying the pulling capacity of 20 by regulating the operating pressure oi the wa ter has the advantage over supplying make-up aspirators, and thus to provide an aspirator which will operate with good emcien‘cy through a com water under a negative head to satisfy excess ca pacity of the aspirator that the aspirator maybe paratively wide range of gas ?ow rates or with varying liquid supply pressure. Another object operated by the minimum amount of water re quired to maintain the desired negative pressure is to provide an aspirator whereby when there is a negative pressure on the discharge line from at the suction inlet, thus effecting economy in the the aspirator the suction, or pulling capacity, of ' use of water, and that the solution of gas pro dueed is of greater strength. ~ the aspirator may be reduced. without reducing This .method of controlling the pulling ca-~ the liquid flow rate below a certain minimum. A further object is to provide means for auto 30 pacity of the aspirator is, however, open to two matically controlling the adjustment of the objections. First, since the emcien'cy ofva Ven- ' aspirator so as to control accurately the pulling , turi aspirator decreases greatly as the pressure of the operating ?uid decreases. the eiilciency of the capacity of the aspirator to maintain a desired aspirator is greatly reduced when the ?ow rate of negative pressure in the gas passage leading to the suction inlet of the aspirator under varying - the gas is low, that is, the proportion of water to gas is increased largely as the ?ow rate oi’ the gas rates of gas ?ow, varying pressures in the dis charge line whether superatmospheric or sub is reduced. The other defect of this method of controlling the pulling capacity of the aspirator atmospheric, and varying liquid supply pres is manifested when the discharge line from the The invention has been made especially with 40 aspirator extends considerably downward and the syphon effect in the discharge line tends to'pro the idea of providing an improvedapparatus for duce a suction through the aspirator which at introducing gaseous chlorine at a. controlled rate times may be sui?cient to produce the desired into a minor stream of water to produce a solu negative pressure at the suction inlet without any tionto be used for the treatment of water or water at all passing through the asplrat'or. vIn the sewage or for other purpose. In such apparatus use oi’ an aspirator provided with such means for in which chlorine gas supplied at a constant sub controlling its pulling capacity and discharging . stantially atmospheric pressure is drawn through through such a downwardly extending discharge ' a ?ow-controlling ori?ce by- a water aspira'tbr, it line, when the discharge line becomes completely has been the practice to have the pulling ca ?lled with water the weight of water in the line pacity of ‘the aspirator somewhat greater than‘ sures.

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su?lcient to draw gas at the maximum desired rate through the control ori?ce and to have the excess capacity of the aspirator satis?ed by make up water supplied tothe suction inlet of the aspirato'r under a negative head which deter- 55

creates such a suction in addition to that created by the aspirator as to increase the negative pres sure at the suction inlet below that required, with the result that ‘by the‘ automatic control means the water pressure to the aspirator is reduced to

2

2,300,642

an amount below that required to dissolve-the

tive pressure maintained in the suction passage

by the aspirator.

‘ sucked-in gas. As the proportion of undissolved'

gas increases in the discharge line, the syphon effect is decreased and the negative pressure at the suction inlet decreases below that desired and

In the operation of the automatic control mechanism, any increase in the vacuum or nega

tive pressure at the suction inlet of the aspirator

the water supply pressure-is thereby increased until the discharge line again becomes filled with water. This cyclic operation continues, making it dimcult to regulate the aggregate gas ?ow with

beyond that desired causes a forward movement

of the aspirator plug to reduce the pulling ca pacity of the aspirator, and if the negative pres sure at the suction inlet is less than that desired, any good degree of accuracy, and in many cases 10 the plug will be moved backward to increase the varying strength of the solution produced and the pulling capacity of the aspirator. For vary the presence of some undissolved gas is objec ' ing gas ?ow rates, the water supply pressure to tionable. the aspirator and the discharge pressure remain The new invention makes it possible to have ing constant, the plug will be moved backward the variation in proportion of water flow rate 15 to increase the pulling capacity for an increased to gas ?ow rate over a comparatively wide range gas ?ow rate, and will be moved forward to de of gas ?ow-much less than when varying the crease the pulling capacity for a decreased gas pulling capacity of an aspirator‘by varying the flow rate; and with the Venturi tube and the plug operative pressure of the water, and to have the properly shaped, although the liquid ?ow may not amount of water passing through the aspirator 20 vary just proportionately with the gas flow, the always su?icient to, dissolve the gas regardless aspirator will operate with good efficiency and of any degree oi’ suction in the discharge line. the variation of the ratio of water ?ow to gas An aspirator according to the invention com-1 ?ow will be much less than with the apparatus prises 'aF'Venturi tube having a gas suction inlet . hereinbefore referred to in which the pulling ca at its throat and means for adjustably varying 25 pacity of the aspirator is controlled by varying ' the cross-sectional area of the ‘throat to vary the operating pressure of the liquid. If, for a both its pulling capacity and the liquid ?ow rate given gas flow rate and back pressure on the dis through a range extending down to a minimum charge, the liquid supply pressure varies, the throat cross-section, and for further reducing aspirator plug will be adjusted in response to the the pulling capacity without, further reducing 30 resulting variations in the negative pressure at .the throat cross-section and liquid the suction inlet in order to adjust the pulling flow rate. > As new found most desirable, the suc capacity to maintain such negative pressure con tion inlet ori?ce is in the form of an annular stant. So, also, the plug will be automatically ad- . vslot opening through‘ the throat wall, and the justed to adjust the pulling capacity of the meansadjustable for varying the pulling capacity 35 aspirator to maintain the suction inlet negative of the aspirator is a tapered member, or plug, pressure constant under pressure variations in mounted coaxially within the tube and axially the discharge line from the aspirator; and if the movable, the plug being tapered in both direc discharge line back pressure becomes sub tionsirom its zone of greatest diameter which is atmospheric to such a degree that the resulting slightly smaller than the smallest cross-section v40 suction from the discharge line in addition to of the throat. By forward movement of this that created by the aspirator increases the vac plug within its range of movement, the cross uum, or negative pressure, at the suction inlet area of the smallest or critical cross-section of above that required, the plug will be moved for; the annular throat is reduced, resulting in re ward into that range of its movement in which duction oi’ both the pulling capacity and the 45 forward movement reduces the pulling capacity ' liquid ?ow, until a point of minimum cross-area without further reduction in the flow rate of the is reached, and then by further forward move water: and the aspirator should be so designed ment of the plug the critical cross-section of that this minimum water -?ow rate is always the throat is advanced withrelation to the suc

" su?icient to dissolve the gas drawn into‘ythe

tion inlet without substantially changing the 50

water.

