Residential Pumps

8/9/2019 Residential Pumps

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Residential Pump Fundamentals

2001 Goulds PumpsEffective August, 2001 www.goulds.com

Goulds Pumps and the ITT Engineered Blocks symbol areregistered trademarks and tradenames of ITT Industries.


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Sources of Water

25 ft.

25 ft.

Driven Well Drilled Well Dug Well Cistern Spring, Lake, orSurface Water

A Shallow WellIs any source of water where the water is within 25 feet of ground level. When water is pumped from a well thewater level will draw down. The lowest level to which it will drop is the level from which it must be pumped.

A Deep WellIs any source of water where the low water level is more than 25 feet below the ground level.

Driven Well Drilled Well Dug Well

Static Level

PumpingLevel

DrawDown

2

A source of water or a well is often referred to as shallow or deep. Theseterms are referring to the depth of the water source or well.A shallow well is one where the water is within 25 feet of the ground surface.A deep well is where the static water level is more than 25 feet down.The standing water level in a well is called the static level. This is the waterlevel when the pump is not operating. When the pump comes on and isrunning there often is a change in the water level. This is referred to as

drawdown. The drawdown occurs and the water level reaches what isreferred to as the pumping level. This is the operating level of the pump.The lowest level to which the water will drop is the level from which itmust be pumped.


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Pump Types

Use checkvalve hereor foot valveat end ofsuction pipe.

Typical Goulds Jet Pump Installations

SHALLOWWELL SYSTEM

TWIN PIPEDEEP WELLSYSTEM

PACKERDEEP WELLSYSTEM

2-PIPEPITLESSADAPTER

AW 42 ADAPTEROVER THE WELL

Shallow Well Jet PumpIn a shallow well jet system,the jet assembly is fastenedto the outside of the centrifu-gal pump as illustrated. Orthe jet assembly can be builtinto the centrifugal pumpcasing.In either case there is onlyone pipe extending into thewell or source of water the suction pipe.

Deep Well Jet PumpA deep well jet system isbasically the same as ashallow well system withone major difference:the jet assembly isseparate from thecentrifugal pump,located in the well,usually below thepumping level of thewater, and piped to thecentrifugal pump withtwo pipes. A suctionpipe and a pressure ordrive water pipe.

3

Typical Jet Pump Installations


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Pump Types (continued)

Goulds 4"submersiblepump with alightning

protectedmotor. Two orthree wiremodelsavailable.

Offers water storage forfewer pump cycles.Provides air cushion tooperate against. Tankshould be sized so thatdraw down is equal tocapacity of pump.

GouldsPumps

Typical Submersible Pump Installation

Pressure Tank


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The 3 BasicQuestions

1 Capacity NeededHow big must the pump be?

2 Well ConditionsIs a shallow or deep well pump needed?

3 Discharge ConditionsHow much pressure is needed?

The illustration above poses a typical water system problem. The source of water is in nearly allcases lower than the house or building. This is why a pump is needed to raise the water upto the faucets and fixtures. These are the three questions to be considered:

1 Capacity NeededHow much water in gallons per hour or gallons per minute are needed? This determines what size pump to use.

2 Well ConditionsWhat is the total suction lift? What is meant by total suction? We learn from this what to expect from a shallowwell pump and when and why to use a deep well pump.

3 Discharge ConditionsHow much pressure is needed at the pump? How much pressure will result at the faucet?

Whenever and wherever a pump is to be used, the correct answers to these three questions will tell the actualpumping conditions or specifically what is required of the pump. With this information, you can always selectthe right pump from the catalog.

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1 Capacity NeededHow much water is available?How much water is needed?How large must the pump be?

Limiting FactorsHow much water isavailable? Before weselect a pump based onneed we must determineif the supply is adequate.Many areas have what werefer to as low yield wells,Well recovery rates may beas low as 1 GPM or less.A typical low yield (1 2GPM) well, cannot supplythe 10-12 GPM requiredby an average home. If wepump at 12 GPM and thewater enters the well at2 GPM we will soon runthe pump dry. This systemwould require a pumpprotection device to turn

the pump off when it runsout of water.Fortunately some lowyield wells have a greatdeal of water stored in thewell due to high staticwater levels. There are500' deep wells with staticwater levels, when notbeing pumped, of 20'. A4" well casing storesapproximately .652gallons per foot or 1.4gallons per foot in a 6"well. In this case, a 4" wellstores 312 gallons and a6" stores 672 gallons. It ispossible to use a 7 or 10GPM pump and not overpump the well due to thelarge amount of waterstored in the casing. Whilelawn watering and daily

multiple loads of laundryare out of the question,this application couldprovide a cost effective,reliable water supplywithout the use of largeexpensive storage tanksand booster pumps. Thecustomer should be madeaware of the limitationsof the well and theoptions available.If using a deep well jetpump in a low yield wellyou should use a 34' tailpipe on the bottom of the

jet assembly. This willprevent over pumping adeep well. See the sectionon Using Tail Pipes in the

Technical Manual of yourcatalog.

