US2288437A - Air charger for storage tanks - Google Patents

Description

w. J. coNERY ETAL Am CHARGER Y Foa STORAGE LT'ANKS June 30, 1942.

Filed July 22, 1941 5 Sheets-Sheet 1 June 30,1942. w L CQNE'RY Em 2,288,437

AIR CHARGER FOR STORAGIEY` TANKS w. J. CQNERY ETAL 2,288,437 AIR CHARGER FOR STORAGE .TANKS June 30,v 1942.

Filed July 22,1941 s sheets-sheet 3 Wig 4 tems such as are Patented June 30,

UNITED isTATEs PATENT OFFICE 'causas-1^ f am casacca ron s'roaacx ranks WilliamLConeryandCarletonENewmlcx-,- Aahland,0hio.assignonto'!hel'.l.l!ym& Bro. Co., Ashland, Ohio, a corporation ot Ohio Application July 22, 1941, Serial No,4 403,508

Claims. The invention relates to water pressure sysf for vsupplying dwellings and the like, and more particularly to an air charger for use in connection with centrifugal shallow well pumps and centrifugal type deep well ejector pumps.

Such water pressure systems include a water tank which receives water from the pump and stores the water under pressure. An aircushion is maintained over the top of the water in the tank so as to force the water from the tank through the pipes of the system.

A considerable amount of watermay be drawn from the tank before the pressure is lowered materially, and as the air pressure in thev tank is lowered to a predetermined amount, the pump is automatically started and air and water are supplied to the tank until the water reaches a predetermined level and the air pressure is built up to a predetermined point.

It is common practice in such systems to provide for automatically starting the pump when the air pressure in the tank drops to pounds,

and for automatically stopping the pump whenV the air pressure reaches 40 these extremes may be varied.

It will, thus, be evident that it is necessary to maintain the air pressure within some predeterpounds, although asociated with water pumps.

when used on a centrifugal type deep well ejector Pump.

The above objects together with others which will be apparent from the drawings ,md following -description or which will be later, referredto. may be attained'by constructing the improved air charger in the manner illustraI in the accompanying drawings in which Figure 1 is a side elevation with parts broken in section showing a' shallow lwell centrifugal pump and storage tank with the improved air charger connected thereto Fig. 2, a vertical longitudinal section through the air charger showing the'same in operating position;

Fig. 3, a view similar to Fig. 2, showing the air charger in thenon-operatmg position Fig. 4, a view similar to Fig. 1, showing the air charger applied to a centrlfugalvtype deep well ejector pump; i

Fig. 5, a vertical longitudinal sectionl through the air charger as applied to the deep well pump;

mined limit's and to replenish air to the tank f as it is absorbed or lost, in` order tomaintain ,this large cushion of air in the tank.

With most types of pumps air is supplied to thetank through the pump, butl where a centrifugal type pump is used air cannot be carried through the pump with satisfactory results. For

this reason, in a pressure system' using a cen-4 trifugal type pump, it is necessary to provide 4means for supplying air to the tank without taking the air in through the suction of the pump. It is therefore, an object of the invention to provide an air charger which will automatically. supply air to the tank each time the pump is operated without drawing the air through the pump.

Another object is to provide an aircharger which will work equallywell with a shallow well centrifugal pump and with a centrifugal type ejector pump for deep wells. y

A further object of the invention is to provide an air charger which will operate equally well with either pressure or vacuum on the suction of the'pump., Y Y

A still further object is the combining oi an air charger with a pressure regulating valve l ated i and Y Fig. 6, a transverse sectional view through the air charger taken as on the line B-I, Figs. 2, 3, and 5. I

Similar numerals refer to parts throughout the several views. y

The pressure tank into which the water is pumped and stored under air pressure is indicated at i0 in Figs. 1 and 4. This tank is connected to the discharge side of the pump, which v may be a centrifugal shallow well pump Ias indicated generally at il in Fig. 1, or a centrifugal type, deep well, ejector pump as indicated generally at l2 in Fig. 4.