.

cross-area of the critical cross-section, of the

A full understanding of the invention can best throat, thereby further reducing the pulling ca be given by a detailed description of an apparatus pacity- but not reducing, or substantially reduc for supplying chlorine at a controlled rate in ing, the liquid ?ow rate. y solution in water embodying the various features In a complete apparatus according to the in 55 of the invention in the form now considered vention for drawing gas at a controlled rate into best, and of two modi?ed forms of such appara ?owing liquid embodying the automatic control tus, and such a description will now be given in feature 01' the invention, the gas: is drawn into connection with the accompanying drawings. In said drawings: . the Venturi aspirator through a passage leading from a ?ow-controlling ori?ce or passage to Fig. 1 is a diagrammatic sectional view 01' the which the gas is supplied at a controlled pressure, '

and means responsive to variations in the nega tive pressure in the passage leading to the suc } tion inlet of the aspirator controls the position

_ apparatus of the fonn now preferred;

Figs. 2, 3 and 4 are sectional views of the Venturi aspirator on a larger scale showing respectively

the adjustable plug in three di?erent positions; of the tapered plug in the throat of the aspirator 65 Fig. 5 is a cross-sectional view taken on line to vary the pulling capacity 01' the aspirator to 5-5 of Fig. 3; and

maintain said negative pressure constant. The Figs. 6 and 7 are views similar to Fig. 1 but apparatus will usually, also. include means forv illustrating modi?ed forms of apparatus. varying the ?ow rate of the gas, and for this Referring to the drawings, and ?rst to Figs. purpose the pressure under which the gas is sup 70 1 to 5, chlorine gas from a suitable source under plied to the ?ow-controlling ori?ce may be pressure, such- as a tank of’ compressed liquid varied, or an adjustable restriction may be pro chlorine, is supplied through a tube III to a pres vided in the gas flow line between the ?ow-con sure reducing valve I I of suitable construction by . trolling ori?ce and the aspirator suction inlet, which the gas is supplied at a constant substan

or means may be provided for varying. the nega- .75 ,_tially atmospheric pressure to a ?ow-controlling

2,800,642 ori?ce I2. The gas is drawn through the ?ow controlling ori?ce by the suction of a water as

pirator I5. A ?oat chamber I6 is connected be tween the ori?ce l2 and the aspirator by passage I1 from the ori?ce to the ?oat chamber and .

passage l8 from the ?oat chamber to the aspira tor, and the outlet I9 from the ?oat chamber to the passage I8 is restricted by a ?oat-controlled valve 20. In operation the aspirator maintains a

.3

?ow rate is e?ected by adjustably changing the negative pressure in this-chamber. As shown, the over?ow outlet 21 is positioned at approximately the normal operating level of the water in the ?oat chamber. With the over?ow outlet so posi

tioned, the same degree of vacuum will be main tained in the‘ ?oat chamber and passage ll as is‘ established in the chamber 30. Any suitable means may be provided for pro partial vacuum, or negative pressure, in the pas- 1 2 ducing the desired degree of vacuum in the _ sage 18 which exceeds the negative pressure de chamber 30 and for varying the degree of vacu sired on the down stream side of the ori?ce l2, .um either automatically or at will. As shown, and the exact negative pressure transmitted to the water discharge tube 3| is a vertical tube ' the ori?ce is determined by the restriction at the large enough sothat the amount of water over valve 20. , ‘~ ?owing from the outlet 21 will not cause the tube The valve 20 is, in the apparatus shown in Fig. to run entirely full and yet small enough so that 1, automatically controlled to maintain constant the tube will be sealed and that air will be car the desired negative ‘pressure in the passage l1, ried down with the water. A partial vacuum is and, therefore, the desired pressure drop across ‘ thus produced in the chamber 30; and the degree the ori?ce l2, and the operation of the valve of vacuum so produced is determined by the controlling means is adjustable for changing the =20 depth of submergence in the water in chamber negative pressure transmitted to the ori?ce to 30 of the discharge end of an air inlet tube 32. change the drop in pressure across the ori?ce Air from the tube 32 bubbles up through the wa . and thereby the rate of ?ow of the gas; and the ter when the degree of vacuum in the chamber operation of the aspirator is automatically con 25 is greater than that corresponding to the depth

trolled to adjust its pulling capacity to maintain the desired negative‘ pressure in the passage 18. Water is raised in the ?oat chamber l6 against

a negative head by the negative pressure, or par

of submergence of the discharge end of the tube, and such air is carried out through the vacuum

creating discharge tube 3|. The depth of sub

mergence of the discharge end of tube 32 will tial vacuum, in the chamber, and the valve 20. 30 thus be the measure of the degree of vacuum the position of which determines the negative maintained in chamber 30, and this vacuum may pressure maintained in the chamber and trans be varied by varying the depth of submergence mitted to the ori?ce, is controlled by a ?oat 2| of the discharge end of the tube. To provide forv in the chamber to which as shown in Fig. 1 the such adjustment, the tube 32 is a vertical tube valve'is directly connected. If the negative pres slidablyadjustable through a stui?ng box 33 in sure in the chamber | 6 exceeds the negative head the top wall of the chamber 30. The drop of the against which the water is raised in the “cham tube 3! should be su?lcient to produce a degree ber, the water level in the chamber rises and the of vacuum in chamber 30 in excess of any re ?oat is raised and the valve is given a closing quired in the operation of the apparatus. movement to increase the resistance to out?ow If the gas is supplied to the control ori?ce l2 of gas from the chamber and thereby reduce the at just atmospheric pressure and the ‘over?ow vacuum within the chamber and passage l1, and _ outlet 21 is positioned at- the operating level of if the degree of vacuum is less than said negative the water in the ?oat chamber, the drop in pres head the water level falls and the ?oat moves sure across the ori?ce I2 will be equal to the de~ downward and the valve is given an opening gree of vacuum maintained in chamber 38, and movement to reduce the ?ow resistance through the depth of submergencelof the end of the air the outlet, therebyoincreasing the vacuum in the tube 32 in inches will be the measure of the chamber and passage IT. The negative head drop in pressure across the ori?ce as expressed against which the‘ water is raised by the negative in inches of water. If the gas is supplied to the pressure in the chamber thus determines the de . ori?ce at a pressure slightly below atmospheric gree of vacuum, or negative pressure, maintained pressure, then in order to obtain a given pres in the chamber, and, therefore, the drop in pres sure drop across the ori?ce, the degree of vacuum ‘ sure across the ori?ce and the ?ow rate ‘of the maintained in chamber 30 should be increased by _

gas.