Tail Pipe

Foot Valve

2" Casing

4"

Sub

WellToo Small

2"Casing

Low WaterLevel

200'

6

34'

Jet Assembly

Another weak wellscenario is to select asubmersible pump sizedfor a maximum pumpingdepth somewhat less thanthe actual depth at whichthe pump will be installed.It will then be impossiblefor the pump to overpump the well and rundry. Another option is toinstall a low water levelcut off system withelectrodes to turn thepump off at a predeter-mined level. It can be setup to automatically resetwhen the water level rises.Unlike totally electronicprotection devices theelectrodes must beinstalled in the well.If the source of supply isa deep cased well, thecasing diameter anddepth to water arelimiting factors in howmuch water can bepumped. A 2" casingcannot accommodate asubmersible pump. A2" diameter limits you to adeep well jet pump with a

packer or single pipesystem. A 2" packersystem can supplyapproximately 3.3 GPMfrom a 200' water level at30 PSI. However, asubmersible pump in a4" diameter, 200' deepwell can easily supply over60 GPM at 60 PSI. There-fore, we can see that smalldiameter wells limit theavailable flow that can be

supplied. Small diameter,deep wells equal lowcapacity pumps. They alsodictate the pump stylethat can be used.Example:Customer has a 2" wellcasing with a 100'pumping level. What isthe correct pump andwhat will it produce?The maximum pumpcapacity is about 9 GPMusing a 2" packer assem-bly with a 2 HP, 2 stage

jet pump.In cases where we have nolimiting factors, where wehave all the water re-quired and a well that will

accommodate a reason-ably sized pump. We canproceed to determine thecorrect capacity needed tosatisfy the customersrequirements.

Physical Restrictions


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DemandThe capacity required ofthe pump is determined bythe number of continu-ously flowing demands(showers, sprinkling, fillinga tub or stock trough, etc.)which are likely to be in useat the same time withconsideration given to a

minimum rate of flow fromeach of these outlets whichcan be considered assatisfactory

Approximate WaterSupply RequirementsHome FixturesFilling Ordinary Lavatory 2 gal.Filling avg. Bath Tub 30 gal.Flushing Water Closet 6 gal.Each Shower Bath Up to 60 gal.Dishwashing Machine

15 gal./loadAutomatic Laundry Machine

Up to 50 gal./load

Backwashing Domestic WaterSoftener Up to 100 gal. Yard Fixtures

1 2" Hose with Nozzle 3 gpm3 4" Hose with Nozzle 5 gpmLawn Sprinkler 2 gpm

The capacity of a watersystem or pump deter-mines its size. The bigger itis, the higher its price.Consequently, in manycases the smallest size

available is used and manyusers are dissatisfied withthe results. They eithercant take a shower or fill atub while sprinkling thelawn, or if a toilet is flushedwhen taking a shower, theshower diminishes to adribble, or some similarinterruption occurs. Thetrouble of course is that thetoo small pump cantdeliver water fast enoughto supply the demand itscapacity is too little.Determining how muchcapacity is required is notan exact science. Theobjective is to provide awater service similar to that

available from a good citywater system. This providespractically an unlimited rateof flow from any or all thefaucets or other outletseither one at a time or allused at the same time. Ahome water system canprovide this type servicebut there are few domesticwell that will furnish such aquantity and it isnt at alllikely that all the faucets in

a home will be openedwide at the same time.It can be assumed that inthe average home any twofaucets or outlets may beopened at once. The pumpmust have sufficientcapacity to supply them.This will prevent thedifficulty of not being ableto use the shower whenthe kitchen sink is in use,and vice versa.

The rate of flow from afaucet or fixture dependson its type and size, thelength and size of pipesupplying it and thedifference in elevationbetween it and the pumpor tank. Furthermore, it isimpossible to determine bysight the exact rate of flowbeing delivered from afaucet.It has been determined bytest and by observationthat the smallest orminimum rate of flow froma faucet should be aboutthree gallons per minute(3 GPM). Any less than thisapproaches what appears

to be a dribble; somewhatmore is much moresatisfactory. According tothis, if a pump or watersystem in a home is tosupply two faucets oroutlets such as a showerand a kitchen sink at thesame time, its capacityshould be two times threeor six gallons per minute(360 gallons per hour).

This of course is not alwayspractical. The capacity ofpumps changes withpumping conditions suchas pumping level of thewater and the operatingpressure. Accordingly, it isgood practice to provide apump capacity for theaverage home of from 10to 12 gpm when available.The water from the pumpor tank will not necessarilyflow to fixtures or faucetsat the rates just discussed.This is determined by theresistance to water flow inthe house plumbing and isexplained in the third stepof the procedure Dis-

charge Conditions. Itshould, however, beobvious now that in orderto use water from morethan one outlet at a time,the capacity of the pumpshould be greater than therate of flow in GPMavailable from any onefaucet.

Pipingkitchen sink to showerhead equivalent length 20'

Pipingpump tank to kitchensink, equivalentlength 30'

23'

20'

10'

30'

Staticwater level,pump notrunning

Pumpingwater level,pumprunning

Shower in use same time as kitchen sink faucet on.

2 continuous uses require 6 G.P.M. minimumThe capacity required ofthe pump is determined by the number of continuous useoutlets in use at the same time. You can't use water at one or a number of outletsany faster than the pump supplies it.