The suction pipe I3 of the shallow well pump li may have a check valve Il located therein as shown in Fig. l or, ifdesired, the usual foot valve may -be located at the lower end oi' the suction pipe.

Eaclrof the pumps Il accordance with usual pressure system operation by means of a motor indicated generally at i5 which is started by theusual automatic pressure switch Il mounted in direct communication w the ltank Il and constructed and operating in usual manner so that when the water level in the tank'drops to a predetermined low level the pressure switch automatically closes and starts the motor operating'the pump to deliver water 'te the tank untn 'the water level reaches a predetermined high level, at which time the air cushion above the water has been compressed suiilciently to build up pressure necand I2 maybe oper-` essary to open the pressure switch l@ stopping the operation of the motor and pump.

All of this is of usual and well-known construc= tion and operation as is also the ejector mech= anism of the pump l2 which includes the delivery pipe il having the Venturi tube lil at its lower end and the pressure pipe lll leading downward from the pump and having the upturned nozzle 2li at'its lower end for creating high velocity at the Venturi throat.

The usual-foot valve 2l is located at the lower end of the pipe, and as above mentioned this foot valve may be located at the lower end of the suction pipe i3 of the shallow well instead of the check valve shown in Fig. l.

The usual air vent valve 22 maybe yprovided upon the tanls l@ at the maximum water level so as to vent off any excess air which may ac-1 cumulate in the tank. due to the operation of the aircharging device to which the invention pertains.

This air charger is indicated generally at 253 and is in the form or" a substantially cylin-a drical housing consisting of three chambers com prising the high pressure chamber 213, the tank chamber 2h and the diaphragm or low pressure chamber it.

A plunger 2l is slidahly mounted through the bushing 2b located inthe partition wall 2@ between the tank chamber 25 and the low pressure chamber 2li, the end of said plunger .being cut away to form a plurality o vanes 3@ in substan tially cross shape so as to provide communica-= tion through the same between the several cham `bers when the plunger is in the retracted position as shownin Fig. 3.

A flexible diaphragm Si has its peripheral portion clamped between the housing and the cap St, as by the screws 33, the central portion of said diaphragm being clamped between the diaphragm holding plates or washers 3d and atan air valve 39 of the well-known type commonly used upon automobile tires. A pipe lll communicates with the tank chamber 25 and with the automatic pressure switch le.

ninternally threaded priming opening lll is formed through the top wail of the housing 23 communicating with the high pressure chamber 2Q and receives the threaded bushing l2 in which is located the threaded tube i3 of the pressure gauge lll which Yindicates the operation of the pump and the air pressure in the tank.

f An internally threaded air vent le is 'formed in the cap 32 and normally closed by the screw plug '6b. A threaded orihce lll is formed in the end of the cap 32 for receiving an orifice nt ting (lil, the purpose of which will be later described. A

A threaded opening lil is also formed in the end of the cap, in axial alignment 'with the plungerv 2l ,to receive a threaded plug 5@ when the air charger is used 'upon a shallow well pump, or the regulator spring housing l when arrears? the air charger is used upon a deep well ejector typ@ pump. v

An internally threaded drain aperture E52 is provided in the bottom wall oi the housing 28 communicating with the high pressure chamber 2d and adapted to be closed by the drain plugY when the air charger is used in connection with a deep well pump.

in internally threaded inlet noch 55 is formed upon the housing 23 communicating with the high pressure chamber 26 'and adapted to be' connected as by the pipe 5S with the discharge iside of the pump.

Y t@ and to the shut-oil valve casing Eid below the valve 53 therein, as by the compression fittings G6 and G5, respectively.

d brass nipple @his connected to the lower end of the valve casing 5G and to one end oi' a cop= per tubing el, the other end of which is con= nected as 'by the brass nipple @d directly to the intake side of the pump.

\ tank pressure.

.The valve is provided for the purpose oi priming the pump. `When. this is necessary the valve 63 is opened, the pressure gauge lid and bushing l2 are removed and the pump is lled with water through the opening lli.