The ?oat chamber is supplied with a constant small ?ow of water through a tube 23 from a

suitable source of supply, the ?ow to the chamber being controlled. most‘ desirably, by a constant ?ow rate valve 24, and the water flows from the chamber through a downwardly extending tube

an amount equal to the negative pressure under .

which the gas is supplied to the over?ow outlet should be lowered a number of inches; and if the gas the ori?ce at a pressure slightly

ori?ce or the corresponding is supplied to above atmos

, 25 which connects to an upwardly extending tube

phere, then for obtaining the,given pressure drop across the ori?ce the degree of vacuum main-;

26 to form a U-tube. From the over?ow outlet 21 at the top of tube 26 the water falls into a chamber 30 from which it ?ows to waste through a tube 3|. The negative head against which the water is raised in the ?oat chamber by the nega tive pressure in the chamber will thus depend on

over?ow outlet 21 raised accordingly. The means shown and above described for producing a desired negative head against which the water is raised in the ?oat chamber and for varying such negative head is disclosed and

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i th

over?ow outl t 21 and the -

tained in chamber 30 should be reduced or the

claimed in Patent'No. 2,158,976, dated May 16,

the pressure eleva'non at o thee outlet. Instead e of varying ‘ . 1939. granted on my co-pending application air this negative head by varying the elevation of the ‘*Serial No. 96,242. Means such as shown in said over?ow outlet, the over?ow outlet 21 is, in the To 'co-pending application for power-operating the construction shown, ?xed and the chamber 30 is valve 20 under control of the ?oat instead of hav

a closed chamber, and the desired negative head

is obtained by establishing a suitable negative pressure in this chamber, and desired change in the negative head and resulting change in gas I

ing it operated directly by the ?oat maybe used to obtain greater accuracy and steadiness in maintenance of the desired negative pressure in the ?oat chamber and passage ll.

2,800,842 Water is supplied under suitable pressure to the aspirator l5 through an inlet pipe 40 and discharged with the induced gas through a de livery pipe 4| which may extend upward or _ downward from the aspirator and deliver into

water or other liquid under pressure or not, so that the discharge from the aspirator maybe against a negative head or may be against a

end of the tapered entrance portion the‘ .pas sage is, in the particular form 'of aspirator shown, cylindrical. The block 45 is connected at its intake side 'to the inlet pipe 40 and at its‘ opposite side has connected to it a short out wardly tapering tube 48 which forms the outer portion of the diverging pressure building por tion of the Venturi passage, and to the far end

ofwhich the delivery pipe 4! is connected. positive head provided the operating pressure under which the water is supplied to the aspira 10 The adjusting member is in ‘the form’of a plug 50 which is tapered both forwardly and rear-v tor is su?lciently greater than theback pressure The aspirator l5 consists essentially of means

wardly from’a zone or part of greatest diameter which is slightly less than the diameter of the

in the direction of ?ow of the water and an an nular gas inlet at or just beyond the small end

through an opening in a boss at an elbow of the inlet pipe 40 and through a stu?ing box 52, so

on the aspirator.

cylindrical portion of the passage in the block providing a passage for the water having an entrance portion which tapers from large to small 15 45. The plug is carried by a rod 5i which extends that it is movable endwise for adjusting the plug 50 axially in the throat of the Venturi tube. passage, the greatest diameter of which member 20 For holding the plug in coaxial position within the tube, it is provided with three guide ?ns 53 is slightly less than the smallest diameter of the which extend with an easy ?t to the walls of passage, and which is adjustable axially for vary the cylindrical portion of the tube. The tapered ing the minimum cross-area of the annular space inner portion of the plug 50 co-acts with the between the plug andthe passage wall until by forward movement itsportion of greatest diam 25 tapered entrance portion 01' the bore of the block 45 to form the entrance portion of the eter is at the small end of said tapered entrance Venturi passage for converting pressure energy portion of the passage, and may be adjustably moved further forward to move its portion of , of the water into velocity energy, and the tapered outer end portion of the plug co-acts with the greatest diameter past the annular gas inlet so that the minimum cross-area of the annular 30 cylindrical portion of the bore through ‘the block 45 ‘to form the inner end portion of the diverging 4" flow-way is not substantially changed but the pressure-building part or the Venturi passage critical cross-section of the throat is advanced which is continued by the outwardly expanding , with respect to the gas inlet. The aspirator is

of such tapering portion, and a tapered adjust

_ ing member mounted concentrically within the

tube 48. . in effect a Venturi tube with a gas inlet at its throat and having an adjustable member, or plug, 35 In Fig. 2 the adjusting plug 50 is shown in a“: withdrawn position for maximum water ?ow and extending through the throat so that the flow maximum pulling capacity of the aspirator. passage at and adjacent to the throat is an an Fig. 3 shows the position of the plug when it has nular passage, the plug and the part or parts been moved forward just far enough to reduce which forms the main wall of the passage, or a