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2 Well Conditions

The level of the water tobe pumped is practicallyalways below ground. Itcan be only a few feet asin a spring, shallow well,pond, etc., or it can bemany feet as in a deepwell. If we could alwayslocate the pumpingmechanism in the water,as we do with submers-ible pumps, our problemwould be simpler becausethen the water wouldflow into the pump.However, standard electricmotors and switches arenot designed for sub-merged operation.Therefore they must belocated above ground.This poses the question:How does the water getinto the pump?We call it suction, butwhat is it? What actuallymakes the water flowuphill into the pump?How high can we raisewater by suction?1. The atmosphere allaround us has weight andtherefore exerts pressure

equal to about 14.7 lbs.per square inch at sealevel. When the pressureof atmosphere is removedfrom inside of a pump theresulting condition is avacuum or partialvacuum. It is also calledsuction.The vacuum or suctionchamber of a pump ispiped (suction pipe) to asource of water. Thesurface of the watershould be exposed to thepressure of atmosphere.When the pump operatesit develops an unbalancedpressure condition due tothe suction or vacuum it

produces. This unbal-anced pressure (14.7 lbs.per sq. in. atmosphericpressure on the surface ofthe water with vacuum orabsence of pressure in thepump) causes water fromthe source to flow up thesuction pipe into thepump. From this we can

determine how highwater can be raised bysuction.First, lets consider termsof measurement and theirrelation to each other.Pressure is usually ex-

pressed in pounds persquare inch (PSI).Pressure is used to raisewater to a height ex-pressed in feet. Thisheight is also expressed asfeet head.Vacuum is measured witha vacuum gauge. Thegauge can be calibratedin feet suction lift orinches vacuum.

A. 1 inch vacuum equals1.13 feet suction.

AtmosphericPressure

14.7 LBS.

Water Level

Atmospheric Pressure

Try to lift soda from a bottle byclosing your mouth over themouth of the bottle. It cant bedone. When you use a straw, it iseasy you are creating a partialvacuum in your mouth, exposingthe surface liquid to atmosphericpressure, the difference inpressure raises the liquid.

B. 1 pound pressureequals 2.31 feet head.

C. Atmospheric pressureof 14.7 x 2.31 = 33.9ft.head, which is themaximum possible liftat sea level.

NOTE: You lose approxi-mately one foot ofsuction lift per 1000 ft.

of elevation.Example: Denver, CO isapproximately 5000 ft.above sea level. The totalsuction lift would only be28.9 ft. not 33.9 ft. like atsea level.

VacuumGauge

22.6'VERTICAL LIFTPLUS FRICTION

A.20

A reading of 20" on a vacuumgauge placed on a suction sideof the pump would tell youthat you had a vacuum or

suction lift of 22.6 ft.20" x 1.13' = 22.6 ft.

14.7 lbs.1 lb.

2.31 ft.

B. C.

14.7 lbs.2.31 ft.33.9 ft.

X

G O NG !

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Summing this up:When the atmosphericpressure is 14.7 lbs. per sq.inch a perfect vacuumshould be 30 inches and thiswould lift water by suctionto a height of 33.9 ft.Most shallow well or suction

pumps are capable ofdeveloping a near perfectvacuum, and at sea levelthey can lift water aboutthirty feet. However, suctionlifts of more than 25 ft. atsea level are not recom-mended. Shallow well jetpumps deliver inadequatecapacity on lifts over 25 ft.Suction conditions, or totalsuction lift must include allresistances to the flow of thewater through the suctionpipe up to the pump. Heightor vertical lift is one resis-tance. Friction between thewater and the pipe walls isthe other resistance.Friction LossWhen water flows throughpipe, the inner wall of thepipe resists the flow of thewater. This resistance iscalled pipe friction.

Pipe friction means extrawork for the pump orsystem and presents a totalloss. Therefore, it is desirableto keep friction loss as low asis practicable in order to

waste the least possibleamount of work. Keep inmind that all work beingdone on the suction sideof the pump is actuallyperformed by the pressureof atmosphere. Since incommon practice weconsider this pressure issufficient to overcome only25 ft., the 25 ft. must alwaysinclude any losses due tofriction.

We dont have to be tooconcerned with how or whyfriction loss is incurred, but itis essential that we accept itas occurring always whenwater flows through pipes. Itis, also, most essential thatwe understand how it ismeasured.In our discussion of suctionlift, atmospheric pressureand the height this pressurewill raise water, we estab-lished the fact that 14.7 lb.

pressure will raise water to aheight of 33.9 ft. Althoughthere is no relation betweenatmospheric pressure andfriction loss, the relationbetween pounds pressureand feet elevation or headas we call it, is the samewhether the pressure iscoming from atmosphere orany other source. So, asstated before, 14.7 lbs.pressure from any sourcewill raise water 33.9 ft. andthis gives us the conversionfactor to change our termsfrom pressure to feet or thereverse of this. Therefore,1 lb. of pressure is alwaysequal to 2.31 ft. (33.9divided by 14.7 equals 2.31).Now getting back to friction

loss, the amount of this lossincreases as the quantity ofwater flowing through agiven size pipe is increased.There are formulas to

PUMPING LEVELOF WATER

23 ft.