The pump is then started and water is allowed to circulate until all air is carried out of the pump il and suction piping i3, after which the valve tt is closed and the pump is operated in usual manner.

The same air charger is used in connection with deep well pump as shown in Figs. l and 5, .the connections being slightly different as shown.

'When used on centrifugal type deep well ejector pumps the air charging principle is exactly the same as for the shallow well operation excepting that a pressure regulating attachment is used with the air charger.

In a deep well ejector pressure system as illustrated in Fig. i a given pressure at the ejector nozzle 2@ is required at all times to keep the pump operating; If the pressure is allowed to drop oi water will not be raised up to the' centrifugal pump 'l 2 and the ow will cease.

The object of the pressure regulating device is, therefore, to maintain a set pressure on the ejector nozzle til at all times regardless of the This pressure regulator is mounted in the housing 5l and comprises a plunger e@ slidabiy located through the bore l@ in the outer end of the cap 32 and projected into the chamber 2li.

A coil spring il is interposed between the head l2 of this plunger and the adjusting screw i3 which is adjustably mounted in the threaded bore ll in the outer end of the housing 5l, and arranged to be normally enclosed by the screw cap l5. i

In this arrangement of the invention a copper tubing @2a leads from the orifice tting it to the suction nipple lt whichis connected to the inwater to the tank I until the water reaches the maximum level indicated by the line B at which time suflicient air has been compressed in the tank above the water to build up the pressure necessary to open the switch stopping the motor and pump.

When the pump starts to operate, pressure is immediately built up in the chamber 24 of the air charger, since the only passage open for ilow of water to the pressure tank I0 is through the Venturi tube 31, and the opening through this tube being small automatically causes the centrifugal pump to operate at a high pressure.

The characteristics of the centrifugal type pump are such that as the pressure increases the tlow decreases until a point of equilibrium is reached and water flows through the Venturi tube 31 at a constant rate.

Simultaneously with the high pressure created in the chamber 24 by the pump, l/ow pressure occurs in the chamber 26 by reason of the water in the chamber 25 being released through the aperture 18 in the orifice iitting 48 and through tubing 52 and 51 to the intake side of the pump.

This differential pressure between the chambers 24 and 2E causes the diaphragm 3| to move in thedirection oi the lowest pressure, that is, toward the right as viewed in the drawings, compressing the spring 35 until ythe diaphragm 3| and plunger 21 assume the position shown in Fig. 3.

'I'he speed at which the diaphragm moves is governed by the sizeof the orifice 18 in the iitting 48. 'Ihe plunger 21 being directly connected to the diaphragm moves at the same' rate of speed as the diaphragm. l

'Ihe pressure in the chamber 24 being conl siderably higher than that in the chamber 25 causes the water to flow vthrough the Venturi vtube 31 at a high velocity creating a vvacuum at the throat of the venturi and causing atmospheric air to be taken in through the air valve 39.

This air is mixed with the water and discharged directly into the pressure tankthrough the discharge outlet 51 and pipe 58. This ow of water and air through the venturi continues until the diaphragm 3| and plunger 21 are moved to the. position shown in Fig. 3 permitting water to go directly from the chamber 24, and between the vanes 30 of the plunger to the chamber 25.

I'he pressure is then immediately'equalized in the chambers 24 and 25 reducing the iiow through the pump is operating.

AsI soon as the pump stops pressure is -completely equalized throughout the system by reason of the foot valve 2| or check valve |4 and :water then iiows back through the tube 52 or 52. to

the chamber 25 equalizing the pressure on both spring 35 to push the diaphragm and plunger back to the normal or closed position.

This cycle is repeated each time the pump operates supplying the necessary amount of air to the pressuretank I0. described is the same in both the shallow well and deep well pumps. However, when used in connection'with the deep well pump the'pressure regulator mounted in the housing 5| functions as follows:

When the pump starts the diaphragm 3| and plunger 21 move to the right as above described.