conduit, which part or parts will hereinafter be 40 ‘the water?ow to the minimum. By adjustment of the plug between these two positions, the referred to as a “Venturi tube,” being so formed cross-area of the critical cross-section of ‘the as to provide the essentials of a Venturi tube, Venturi throat is varied, thereby varying the that is, a ?ow passage comprising an entrance ' pulling capacity of the aspirator and, with a tube portion, or cone, which tapers from large to small in'the direction of ?ow and a delivery or dis 45 of the form shown, water flow, with change in the e?lciency of the aspirator which is small as charge portion with tapers from small to large compared to the change in e?lciency of an aspi and which is joined to the entrance portion by rator‘of which the pulling capacity is varied by a throat or portion of minimum cross-section, adjusting the water supply pressure. By mov the two tapering portions being of limited angle ing the plug further forward from the position ' between the walls. As in the conventional Ven of Fig. 3, as to the position shown in Fig. 4, the turi tube, some of the pressure energy of the critical cross-section is advanced with relation water in passing through the entrance cone is to the gas inlet slot without further reducing its ’ - ‘changed into velocity energy with reduction of cross-area, whereby the pulling capacity of the pressure so that the water passes through the throat with largely increased velocity and at a » aspirator is further reduced without reducing the water ?ow rate. correspondingly reduced pressure. A suction is The shape of the walls of the Venturi passage thus created at the gas inlet, and gas entering may, of course. be varied somewhat, but it has the stream of water at the point of high velocity been found best to make them approximately as and low pressure becomes thoroughly mixed with the water as it flows on through the diverging 60 shown, that is, with the passage in the block 45 portion, or pressure cone, in which velocity en ergy oi’ the water is converted back into pres sure energy to overcome any back pressure on

cylindrical for a short distance beyond the gas inlet slot for guiding the ?ns 53, and with'the tapered entrance portion of the. outer wall and

the forwardly tapered portion of the plug con > ' As shown in the drawings, the tapered en 65 cavely tapered so that, except when the plug has been moved forward beyond the inlet slot, the vtrance portion and the throat of the bore or high velocity liquid as it passes from the critical passage ~o1~ the Venturi tube are formed in a cross-section will flow inward away from the in block 45 of suitable material, which in the par the aspirator.

let slot to leave space for the induced gas, ticular apparatus illustrated will be a material resistant to wet chlorine. The annular gas in 70 The important advantage which the new in vention has over the old method of adjusting the let ori?ce 46 is a narrow slot opening from an pulling capacity of the aspirator by varying the annular passage 41 to which the gas tube I8 pressure of the operating water applied thereto, connects, and is located just beyond the small

of maintaining a high efiiciency of the aspirator sage; and for a short distance beyond the small 75 for varying gas ‘?ow rates, is shown by the result

. end of the tapered entrance portion of the pas

2,300,642 of a carefully conducted comparative test in which both aspirators discharged against the same back pressure and the pulling capacity of both was controlled to maintain the same con stant negative pressure at the gas inlet of the

aspirator under variation in gas flow rate, the aspirator according to the invention being oper ated by water under constant pressure. With

the old style aspirator, the pulling capacity of

5

Water will thus be supplied constantly to the container ‘mat a low rate and will be withdrawn from‘~'the container through the tube 13 when there is a su?icient degree of vacuum in the gas suction tube 18 to overcome the negative head in the tube 13, the water ‘entering the tube Hi ‘from tube 13 passing into the throat of the aspirato'r together with gas from chamber iii. In the operation of the apparatus, if by the 10 negative pressure in the gas suctionpassage l8

which was varied by varying the water supply pressure, the ratio of water ?ow to gas flow in; water is withdrawn from the‘ container 10”" creased from 40 gallons per pound of chlorine through the tube 13 faster than it ?ows into the when the gas ?ow was at the rate of 6000 pounds container from tube ‘H, the weight of water in of chlorine per day to 90 gallons per pound of the container will decrease and the container chlorine (125% increase) when the gas ?ow was 15 end of the normally balanced lever 65 will rise‘ at the rate of 2000 pounds per day, and to 120 under pressure of spring 61 on the other end of gallons per pound of chlorine (200% increase) the lever and the valve 63 will be given a closing

when the gas flow was at the rate of 1000 pounds ‘

movement. By such throttling of valve 63, re

per day; while with the new aspirator, the vari sistance- to out?ow of water ‘from chamber 58 ation in gallons of water per pound of chlorine 20 will be increased, thereby raising the pressure was only between 30 and 40 (33%,% increase) on diaphragm 55 by which the diaphragm and when the rate of gas ?ow per day varied between plug rod 5| are moved upward against the pres 6000 pounds and 2000 pounds, and between 30 sure of spring 51, moving plug 50 upward, or for and 60 (100% increase) when the gas flow varied ward, in the Venturi throat, thereby reducing the‘ between 6000 and 1000 pounds per day. minimum cross-section of the aspirator throatv In the apparatus shown, the plug 50 is ad 25 and reducing the pulling ‘capacity and'water con- f justed automatically in response to variations in sumptionsoi the aspirator. This upward move-. the negative pressure in gas ?ow tube (8 to ‘ ment of the plug rod 5! will also by'upward maintain a desired negative pressure in said movement of collar 68 relieve somewhat the tube. The end of the plug rod 5| is connected 30 downward load of spring 61 on the left hand to a diaphragm 55 mounted in a diaphragm end of the lever, thus tending to balance the de housing 56 rigidly connected‘to the inlet pipe 40. creased weight of water in the container. The The housing chamber or space above the dia decrease in weight of water in the container due phragm is open to atmosphere, and a spring 51

excessive suction through the tube 13 and biases the diaphragm downward. The chamber 35 to the resulting increase in pressure'on diaphragm 55 will continue until the pulling capacity of the aspirator has been decreased to that required to plied under suitable pressure through a supply , beneath the diaphragm is a closed pressure chamber to which a small flow of water is sup

tube 60 and through a suitable ?ow-limiting

maintain a degree of vacuum or negative pres

means, most desirably a constant ?ow rate valve 40 sure in the passage l8 su?icient to withdraw water through tube ‘I3 at the same rate as water 6| which permits only a very small ?ow of water. enters the container through valve 8|. This The pressure within the chamber 58 is relieved

negativepressure will be that desired to be main by ?ow through a tube 62 and past valve 63 to tained'in passage l8 as determined by the nega waste through waste outlet 6h The pressure tive head in tube 13. relief tube 62 as shown leads from the chamber ~15 If, on the other hand, the aspirator is operat 58 but might equally well lead from the tube 60 ing with a pulling capacity insu?icient to with between the ?ow-limiting valve 6| and chamber draw water from the container ‘H! as fast as it 58 as in.the apparatus of Figs. 6 and "I. If the

enters the container, the weight of water in the water is permitted to escape freely through tube ‘ container will increase and the container end 62 no pressure will build up in the chamber 58, 60 oi’ the lever 65 will fall, thereby opening valve