STATIC LEVEL OF WATER

TOTAL LENGTH OF SUCTION PIPE IS 100 CAPACTIY OF PUMP IS7 GALLONS PER MINUTE

VERTICAL LIFT (ELEVATION) = 23' . . . . . . . . . 23'

FRICTION OF 7 GPMIN 100 FT. OF PIPE 1" = 3.56' 1 1 4" = .93'

TOTAL SUCTION LIFT = 26.56' . . . . . . . . . 24'

OBVIOUSLY 11 4" PIPE MUST BE USED.

25 ft.

75 ft.

Friction Loss Increaseswhen Capacity Increases

orPipe Length Increases

determine the amount offlow and any pipe size. Butwe dont have to be con-cerned with this, since it hasall been carefully calculatedand set up in the frictionloss table as shown below.Example: The example atthe top of the page showsthat using the correct sizepipe will reduce friction loss.On some jobs, a smallerpump with larger pipe willdo the same work (flow) asa larger pump with smallerpipe. Larger pipe is notmuch more expensive butlarger pumps are. Largerpumps also use moreenergy. Using the correctpipe size saves money in thelong run. Calculating friction

loss is especially important ifyou are not sure of the welldrawdown. It is a very goodrule of thumb to always usea suction pipe that is thesame size or larger than thepump suction.Friction of Water per Each 100 Feet of New Steel Pipe

GPM GPH3 8" Pipe 1 2" Pipe 3 4" Pipe 1" Pipe 1 1 4" Pipe 1 1 2" Pipe 2" Pipe 2 1 2" Pipe 3" Pipe 4" Pipe

Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs.1 60 4.30 1.86 1.86 .81 0.26 0.112 120 15.00 6.49 4.78 2 .07 1.21 0.52 0.38 0.163 180 31.80 13.77 10.00 4.33 2.50 1.08 0.77 0.334 240 54.90 23.77 17.10 7.40 4.21 1.82 1.30 0.56 0.34 0.155 300 83.50 36.45 25.80 11.17 6.32 2.74 1.93 0.84 0.51 0.22 0.24 0.106 360 36.50 15.80 8.87 3 .84 2 .68 1 .16 0.70 0.30 0.33 0 .14 0 .10 0 .047 420 48.70 21.08 11.80 5.11 3 .56 1 .54 0.93 0.40 0.44 0 .19 0 .13 0 .06

8 480 62.70 27.14 15.00 6.49 4 .54 1 .97 1.18 0.51 0.56 0 .24 0 .17 0 .079 540 18.80 8.14 5.65 2.45 1.46 0.63 0.69 0.30 0.21 0.0910 600 23.00 9.96 6.86 2.97 1.77 0.77 0.83 0.36 0.25 0.11 0.11 0.05 0.04 0.0212 720 32.60 14.11 9.62 4.16 2.48 1.07 1.16 0.50 0.34 0.15 0.15 0.06 0.05 0.0215 900 49.70 21.52 14.70 6.36 3.74 1 .62 1.75 0.76 0.52 0.23 0.22 0.10 0.08 0.0320 1200 86.10 37.27 25.10 10.87 6.34 2 .74 2.94 1.27 0.87 0.38 0.36 0.16 0.13 0.0625 1500 38.60 16.71 9.65 4.18 4.48 1.94 1.30 0.56 0.54 0.23 0.19 0.0830 1800 54.60 23.64 13.60 5.89 6.26 2.71 1.82 0.79 0.75 0.32 0.26 0.1135 2100 73.40 31.77 18.20 7.88 8.37 3.62 2.42 1.05 1.00 0.43 0.35 0.1540 2400 95.00 41.13 23.50 10.17 10.79 4.67 3.10 1.34 1.28 0.55 0.44 0.1945 2700 30.70 13.29 13.45 5.82 3.85 1.67 1.60 0.69 0.55 0.2450 3000 36.00 15.58 16.40 7.10 4.67 2.02 1.94 0.84 0.66 0.29 .18 .0870 4200 68.80 29.78 31.30 13.55 8.86 3.84 3.63 1.57 1.22 0.53 .35 .15100 6000 62.20 26.93 17.40 7.53 7.11 3.08 2.39 1.03 .63 .27150 9000 38.00 16.45 15.40 6.67 5.14 2.23 1.32 .57200 12000 66.30 28.70 26.70 11.56 8.90 3.85 2.27 .98250 15000 90.70 39.26 42.80 18.53 14.10 6.10 3.60 1.56300 18000 58.50 25.32 19.20 8.31 4.89 2.12350 21000 79.20 34.29 26.90 11.65 6.72 2.91

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3 DischargeConditions

What are the conditionsunder which the watersystem must discharge itscapacity?The capacity of the pumphas already been estab-lished so we are nowconcerned only with the

pressure required of thesystem.It seems that the pressureand its use in a domesticwater system are generallymisunderstood, so perhapssome explanation is inorder. Quite often it isstated that a particularpump is delivering suffi-cient capacity but fails todevelop adequate pressure.In most cases this is amisstatement and theopposite condition is true.This complaint is generallymade when a particularsystem fails to providesufficient flow throughseveral outlets at the sametime. This is caused in mostcases by the demand inrate of flow being greaterthan the capacity of thesystem. If the system hassufficient capacity to supplythe maximum number ofoutlets which are likely tobe used at the same time,our only concern withpressure is that we havesufficient pressure toovercome the resistanceto flow which will beencountered. If you haveany doubts about this,consider your answer tothis question:

Would you rather have ata faucet one gallon perminute at a hundredpounds pressure or tengallons per minute at tenpounds pressure? Whichwill fill a tub quicker?