As the head of the screw 35 upon the plunger comes in contact with the spring plunger 59 of the pressure regulator the spring 1i is compressed, the amount of compression beingregulated by adjusting the screw 13.

With this arrangement pressure in the chamber 24 can be exactly maintained at any set point. The chamber 24being in direct communication with the nozzle 20 this pressure is directed posi- A tively to said'nozzle.

As the tank pressure builds up a greater force is exerted on the diaphragm 3| causing the spring 1I to be further compressed allowing the port opening -30 to become largerV reducing the friction loss through the valve at high pressure.

very important in an ejector type pump since any unnecessary friction results in reducing capacity.

From the above it will be obvious that the improved air charger worksautomatically in connection with centrifugal pumps of either shallow well or deep well type, to take inl atmospheric air between the pump and the tank and charge the air into the water .from the pump so ythat the desired air pressure may be supplied to the l tank at all times, without in any manner intertering with the operation of the pump.-

According to the provisions of the patentstatutes, we have explained the principle of our invention and described an embodiment thereof,

but we desire to have it understood that Within the scope of the appended claims the invention may be practiced otherwise than as specifically illustrated and described, as modifications may be made by those skilled in the art Without departing from the spirit of the invention, which resides in the provision of an air charger for admitting air to the water line between the discharge side of the pump and the pressure tank regardless of the detail structure by which this a pressure water and air tank, and a pressure controlled means for starting and stopping said pump, ag pipe leading from the discharge side of the pump to said tank, an air 'charger located inI said pipe between the pump and thetank,

said air charger having an open passageway and a normallyV closed passageway and means in said air charger for drawing atmospheric air into the waterstream from the pump when the pump starts to operate, and discharging the air mixed with the water into the tank, through the open passageway, a pipe connected to the air charger and to the intake side of the pump, and valve means in the Vair charger under the influence of the pump suction and subjected to the higher vpressure on the pump discharge side of' said valve means so thatsaid valve means is operated by the difference of pressures for equalizing the sides of the diaphragm 3| and Permitting the. pressure on opposltesldes of said open passage- 'Ihe operation above way for rende said air entraent inadective and for opening the closed passageway to provide a main pump discharge some time after the pump starts to operate.

2. in a fluid pressure system having a water pressure pump, an actuating means for the pump, a pressure water and air tank, and a pressure controlled means for starting and stopping said pump, a pipe leading from the discharge side of the pump to said tank, an air charger located in said pipe between the pump and the tank, said air charger having an open auxiliary passageway and a normally closed main passageway, means in said air charger for drawing atmospheric air into the water stream from the pump when the pump starts to operate, and discharging the air mixed with the water into the tank through the auxiliary passageway, a pipe connected to the air charger and to the intake side of the pump, and. valve means in the air charger under the influence of the pump suction and subjected to the higher pressure on the pump discharge side of said valve means so that said vvalve means is operated by the diierence of pressures for equalizing the pressure on opposite sides of said auxiliary passageway for rendering `said air entrainment inedective and for opening the main passageway to provide a main pump discharge some time after the pump starts to operate.

3. In a iiuid pressure system having a water pressure pump, an actuating means for the pump, a pressure water and air tank, and a pressure controlled means for starting and stopping said pump, a pipe leading from the discharge side of the pump to said tank, an air charger located in said pipe between the pp and the tank, said air charger having a noally closed passageway and means including a Venturi tube and an air valve in said air charger. for drawing atmospheric air into the water stream from the pump when the pump starts to operate, and dis-a charging `the air .mixed with the water into the tank, through said `Venturi tube, a pipe connected to the air charger and to the intake side ofthe pump and valve means in the air charger under the influence of the pump suction and subjected to the higher pressure on the pump discharge side of said valve means so that said valve means is operated by the difference ci pressures for equalizing pressure on opposite sides of the Venturi tube for rendering said air entrainment inedective and for ope the closed passageway to provide a main pump discharge some time after the pump starts to operate.