but if the outflow of water is restricted pressure 63 and reducing the resistance to out?ow of will build up in the chamber to a degree depend __ water and lowering the pressure on diaphragm ent on the resistance to flow through the. valve _ 55 and permitting a decrease in the quantity of 63. in chamber 58. The diaphragm and‘ plug Valve 63 is controlled according to the suction 55swater rod 5| will then be moved downward by spring

exerted by the aspirator by means responsive to variations in the amount of water in a container to which water is supplied at a constant very low rate and from which a tube extends upward to

the gas suction passage I 8. As shown in Fig. 1, valve 63 is connected to a lever 65 pivoted at 66 '

on a support extending from the diaphragm

51 to move the plug backward in the Venturi throat, increasing the minimum cross-section of the throat and thereby increasing the pulling ca- ' pacity of the aspirator. At the same time down ward movement of the rod 5! increases the pres— \

sure of spring 61 on the left hand end of the

lever, and the lever will again become balanced housing 56. The inner or short end of the lever when the pulling capacity or'the aspirator has is biased downward by means of a spring 57 the been increased to that required to maintain a upper end of which bears against a collar 88 85 negative pressure in passage it Just su?‘icient to * ?xedly attached to the plug rod 5|. The other, withdraw water from the container at the same

long, end of the lever beyond the point of con- ‘ : nection of the valve 63 carries a container 70 to which water is supplied at a low constant rate from tube 60 through a tube ‘H and constant ?ow 70 rate valve or other suitable ?ow-limiting device 12. A tube 13 extends downward from gas suc tion passage "3 to near the bottom of the con tainer 10, the ends of both tubes ‘II and 13 hav

ing no physical‘ connection with the container.

rate that water enters the container, that is, when the negative pressure in thepassage I8 has been restored to that desired as determined

by the negative head in tube 13. The pulling capacity or the aspirator will thus be automatically adjusted to maintain the desired negative pressure in the passage I8 for drawing the gas at a rate determined by the ad

Justment of valve 26, and this automatic adjust

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2,soo,e42

ment of the pulling capacityjoi the aspirator by movement of its adjusting ‘plug 58 will follow ' either a change in adjustment of the valve 28

1 spring 8|,‘thereby throttling valve 53a and caus ing an increase of pressure in chamber 58 where by diaphragm 55 and rod 5| are moved upward

and the aspirator plug 50 is adjusted upward for changing the gas flow rate, or a change in the pressure under which water is supplied ‘5 to decrease the pulling capacity and water con through pipe III, or a change in the back pres sumption of the aspirator. The parts will come to balance when the pulling capacity of they aspirator has been reduced to that required to whether such' back pressure is positive or nega tive, all, of course within the operating range maintain the desired negative pressure in pas‘ oi.’ the apparatus. 10 sage l8, while drawing in the gas at the rate If the arrangement of the delivery pipe is such for which the ?ow-adjusting restriction formed that the aspirator dischargesiagainst a negative by valve 20a is set, the upward pull of the dia head, this negative head, or partial vacuum, in phragm then balancing the downward force of spring 84. creases the suction of the ‘aspirator on the gas passage I 8, and to compensate for this increased 15 If the aspirator is operating with a pulling suction the plug will be automatically adjusted capacity not su?icient to maintain the desired as above stated; The negative head on the dis- ' negative pressure in passage l8, the suction on charge may be so great that, because of the diaphragm 80 will be insuflicient to resist the suctiontransmitted therefrom to the gas inlet downward force of spring 84, and valves 63a ' sure against the discharge from the aspirator

ori?ce of the aspirator, the; pulling capacity of. 20 will be opened with a resulting decrease in pres the aspirator will for the then gas ?ow rate be excessive even‘ with the plug advanced to the

sure on diaphragm 55, and diaphragm 55 and rod 5| will move downward under pressure of

minimum critical cross-section position shown in

spring 51, withdrawing plug 58 and thereby in

Fig. 3. Then in response to such excessive de creasing the ilow‘of water through the aspirator gree of vacuum in the, passage l8, the plug will 25 and its pulling capacity. This increasing of the be further advanced to reduce the pulling ca pulling capacity of the aspirator will continue pacity or the aspirator without further reducing until the desired’ negative pressure is being the water ?ow until the suction on the gas inlet maintained in passage l8, the upward pull of ori?ce is reduced to that which will maintain the diaphragm 80 then balancing the downward the desired negative pressure in the passage i8. 30 pressure of spring 84. The apparatus shown in Fig. 6 diners from The pulling capacity of the aspirator of this Fig. 6 apparatus will thus be automatically ad that of Fig. 1 in that it has an alternative means for controlling the water pressure on diaphragm justed and maintained at that required to main 55 for adjusting the aspirator plug 58 in response tain a desirednegative pressure in the passage to variations in the negative pressure in the gas 35 I8 while withdrawing the gas at a rate deter suction passage l8, and that it has no means for mined by the adjustment of valve 20a, and, as automatically controlling the restriction between in the case of the apparatus of Fig. 1, this auto the howl-controlling ori?ce and the aspirator. matic adjustment of the pulling capacity of the The adjustable restriction between the gas ?ow aspirator will follow either a change in adjust controlling ori?ce l 2 and the aspirator is a hand- 40 ment of valve 28a for changing the gas flow

adjustable valve 28a by adjustment of which the rate, or a change in water supply pressure, or negative pressure transmitted to the ?ow-con change in the back pressure against the dis trolling ori?ce may be varied to vary the drop charge from the aspirator. And if the discharge in pressure across the ori?ce and thereby the is against a su?icierit negative head, the aspirator rate oi.’ gas flow, the negative pressure in the 45 plug 58 will be advanced beyond its ?rst posi gas ?ow passage 18 leading to the gas inlet tion of minimum throat cross-area to further of the aspirator being maintained constant. reduce the pulling capacity of ‘the aspirator Instead of having the valve which controls the without changing the minimum cross-area of voutlet to waste of water passing the ?ow-limit the throat, and, therefore, without changing the ing valve 8|, and thereby the pressure on the 50_ water iiow rate. diaphragm 55 for determining the position of In this Fig. 6 apparatus, the negative pressure the aspirator plug 50, controlled as in Fig. l by maintained in passage 18 is not determined, as means responsive to variations in the amount of - it is inthe apparatus of Fig. 1, by a negative water in a container the amount of water in head in tube 13, and therefore does not depend which varies according to variations in the nega- 55 on the vertical length oi.’ tube 13, but is deter tive pressure in the gas suction passage I8, this mined by the force or spring 84 tending to open valve 63a is controlled by a diaphragm 80 mount» valve 53a and working against the upward pull ed in a housing 8| which provides a closed cham of the diaphragm resulting from the negative ber above the diaphragm to which the tube 13 pressure in passage iii. The negative pressure leading downward from the gas. flow passage I8 60 in passage i8 will thus depend on the strength connects. The valve 63a is connected to the of spring 84 which is adjusted to that required diaphragm 88 by a rod 82, the valve casing ex to balance a desired degree of vacuum on the tending downward from the lower wall of the upper side of diaphragm 80. For making such diaphragm housing. The chamber beneath the vadjustment, the collar 85 is, most desirably, made diaphragm is vented to atmosphere through an 65 adjustable by being supported by a nut threaded opening 83, and a spring 84 bearing on a collar on the valve stem 82. This adjustment of the 85 on the valve rod tends to move the diaphragm force of spring 84 by changing the position of and valve downward to hold the valve in open collar 85 on rod 82 may also be made to serve position.