Now as to the resistance toflow which will be encoun-tered, there are threecauses. These are (1) theresistance by the outletitself such as a partiallyrusted shower head, (2)friction loss in pipe lines,

and (3) that resistance dueto difference in elevations.Actually none of these willhave to be computed inmost applications becauseusually the pump isinstalled at the house, andthe standard pressurerange of the system issufficient to overcomethese resistances anddeliver its capacity to thevarious outlets. An examplein which these computa-tions must be made iswhen the pump or systemis located at considerabledistance from the point ofuse and on a lowerelevation.In such a case the differ-ence in elevation must bedetermined (1 lb. Pressureis necessary to overcomeeach 2.3 ft. elevation); the

friction loss in feetcalculated and changed topounds pressure (again thesame relation, 1 lb.Pressure equals 2.3 ft. orthis can be read directlyfrom the table in lbs.); theservice pressure or pressurerequired at the faucet mustbe decided; the total ofthese three will be thedischarge conditions oroperating pressure requiredof the pump.

ExampleService pressure desired

30 lbs. min.................... 30 lbs.

Elevation 23 ft.1 lb. = 2.3 ft.23 ft. / 2.3 ft. = 10 lbs. .. 10 lbs.

Friction:Pump capacity is 7 gpmThis flow through 200 ft.of 1" pipe gives a frictionloss of 3.06 lbs. .................. 3 lbs.

43 lbs.Pressure switch setting at thepump would be (43-63 lbs.)

This means when the pressureswitch cuts the pump on at about43 lbs. Tank pressure, the pressureat the house will be 30 lbs. Whenthe water is flowing at a rate of7 gallons per minute.

PSI PRESSURE

1 GALLONPER MINUTE

PSI

100 10

10 GALLONSPER MINUTE

FRICTION LOSS?

ELEVATION?

UNUSUAL CONDITION

NO PROBLEM

AVERAGE CONDITIONS

30PSI

200'1" PIPE

23'ELEVATION

10


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Types of PumpsJet SystemsThe first question with Jet Pumps is what is the suctionchamber and how is the vacuum created.The Jet Assembly itself forms the suction chamber andthe vacuum is created by the very high velocity of a

stream of water passing through the jet. Basically, the jetassembly is composed of two parts. First, a nozzle whichproduces the high velocity stream of water. This highvelocity stream of water is injected through a smallcompartment which is the suction chamber, therebycausing the vacuum. Obviously, the suction pipe isconnected to this compartment or suction chamber. Thevacuum caused by the jet permits the greater pressure ofatmosphere on the surface of a body of water to forcewater into the suction chamber.The second basic part of the Jet Assembly is the venturitube. It is installed in the discharge of the suction

chamber. Its function is to convert the velocity of thewater into pressure. This is accomplished by the shape ofits water passage. Perhaps you can best visualize this bythinking of a nozzle in reverse. The nozzle speeds up theflow of the drive water converting pressure into velocityand when it has passed through the suction chamber,the venturi slows it down again converting the velocityback into pressure.Drive water is that water which is piped under pres-sure to the jet assembly or suction chamber. The dis-charge from the suction chamber or jet assembly iscomposed of both the drive water and that waterpumped from the well. The total amount pumped fromthe well can be used as discharge from the system and isthe output or capacity.

Shallow Well Jet PumpFrom the foregoing discussion it is obvious that theoperation of the Jet system is dependent on the com-bined functions of both the Jet Assembly or suctionchamber and the centrifugal pump. Also, that these twomain components of the system are entirely separateand their locations with respect to each other is a matterof design.

In shallow well jet pumps the jet assembly is built intothe pump casing as in the Goulds Pumps J5S. Or, the jetassembly, shallow well adapters, can be bolted to thecentrifugal pump. In either case there is only one pipe

extending into the well . . . the suction pipe.Deep Well Jet PumpThe only basic or fundamental difference between ShallowWell and Deep Well Jet Pumps is the location of the JetAssembly. It must always be located in such a position thatthe total suction lift between it and the pumping level ofthe water to be pumped does not exceed that which canbe overcome by the pressure of atmosphere. This, ofcourse, means that when this pumping level is at a distancelower than the ground level which cannot be overcome byatmospheric pressure, the Jet Assembly must be located atleast five feet below the low water in the well.

We must have a closed compartment in which to install thenozzle and the venturi and to form the suction chamber.This part is called the jet body. Its shape is such that it will fitinto the casing of a drilled well and the pipe connectionsare located for accessibility. There are two on the top side,one for connection to the pressure pipe which supplies thedrive water, the other for connection to the suction pipewhich returns both the drive water and the water pumpedfrom the well. For this reason, this connection is one pipesize larger than that for the pressure pipe. Water from thewell enters through a third opening which is on the bottomside of the jet body.The last accessory for the Jet System is the pressure controlvalve. It is a valve installed in the discharge piping from thecentrifugal pump between the pump and the tank; in thepump when the pump is mounted on a tank. Used only indeep well systems, its purpose it to assure a minimumoperating pressure for the jet.