d. lin a uid pressure system haa water pressure pump, an actuating means tor the pump,

a pressure water and air tank, and a pressure controlled means for starting and stopping said pump, a pipe leading from the discharge side of the pump to said tank, an aircharger located in said pipe between the pp and the tank, said air charger having a normally closed pas= sageway and means inclu a Venturi tube and air valve in said air charger oridrawing latmospheric air into the water stream from the pump when the pp starts to operate, and

` dlscha the air mixed with the water into the tank through the Venturi tube, a pipe con-- nected to the air charger and connected to the intake side oil 'the pump and valve means in the air charger under the uence of the pump suction and subjected to the higher pressure on the pump discharge side oil said valve GMD means so that said valve means is operated by i713 spear-ier' the difference of pressures 'for equaliaing the pressure on opposite sides of said Venturi tube for rendering said air 'entrent ineffective and for opening said normally closed passageway to provide a main pump discharge sometime after the pump starts to operate.

5. In a uuid pressure system having a water pressure pump, an actuating means for the pump, a pressure water and air tank, and a pressure controlled means ior starting and stopping said pump, a pipe leading from the discharge'side oi the pump to said tank, an air charger located in said pipe between the pump and the tank,

there being a high pressure chamber in the aircharger connected to the discharge side of the pump and a tank chamber connected to the tank, and a normally closed port between said chambers, plunger means normally closing said port, a Venturi tube normally forming the onlyl communication between the high pressure. chamber and the tank chamber oithe air charger and an air valve counicating with the Venturi tube for drawing atmospheric air into the water stream from the pump when the pump starts to operate and discharging the air mixed with the water into the tank, a pipe connected to the air charger and connected to the intake side of the pump so that said plunger means is under the inuence of the pump suction and subjected to the higher pressure on the pump discharge side of said plunger means and so `that said plunger means is moved by the dierence of pressures for equalizing the pressure in said chambers for rendering said air entrainment ineffective and for operating said plunger means to provide a main pump discharge some timeV after the pump starts to operate.

6. ln a :duid pressure system having a water pressure pump, an actuating means for the pump, a pressure water and air tank, and a pressure controlled means or starting and stopping said pump, a pipe leading from the discharge side of the pump to said tank, an air charger located in said pipe between the pump and the tank, there being a high pressure chamber in the air charger connected to the discharge side oi' the pump and a tank ober connected to the tank and a normally closed port between said chambers, a Venturi tube normally og the only communication between the high pressure chamber and the tank chamber of the air'charger and an air valve counicating with the Venturi tube for drawing atmospheric air into the water stream from the pump when thepump starts to operate and discharging the air mixed with the water into the mi and means including diaphragm and plunger means controlling said' port and a pipe connected to the air charger and to intake side of the pump so that said dlaphra and plunger means is under the inuence of the pump suction and subjected to the higher pressure on the pump discharge side of said diaphragm and plunger means and so that. said diaphra and plunger means is moved by centrifugal type deep lwell ejector pump i'or supplving liquid to the tank, a pipe lea from the discharge side of the pp to the tank, anV

air charger'A located in said pipe between the pump and the t said air charger having an open passageway and a no clo'sed pasfaasaasv lsageivay, means in said air charger for drawing atmospheric air into the water stream from the pump when the pump starts to operate and discharging the air mixed with the water into the tank, diaphragm and plunger means in thev air charger controlling the normally closed passageway and a pipe communicating with the air charger and with the intake side oi.' the pump so that said diaphragm and plunger means is under the inuence of the pump suction and subjected to the higher pressure on the pump discharge side `ot said diaphragm and plunger means, and so that said diaphragm and plunger means is moved by the diierence of pressures for equalizing pressure on opposite sides of the open passageway and operating the diaphragm and plunger means to open the closed passageway and provide a main pump discharge some time after the pump starts to operate, and a pressure regulator for controlling the operation of the diaphragm and plunger means.