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the purpose of adjusting the apparatus to main

In operation, if the aspirator is operating with 70 tain different desired negative pressures in the too great a pulling capacity, so that the negative passage l8. By so varying the negative pressure pressurein the gas suction passage i8 is greater maintained in the passage l8, the gas ?ow rate 4 than the desired‘ negative pressure for which may be varied without change in adjustment of ' the apparatus is adjusted, the diaphragm .88 will ' the valve 288:, and this might be relied on for be liited . against the downward pressure of 7 varying the gas ?ow rate instead of providing

,

7.

2,300,642 an adjustable valve or restriction between ‘the ?ow-controlling ori?ce and the aspirator. The automatic aspirator adjusting means of Fig. 6 does not give quite such close adjust ment of the pulling capacity of the aspirator and such steady maintenance of a constant negative pressure in passage It as that of Fig. 1, since it does not have any reacting means such as the

diaphragm 55, permitting the diaphragm and rod 5| to be moved downward under pressure of

spring 51 to withdraw plug 50, thereby increasing the pulling capacity of the aspirator. If by adjustment of air inlet tube 32 the negaa tive head on the ?oat chamber is increased, the water level in chamber 9| and ?oat 90 will fall

untilby the resulting adjustment of vthe aspirator

spring 61 of Fig. l, the loading of which is varied plug the pulling capacity of the aspirator has by movement of the plug adjusting rod 5| to 10 been increased to increase the negative pressure dampen such movement through its action in suction passage l8 and ?oat chamber 9| to through the lever on the valve. equality-with the negative head; ‘and if the nega Fig. 7 shows an apparatus in which the ad tive head is decreased, the ?oat will rise, causing justment of the aspirator plug is controlled by an opposite adjustment of ‘the aspirator plug’to a member the position of which is determined by 15 decrease the pulling capacity of the aspirator the level of a body of water which is raised by the suction of the negative pressure in the gas suction passage working against a negative head which determines the negative pressure main tained in the gas suction passage, that is, be 20 tween the ?ow-controlling ori?ce and the as

until equality between the negative pressure and the negative head is‘ again attained. Such varia tion of the negative pressure maintainedin the passage It by varying the negative head on the water in the ?oat chamber serves for variably adjusting the gas flow rate. With this apparatus,

pirator, by varying which negative head the

also, as with the apparatus of Figs. 1 and 6, the

negative pressure maintained constant in the gas suction passage may be varied as, desired to vary the gas flow rate by varying the drop in pressure across the ?ow-controlling ori?ce.

aspirator plug is automatically adjusted to main tain the desired negative ‘pressure in passage it

As shown ,in Fig. 7, the control member of this apparatus is a ?oat 90 in a ?oat chamber

under variation in water supply pressure and under variation in the back pressure against

which the aspirator discharges. What is claimed is:

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1

9| connected between passage |'| leading from 1. A Venturi aspirator for drawing gas into a the ?ow-controlling orifice l2, to which the gas 30 stream of operating liquid, comprising a Venturi is supplied at a constant substantially atmos tube having a suction inletwfor the gas at the pheric pressure by pressure reducing valve II, throat thereof, and means adjustable for vary and a gas suction passage leading to the as ing the pulling capacity of the aspirator and the pirator. The position of the aspirator plug 50 is liquid ?ow rate by varying the cross-area of the controlled, as in Figs. 1 and 6, directly by vdia 35 critical cross-section of the throat down to a cer phragm 55 through rod 5|, pressure water being tain minimum and for further reducing the pull supplied to the diaphragm chamber 58 through ing capacity of the aspirator without substan . supply tube 60 and ?ow-limiting valve 6|. The tially reducing the cross-area of the critical pressure relief tube 621) through which the pres cross-section of its throat below said ‘minimum,

sure in chamber 58‘is relieved discharges into 40 said means comprising an adjustable member ?oat chamber 9| past a valve 63b under con within the Venturi tube. trol of the ?oat 90. The relief tube 6% has at 2. A Venturi aspirator for drawing gas into a its end within the ?oat chamber a downwardly stream of operating liquid, comprising a Venturi opening valve seat to cooperate'with valve 63b tube having a suction inlet for the gas at the carried directly by the ?oat. , throat thereof, and an adjusting member mount

As in Fig. 1, the water constantly supplied to chamber 9| through tube 621) ?ows from the. chamber through a U-tube'25, 26, the up?ow leg 26 of which discharges through an over?ow outlet 21 into a negative pressure chamber 30 from which the water ?ows to waste through a tube 3|, the negative pressure in chamber 30 being adjustable by varying the depth of sub - mergence of the end of air inlet tube 32, as more

ed within the tube and movable airially therein. by forward movement of which member to a certain point the cross-area of the critical cross section of the throat is reduced to reduce the liquid ?ow rate and the pulling capacity of the ' aspirator, and by forward movement of’ which

beyond said point the critical cross-section of the throat is advanced with relation to the suction

.

inlet to reduce the pulling capacity without substantially .reducing the liquid ?ow rate. 3. A Venturi aspirator for drawing gas into

If the negative pressure in the ?oat chamber exceeds the negative head against which the

a stream of operating liquid, comprising a Ven turi tube having a circumferential gas inlet at

fully explained in the description of the appa ratus of Fig. l.