11

Install CheckValve HereOrFoot Valveat End ofSuction Pipe

Nozzle

Venturi

J e t P u m p

Foot Valve

Twin PipeDeep WellJet Assembly

Nozzle

Venturi

SuctionPipe Pressure Pipe

PressureControlValve (AV22)


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Submersible PumpSubmersible pumps are so named because the whole unit,pump and motor is designed to be operated under water.This means the pump does not have to be primed. Onceinstalled and turned on, water flows up the pipe.

The pump end is a multistage (many impellers) centrifugalpump, close coupled to a submersible electric motor. All ofthe impellers of the multistage submersible rotate in thesame direction by a single shaft. Each impeller sits in a bowland the flow from the impeller is directed to the nextimpeller through a diffuser. These three parts (bowl, impellerand diffuser) are known as a stage.

The capacity of a multistage centrifugal pump (submersible)is largely determined by the width of the impeller anddiffuser, regardless of the number of stages. The pressureis determined by the diameter of the impeller, thespeed at which it rotates and the number ofimpellers. The diameter is limited to the size ofwells drilled. Most submersibles are designed tofit in four or six inch wells (or larger).A 1 2 HP pump with seven impellers (designed forcapacity) would deliver more water at 80' than a1 2 HP pump with 15 impellers (designed forpressure) but the latter pump would be able toraise water from a greater depth.Well water enters the unit through screenedopenings at the middle of the unit between thepump and motor. There is only one pipe connec-tion which is at the top of the pump. This is thedischarge pipe. A check valve is located at the top

of the unit to prevent water from the systemdraining back when the pump isnt running.

Submersible pumps are so much more efficient than jetpumps and the installation so much simpler that a submers-ible pump should be considered first for all pump applica-tions where the physical dimensions of the source of the

water will accommodate the unit in a submerged position.Example: 60 ft. pumping level;30-50 lbs. Pressure.1 2 HP submersible ...................................... .......... 11 gpm1 2 HP jet system........................................ ............. 6 gpm

Centrifugal PumpThe centrifugal pump does two things. It circulates thedrive water at the pressure required to produce thenecessary velocity in the Jet. It also boosts the pressureof that water being pumped from the well delivering it

through the discharge of the system at a satisfactoryservice pressure. Since the one return pipe from the jetassembly contains both these quantities of water, thisreturn pipe is connected direct to the suction opening ofthe centrifugal pump. The action of the centrifugalpump can be thought of as that of a paddlewheel. Theimpeller is a multi-vane (or blade) wheel and its design issuch that its size, shape and speed impart sufficientenergy to the water in the system to circulate it at thedesired rate.As the water is discharged from the centrifugal pump, itis divided. The drive water, or that amount required tooperate the Jet is piped directly to the Jet through thepressure pipe. It is continuously recirculated so long asthe centrifugal pump is running. That amount pumpedfrom the well is discharged from the centrifugal pumpdirectly into the tank and is the capacity of the system.

Centrifugal Pump Characteristics Impeller attached to a Motor/Driver Impeller draws the HP off the Motor/Driver Flexible machine; capable of a

range of performances atgood efficiencies

Will overload motor (pumpsmax. capacity)

Limited Suction Lift capability(15-25') Impeller makes own pressure

(PSI) Adds its pressure to any incoming pressure Poor air-handling capability (Cavitation, loss of suction/

prime, and air-binding)

12

Diffuser

Impeller

Bowl

Shaft

Diameter of Impeller

Affects PressureWidth of Impeller VanesAffects Capacity


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Accessories

When applying a pump to any specific problem pertain-ing to domestic water supply, our objective in practicallyevery case should be to provide automatic runningwater under pressure a water service comparable tothat which might be expected from connection to a citywater main. But, a pump alone can hardly perform theseveral necessary functions. Certain other accessories arenecessary, and the combination of them all forms whatwe call a water system.MotorsThe first accessory is the drive medium which on practi-cally all water systems of today is an electric motor. Youshould remember that some of our pumps, in particularthe jet pumps in large motor sizes and submersiblepumps, are furnished with motors of current characteris-tics as specified. Therefore, when ordering these, wemust be advised the electrical characteristics.

Pressure SwitchThe next accessory required is a pressure switch to startand stop the motor automatically at a predeterminedpressure. A tube connects the switch to some point inthe system on the discharge side of the pump. Thepressure in the system then acts directly on a diaphragmin the switch which in turn actuates the contacts in theswitch.

Pressure TanksThe rate at which water can be used in a home, school,motel, or any other place can be as little as one gallon aminute (60 gallons per hour) (brushing teeth or rinsinghands). Or the maximum can be hundreds or thousandsof gallons per hour depending on the number of waterusing fixtures and, or appliances in use at the sametime.A pump capable of delivering a capacity equal to themaximum demand cannot necessarily be throttled tothe minimum demand.The main purposes of a pressure tank are to pressurizethe system to make it operate automatically and toproperly cycle the pump to properly cool the motor. Thisprevents excessive short cycling (too rapid starting andstopping). The pump capacity and size motor should

always be considered. The larger a motor is in horse-power the more starting power required; therefore, theless frequently it should be started.It is good practice to size the tank to require the pumpto run at least one minute per cycle when using frac-tional horsepower motors and two to three minutes forlarger motors.