centrifugal type deep well ejector pump for supplying liquid to the tank, a pipe leading from the discharge side of the pump to the tank, an air charger located in said pipe between the pump and the tank, said air charger-having an open passageway and a normally closed passageway, means in said air charger for drawing atmospheric air into the water stream from the pump` when thepump starts to operate and discharging the air mixed with the water into the tank, diaphragmv and plunger means in the air-charger controlling the normally closed passageway and a pipe communicating with the air charger and.

with the intake side of the pump so that said diaphragm and plunger means is under the inuence of thepump suction and` subjected to the higher pressure on the pumpdischarge side of said diaphragm and plunger means and so that said diaphragm and plunger means is moved by the diilerence of pressures forequalizing pressure on opposite sides of the open passageway and operating the diaphragm and plunger means to open thel closedpassageway and provide a main pump discharge some time after the pump starts to operate, a pressure regulator for .con-

trolling the operation of the diaphragm and plunger means, and' means for adjusting the pressure. regulator.

9. In a iluid pressure system having a tank, a

8. In a iluid pressure system havinga tank, a j

centrifugal type deep well ejector pump for sup- Flying liquid to the tank, a .pipe leading from the discharge side ofthe Pump to the tank, an air charger located in said pipe between the pump and the tank, said air charger having an l open passageway and a normally closed passageway, means in said air charger for drawing atmospheric air into the water stream from. the' pump when the pump starts to operate and disfor equalizing pressure on oppositesides of the open passageway' and operating the diaphragm vand plunger means to open the closed passagetime after the pumpstarts to operate, and a pressure regulator for controlling the operation o! the diaphragm and plunger means, saidpressure regulator including a spring' pressed plunger.

l0. In a fluid pressure system having a tank, a pump for supplying liquid to the tank, a pipe leading from the discharge side ci the pump to the tank, an air charger located in said pipe between the pump and the tank, means dividing said air charger into a high pressure 'chamber communicating withthe discharge side of the pump, a tank chamber communicating with rthe tank and a low pressure chamber, a pipe from the low pressure chamber communicating .with the intake side of the pump, a Venturi tube forming communication between the high pressure chamber and the tank chamber, an air valve communicating with the Venturi tube for admitting atmospheric air thereto, there being a port between the' high pressure chamber and the tank chamber, a plunger for normally closing the port, a diaphragm in the low pressure chamber and connected to said plunger, and spring means for holding the plunger in closed position when the pump is not operating, so that when the pump starts to operate water under pressure from the high pressure chamber will pass through the Venturi tube. to the Itank chamber drawing in air from the air valve, after which the diaphragm will be moved withdrawing the plunger and opening thev port. j

'11. In a iiuid pressure system having a tank, a centrifugal type deep well ejector pump for supplying liquid to the tank, a pipe leading from the discharge side of the pump to the tank, an air charger located in said pipe between the pump and the tank, means dividing saidair charger into a high pressure chamber communi- -cating with the discharge side oi the pump, a

tank chamber communicating with the tank and a low pressure chamber, a pipe fromthe low pressure chamber communicating with the intake side of the pump, a Venturi tube forming communication between the-high pressure chamber and the tank chamber, an air valve communieating with the Venturi tube for admitting atmospheric air thereto, there being a port between the high pressure chamber and the tank chamber, a plunger for normally closing the port,

a diaphragm in the low pressure chamber *andl connected to said plunger, and spring means for holding the plunger in closed position when the pump is not operating, so that-when the pump starts to operate water under pressure from the high pressure chamber will pass through Athe Venturi tube to the tank chamber drawing in air through the 'air valve, after which the diaphragm will be moved withdrawing the plunger and opening the port, and a pressure regulator for controllingthe operation of the diaphragm "and'plungen l2. Ina fluid pressure system having a tank, a centrifugal type deep well ejector pump for supplying liquid to the tank, a pipe leading'from the dischargeside of the pump to the tank, an air charger located in said pipe between the pump and the tank, means dividing said air charger into a high pressure chamber communicating with the discharge side of the pump, a