y

water is raised in the chamber, the water level

the throat thereof, and an adjusting plug tapered

in the chamber rises and the ?oat rises and valve 63b is given a closing movement. Such throttling

in both directions from a‘ zoneof maximum di ameter mounted co-axially within the tube and

of the valve 83b causes an increase of pressure

adjustable axially therein, by forward movement

in diaphragm chamber 58 whereby diaphragm 55 of which plug to a certain point the cross-area and rod 5| are moved upward and the aspirator of the critical cross-section of the throat is re plug is adjusted upward to decrease the pulling 65 duced to reduce the liquid ?ow rate and the pull capacity of the aspirator, thereby decreasing the ing capacity of the aspirator, and by forward degree of vacuum in passage l8 and in ?oat movement of which beyond said point the criti chamber 8|. If, on the other hand, the aspirator cal cross-section of the throat is advanced with is operating with insu?icient pulling capacity so relation to the gas inlet to reduce the pulling ca that the negative pressure in passage i8 and 70 pacity of the aspirator without substantially re chamber 9| is less than said negative head, the ducing the liquid?ow rate. water level falls and the ?oat moves downward 4. A Venturi aspirator for drawing gas into and valve 63b is given an opening movement, a stream of operating liquid, comprising a Ven-' whereby the ?ow resistance from tube ‘62b is re turi tube having a circumferential gas inlet atv _ duced‘with a resulting decrease in pressure on 76

the throat thereof, and an adjusting plug tapered

8

2,300,642

in both directions from a zone of maximum di ameter mounted coaxially within the tube and

adjustable axially for varying the pulling capacity of the aspirator, the entrance portion of the Ven turi tube being taperedadjacent the throat and . the portion just beyond the gas inlet being cylin

the gas inlet of the aspirator for adjusting said valve to cause through variation in the pressure in said pressure chamber adjustment of said adjustable means to increase the pulling capac

ity of the aspirator by increasing the minimum cross-area of the Venturi throat when said neg

drical, the plug having guide fins to engage said ative pressure is less than the desired pressure cylindrical portion of the tube, and the forwardly and to decrease the pulling capacity of the as tapered portion of the plug being concavely ta pirator by decreasing the minimum cross-area pered adjacent its part of greatest diameter, and 10 of the Venturi throat when said negative pres the plug being adjustable between a position in sure is greater than desired, whereby said nega which its zone of maximum diameter is in the tive pressure is maintained substantially con entrance part of the throat and a position in the stant. cylindrical portion of the throat beyond the gas '8. The combination with ?ow-controlling inlet. means and means for supplying gas at a con 5. The combination with ?ow-controlling trolled pressure to said flow-controlling means,

means and means for supplying gas at a con

trolled pressure to said ?ow-controlling means, or a Venturi aspirator having a gas inlet at the throat thereof for drawing the gas through said ?ow-controlling means comprising a Venturi tube having a circumferential gas inlet at the throat thereof, and an adjusting plug tapered in both

of a Venturi aspirator having a gas inlet at the throat thereof for drawing the gas through said ?ow-controlling means and having means

adjustable for varying its pulling capacity _by varying the minimum cross-area of its throat, a container, means for supplying a small con

tinuous flow of water to the container, means directions from a zone of maximum diameter providing a passage from the container upward mounted coaxially in the tube and adjustable 25 to the passage between the ?ow-controlling

axially therein, by forward movement of which

plug to a certain point the cross-area of the crit ical cross-section of the throat is reduced to re

duce the liquid ?ow rate and the pulling capacity

ofthe aspirator, andraby forward movement of which beyond said point the critical cross-section

means and the gas intake of the aspirator, a

lever by which said container is carried, means for applying to the lever in opposition to the. weight of the water in the container a force ' 30 which is varied by movement of said adjusting

means, andmeans responsive to movements of‘ of the throat is advanced with relation to the gas said lever for adjusting said adjusting means inlet to reduce the pulling capacity of the aspire to increase the pulling capacity of the aspirator tor without substantially reducing the liquid ?ow when the container moves downward and to de rate; and means responsive to variations in the 35 crease the pulling capacity of the aspirator when

negative pressure in the gas passage between the ?ow-controlling means and the gas inlet of the

the container moves upward.

9. The

combination

with

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?ow-controlling

aspirator for adjusting said plug to vary the pull means and means for supplying gas at a con ing capacity of the aspirator to maintain said trolled pressure to said ?ow-controlling means, negative pressure substantially constant. 40 of a Venturi aspirator having a gas inlet at 6. The combination with ?ow-controlling the throat thereof for drawing the gas through

means and means for supplying gas at a con

said ?ow-controlling means and having means trolled pressure to said flow-controlling means, adjustable for varying its pulling capacity by of a Venturi aspirator having a gas inlet at the varying the minimum cross-area of its throat, throat thereof for drawing the gas through said 45 a container, means for supplying a small con~‘ ?ow-controlling means and having means ad tinuous flow of water to the container, means justable for varying its pulling capacity by vary providing a passage from the container upward ing the minimum cross-area of its throat, and to the passage between the ?ow-controlling means responsive to variations in the negative means and the gas intake of the aspirator, a pressure in the gas passage'between the flow 50 lever by which said container is carried, means controlling means and the gas inlet of the as for applying to the lever in opposition to the pirator, for adjusting said adjustable means to _ weight of the water in the container a force vary the pulling capacity of the aspirator by re which is varied by movement of said adjusting’ ducing the minimum cross-area of the Venturi means, a pressure chamber, means responsive throat when said negative pressure increases and to variations in the pressure in said chamber for by increasing the minimum cross-area of the adjusting said adjusting means, means for sup Venturi throat when said negative pressure de plying water at a limited flow rate to said pres creases, thereby to maintain said negative pres sure chamber, an outlet passage for said water, sure substantially constant. 7. The combination with flow-controlling 60 and a valve for controlling said outlet passage

means ‘and means for supplying‘ gas at a con

trolled pressure to said ?ow-controlling means, of a Venturi aspirator having a gas inlet at the

controlled by said lever.