There are three basic types of tanks in use today.Conventional or Galvanized TypeRequires an air volume control deviceto keep proper amount of air cushionin the tank.

Floating Disc TypeDisc helps in preventing water fromabsorbing air but is not absolute. Itrequires periodic replenishment of airthrough air valve.

Sealed Diaphragm Type

Water and air are permanentlyseparated by sealed diaphragm;therefore, the amount of air neverchanges. The amount of draw-offalso never changes.

Relief ValveAs a precaution or protection against the possibility ofthe switch becoming stuck at some time allowing thepump to continue running after sufficient pressure hasbeen obtained, a relief valve is necessary with all systemscapable of developing pressures in excess of the work-ing limits of the tank. A relief valve is a spring controlledvalve located somewhere close to or in the pump on thedischarge side, or on the tank. The tension of the springis so adjusted that it will permit the valve to open andallow the water to escape if the pressure in the systemexceeds by more than about 10 lbs. That at which thepressure switch is set to cut off the current to the motor.

Foot ValveA foot valve is a combination check valve and strainer.

AIR

WATER

AIR VOLUMECONTROL

FLOATINGDISC

AIR

WATER

AIR

WATER

AIR VALVEDIAPHRAGM

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Summary

Now lets summarizebriefly the points wevecovered. We have shownthat in a water systemapplication, there are threefactors to consider:1. Water Needed or Deter-

mination of Capacity2. Suction Conditions, and3. Discharge Conditions.We have concluded thatcapacity required is deter-mined by the maximumnumber of outlets whichwill be in continuous useat the same time with aminimum flow of threegallons per minute peroutlet.We have shown that all jetpumps, whether shallowwell or deep well, have awater end in which there isa suction chamber; that thesuction chamber is actuallya closed container in whicha partial vacuum is created.This allows atmosphericpressure to force in the

water. The suction chambermust be located withinabout 25 feet verticaldistance above the pump-ing level of the water.The main differencebetween shallow well anddeep well pumps is that inthe former the water end isbuilt onto the power end.The water end of deep well

jet pumps is a separatepart. It is installed in thewater and is used to pumpwater from levels below a25 feet depth. We haveshown that a submersibleshould be used whensource will allow. Since thesubmersible is submerged

in water only dischargeconditions apply. Weveestablished three distinctforms of resistance to flowencountered as DischargeConditions and shown thatthey must be consideredbut computed only inspecial cases. Also, that the

pump is only part of thesystem necessary toprovide an automaticservice. Other accessoriesare necessary and weveestablished the need andfunction of each of theseaccessories.We have mentioned 3 GPMas a minimum acceptableflow rate per outlet. But alarger flow rate is moredesirable and the followingtable should be used as anaverage supply requiredwhen the source of supplywill allow it.We would like to leave youwith one thought. That is,capacity and pressure are

inversely related. When onegoes up, the other goesdown. Always check therating chart or curve of apump to make sure if youraise the pressure you willstill receive the neededsupply of water at youroutlets.

Seven Minute Peak Demand Period Usage

Outlets Flow Rate Total Usage Bathrooms In HomeGPM Gallons 1 1 1 2 2-2 1 2 3-4

Shower or Bath Tub 5 35 35 35 53 70Lavatory 4 2 2 4 6 8Toilet 4 5 5 10 15 20Kitchen Sink 5 3 3 3 3 3Automatic Washer 5 35 18 18 18Dishwasher 2 14 3 3Normal seven minute*peak demand (gallons) 45 70 98 122Minimum sized pump required to meet peak 7 GPM 10 GPM 14 GPM 17 GPMDemand without supplemental supply (420) (600) (840) (1020)

Note: Values given are average and do not include higher or lower extremes. * Peak demand can occurseveral times during morning and evening hours.

Additional Requirements: Farm, irrigation and sprinkling requirements are not shown. These values mustbe added to the peak demand figures if usage will occur during normal demand periods.

Performance Rating inGallons per Minute

Pump Discharge PressureTotal Max.

Suction 20 PSI 30 PSI Shut-OffLift in Lbs.

5 feet 8 6 51 lbs.GPM GPM

Using the rating chartbelow, we would begetting 8 GPM from thepump at 20 lbs. pressure.If we were trying tosupply two outlets atonce, this would give usapproximately 4 GPM ateach one. If we increasethe pressure to 30 lbs.pressure, we only get6 GPM which will give usapproximately 3 GPM ateach outlet. By raising thepressure we have reducedthe amount of water ateach outlet by approxi-mately 25%.Always check the pumpperformance rating

before making a change.

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15/20

1. What well conditions might possibly limit thecapacity of the pump?

2. How does the diameter of a cased deep well andpumping level of the water affect the capacity?

3. If there are no limiting factors, how is capacitydetermined?

4. What is suction?

5. What is atmospheric pressure?

6. How much is the pressure due to atmosphere?

7. What is maximum theoretical suction lift?

8. How does friction loss affect suction conditions?

9. When and why do we use a deep well jet pump?

Questions & Answers

Rate of flow from the source of supply, the diameter ofa cased deep well and the pumping level of the water ina cased deep well.

Limits the size pumping equipment which canbe used.

Maximum number of outlets or faucets likely to be inuse at the same time.