tank chamber communicating with the tank and a low pressure chamber, a pipe from the low pressure chamber communicating with the intake sida oi the pump, a Venturi tube forming communication between the high pressure chamway and provide a main pump discharge some -ber and the tank chamber, an air valve cornthe low pressure i1 se.; @o

municating `with the Venturi tube for im: atmospheric airy thereto, there being a port be=Il tween the high pressure chamber and the tanls chamber, a plunger for normally closing the port, a diaphra in the loir pressure chamber and connected to said plunger, and spring means for hol the plunger in closed position when the pump is not operating, so that when the pump starts to operate, water under pressure from the high pressure ober will pass through the Venturi tube to the t chamber drawing in air from the air Valve, after which the diaphre will be moved withdrawing the plunger and open ing the port, and a pressure regulator for contro the operation of the diaphragm and plunger, said pressure regulator including a spring pressed pl r.; rf er.J

i3. in a uuid presume system haring a tank, a pp ior supp liquid to the tenir, a pipe lea from the discharge side of the' pump to thetanh, an air charger located in said pipe "oetween the pp and the tank, means m...-

fsaid air charger into a high pressure chamber communicating rrithjthe discharge side oi the pump, a tenir chber eo unicating with the tants and a lou7 pressure chamber, a pipe trom '-rl. unicating `with the intake side oi the pump, a normally closed valve for proyig counication between the high pressure ch ber and said pipe. a `Venturi tube :muy counication between the high pressure c ber andthe tank chamber, an 'air Valve .e unicating with the Venturi tube for u.. :n.1 atmospheric air thereto, there being 1.1.1 and zo. a 12:11-' for norm closingv the port, a diaphragm in the low pressure chamber and connected to said plunger, :and spring means ior hol the plunger in closed position when the when the pump starts to operate Water pressure from thehigh pressure chber Einer Will pump is not operating so thatthe low pressure chber counicating with, the intalre side of the pump, a Venturi tube #zu s n unication between the high pressure chamber and the tank ober, an air valve communicating with. the Venturi tube for reu; atmospheric air thereto, there being a port between the high pressure chamber and the tank chamber, a plunger for normally closing the port, a diaphragm in the low pressure charnber and connected to said plunger, and spring.'

i and opening 'the port, there being an orice in the pipe lending rom the low pressure chamber to the intake side of the pump, the size of said' orince controlling the speed ofA movement ci the plunger. i

, i5. lln'a huid pressure system having a water pressure pp, an actuating means for the pump, a pressure water and air tank, and a pressure controlledmeans ior starting and stopping said pump,` a pipe leading fromthe discharge side ci the pump to 'isaid` tanln: anhir charger located in said pipe'between the -pumpand the tank,

pass through the Venturi tube to the tanh chamber in air; troml the air valve, after winch the diaphra `will be moved withdrawing the plm-iger m10] ein," the EJUE' le, in a huid pressure system having a tanlr, a I

pp for @rrwr liquid to the tank, a pipe leading from the discharge sideioi the pump to the tenir, an air charger located in said pipe hetween the pp and the tank, means dividing said air charger into a high pressure l-.rro cunica with the discharge side or the p a tank ober eounica with the and a loir premiare chamber, a pipe from there being a high pressurefchamber-in the air charger connected' to they discharge "side of the pump and a tank chamber connected to the tanlr and a normally closed passageway between said chbers, vali/e means normally closing said passageway,l a Venturi tube normally forming the only counication between the high pressure chamber andthe tank chamber of the air charger, an air valve communicating with the `ieuturi tube-for drawing atmospheric air into the water stream trom the pumpl when the pump starts to operate and discharging the air mixed with the water into the tank through the. Venturi tube after which saidvalve means will be moved .in said normally closed passageway,a pipe leading from the high pressure chamber to the inlet side of the pump and a Valve in the pipe between the high pressure chamber and the pump inlet so that the pump will be self-priming when said valve is opened by reason oi re-circulation of water from the discharge rside of the pump through the high pressure chamber ofj the air.

charger to the intake side of the pump.

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