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10. The combination with ?ow-controlling means and means for supplying gas at a con

trolled pressure to said flow-controlling means, throat thereof for drawing the gas through said flow-controlling means and having means ad 65 of a Venturi‘aspirator having ,a, gas inlet at the throat thereof for drawing the gas through said justable for varying its pulling capacity by vary flow-controlling means and having means ad ing the minimum cross-area of its throat, a pres justable for varying its pulling capacity'by vary sure chamber, means responsive to variations in ing the minimum cross-area of its throat, a the pressure in said chamber for adjusting said adjustable means, means for supplying water at 70 pressure chamber, means responsive to variations in the pressure in said chamber for adjusting a limited ?ow rate to said pressure chamber, an outlet passage for said water, a valve for con said adjustable means, a valve for controlling trolling said outlet passage, and means respon the pressure in said pressure chamber, a pres sive to variations in the negative pressure in the sure chamber connected to the gas intake of ' passage between the flow-controlling means and 75 the aspirator,’ and means responsive to varia~ '

9

ascents tions in the pressure in said last mentioned pres sure chamber for controlling said valve. 11. The combination with ?ow-controlling means and means for supplying gas at a con

trolled pressure to said‘ ?ow-controlling means, of a Venturi aspirator having a gas inlet at the throat thereof for drawing the gas through said ?ow-controlling means and having means ad

justable for varying its pulling capacity by vary

a pressure chamber, means responsive to varia-' tions in the pressure in said pressure chamber for adjusting said adjustable means, means for supplying water at a limited ?ow rate to said pressure chamber, an outlet passage for said water leading to said ?oat chamber, a water outl let from said ?oat chamber, means for main taining a negative head on said outlet, and a valve controlling said outlet passage and con

ing the minimum'cross-area of its throat, a 10 trolled by said ?oat to be opened by downward

pressure chamber, means responsive to variations

movement of the ?oat and closed by upward

in the pressure in said chamber for adjusting said adjustable means, means for supplying wa ter at a limited ?ow rate to said pressure cham ber, an outlet passage for said water, a valve

movement of the ?oat.

' for controlling said ‘outlet passage, a pressure

chamber connected to the gas intake of the as plrator, a diaphragm forming a wall of said last mentioned pressure chamber, and a connection

between said diaphgram and said valve. 12. The combination with

?ow-controlling

means and means for supplying gas at a con—

trolled pressure to said ?ow-controlling means, of a Venturi aspirator having a gas inlet at the

throat thereof for drawing the gas through said ?ow-controlling means and having means ad

justable tor-varying its pulling capacity by vary ing‘the minimum cross-area of its throat, a ?oat

chamber connected between the ?ow-controlling

_

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15. The combination with ?ow-controlling means and means for'supplying gas at a con

trolled pressure' to said ?ow-controlling means, ‘of a Venturi aspirator having a gas inlet at the throat thereof for drawing the gas through said ?ow-controlling means and having means

adjustable for varying its pulling capacity by 20 varying the minimum cross-area of its throat, a ?oat chamber connected between the ?ow controlling means and the aspirator, a ?oat in said chamber, a pressure chamber, means re sponsive to variations in the pressure in said 25 pressure‘ chamber for adjusting said adjustable means, means for supplying‘water at a limited flow rate to said pressure chamber, an outlet

passage for said water leading to said ?oat cham ber, a water outlet from said ?oat chamber,

means and the aspirator, a ?oat in said chamber, 30 means for maintaining a negative head on said means for maintaining water in said chamber outlet, a valve controlling said outlet passage under a negative head, and means controlled by and controlled by said ?oat to be opened by ‘

said ?oat for adjusting said adjustable means to increase the pulling capacity of the aspirator when the ?oat moves downward and to decrease

the pulling capacity of the aspirator when the ?oat moves upward. 13. The combination with ?ow-controlling means and means for supplying gas at a con

downward movement of the ?oat and closed by upward movement of the ?oat, .and means‘ for varying the negative head on the water outlet from the ?oat chamber for varying the negay tive pressure maintained in the gas ?ow passage. 16. The combination with a Venturi aspirator ' for drawing gas into a stream of operating liquid

trolled pressure to said ?ow-controlling means, .40. supplied to it under pressure, comprising a Ven of a Venturi aspirator having a gas inlet at the - ' turi tube having a suction inlet for the gas at throat thereof for drawing the gas through said I the-throat thereof, of_ a gas passage leading to

?ow-controlling means and having means ad

the suction inlet, and means responsive to the

justable for varying its pulling capacity by vary

negative pressure in said gas passage for vary

ing the minimum cross-area of its throat, a ?oat 45 ing the cross-area of the critical cross-section of chamber connected between the ?ow-controlling the Venturi throat to reduce the pulling capacity means and the 'aspirator, a ?oat in said cham of the aspirator by reducing said cross-area ber, means for maintaining water in said cham when said negative pressure increases and to in crease the pulling capacity of the aspiratorby ' ber under a negative head, means controlled by said ?oat for adjusting s'aid adjustable means 50 increasing said cross-area when said negative

to increase the pulling capacity of the aspirator

pressure decreases.

‘

1'7. The combination with a Venturi aspirator the pulling capacity of the aspirator when the for drawing gas into a stream of operating liquid ?oat moves upward, and means for varying the supplied to it under pressure, comprising a Ven negative head on the water outlet from the ?oat 55 turi tube having a suction inlet for the gas at chamber for varying the negative pressure main: the throat thereof, of a gas passage leading to tained in the gas ?ow passage and thereby the the suction inlet, a member mounted within the ?ow rate of the gas. Venturi tube and adjustable for varying the

when the ?oat moves downward and to decrease

14. The combination with ?ow-controlling means and means for supplying gas at a con

trolled pressure to said ?ow-controlling means, of a Venturi aspirator having a gas inlet at the

cross-area of the critical cross-section of the ' 60 throat, and means responsive to the negative

pressure in said gas passage for adjusting-said member to reduce the pulling capacity of the as

throat thereof for drawing the gas through said ?ow-controlling means and having means ad'-_

piratorcby reducing said cross-area when said negative pressure increases and to increase the justable for varying its pulling capacity by vary 6.5 pulling capacity of the aspirator by increasing ing the minimum cross-area of its throat, a ?oat

said cross-area when said negative pressure de

chamber connected between the ?ow-controlling means and the aspirator, a ?oat in said chamber,

creases.

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Gnomes: M. BOOTH. ‘ '