A partial vacuum created in suction chamber of pumpobtained by removing pressure due to atmosphere,thereby allowing greater pressure outside to forcesomething (air, gas, water) into the container.

The atmosphere surrounding the earth presses againstthe earth and all objects on it, producing what we callatmospheric pressure.

This pressure varies with elevation or altitude. It isgreatest at sea level (14.7 lbs. Per sq. in.) and graduallydecreases as elevation above sea level is increased. Atthe rate of approximately 1 foot per 1000 feet of

elevation.Since suction lift is actually that height to whichatmospheric pressure will force water into a vacuum,theoretically we can use the maximum amount of thispressure 14.7 lbs. per sq. in. at sea level which will raisewater 33.9 ft. From this, we obtain the conversion factorof 1 lb. per sq. in. of pressure equals 2.31 ft. head.

The resistance of the suction pipe walls to the flow ofwater uses up part of the work which can be done byatmospheric pressure. Therefore, the amount of loss dueto friction in the suction pipe must be added to thevertical elevation which must be overcome and the totalof the two must not exceed 25 feet sea level. This 25feet must be reduced 1 foot for every 1,000 feet eleva-tion above sea level which corrects for a lessenedatmospheric pressure with increased elevation.

When the water level is more than 25 feet below thepump because this is the maximum practical suctionlift which can be obtained with a shallow well pump atsea level.

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10. What do we mean by water system?

11. What is the purpose of a foot valve?

12. Name the two basic parts of a Jet Assembly.

13. What is the function of the nozzle?

14. What is the purpose of the venturi?

15. What do we mean by drive water?

16. What is the source of the drive water?

17. What is the purpose of the centrifugal pump?

18. Where is the Jet Assembly usually located in aShallow Well Jet System?

19. What is the principal factor which determines if ashallow well jet system can be used?

20. When is a deep well jet system used?

21. Can a foot valve be omitted from a Deep Well JetSystem? Why?

22. What is the function of a check valve in the top ofa submersible pump?

23. A submersible pump is made up of two basic parts.What are they?

24. Why did the name submersible pump come intobeing?

A pump with all necessary accessories, fittings, etc.,necessary for its completely automatic operation.

It is used on the end of a suction pipe to prevent thewater in the system from running back into the sourceof supply when the pump isnt operating.

Nozzle and Venturi.

The nozzle converts the pressure of the drive water intovelocity. The velocity thus created causes a vacuum inthe Jet Assembly or suction chamber.

The venturi converts the velocity from the nozzle backinto pressure.

That water which is supplied under pressure to drive the jet.

The drive water is continuously recirculated in a closedsystem.

The centrifugal pump provides the energy to circulatethe drive water. It also boosts the pressure of the

discharged capacity.Bolted to the casing of the centrifugal pump.

A maximum suction lift of 25' at sea level.

When the total suction lift exceeds 25 '.

No, because there are no valves in the Jet Assembly andthe foot valve is necessary to hold water in the systemwhen it is primed. Also, when the centrifugal pump isntrunning, the foot valve prevents the water from runningback into the well.

To hold the pressure in the line when the pump isntrunning.

Pump end and motor.

Because the whole unit, pump and motor, is designed tobe operated under water.

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25. A submersible pump can be installed in a 2" well?

26. A stage in a submersible pump is made up of threeparts. What are they?

27. A submersible pump has only one pipe connection?

28. What are two reasons we should always considerusing a submersible first?

29. The amount of pressure a pump is capable ofmaking is controlled by what?

30. The width of an impeller and guide vane controlwhat?

No, they required a 4" well or larger for most domesticuse. Larger pumps with larger capacities require 6" wellsor larger.

Impeller, diffuser and bowl.

True, for the discharge pipe.

It will pump more water at higher pressure with lesshorsepower. Easier installation.

The diameter of the impeller.

The amount of water or capacity the pump is capable ofpumping.

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18/20

Problems

Friction of Water PER EACH 100 FEET of New Steel Pipe

GPM GPH3 8" Pipe 1 2" Pipe 3 4" Pipe 1" Pipe 1 1 4" Pipe 1 1 2" Pipe 2" Pipe 2 1 2" Pipe 3" Pipe 4" Pipe

Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs. Ft. Lbs.1 60 4.30 1.86 1.86 .81 0.26 0.112 120 15.00 6.49 4.78 2.07 1.21 0.52 0.38 0.163 180 31.80 13.77 10.00 4.33 2.50 1.08 0.77 0.334 240 54.90 23.77 17.10 7.40 4.21 1.82 1.30 0.56 0.34 0.155 300 83.50 36.45 25.80 11.17 6.32 2.74 1.93 0.84 0.51 0.22 0.24 0.10

6 360 36.50 15.80 8.87 3.84 2.68 1.16 0.70 0.30 0.33 0.14 0.10 0.047 420 48.70 21.08 11.80 5.11 3.56 1.54 0.93 0.40 0.44 0.19 0.13 0.068 480 62.70 27.14 15.00 6.49 4.54 1.97 1.18 0.51 0.56 0.24 0.17 0.079 540 18.80 8.14 5.65 2.45 1.46 0.63 0.69 0.30 0.21 0.09

10 600 23.00 9.96 6.86 2.97 1.77 0.77 0.83 0.36 0.25 0.11 0.11 0.05 0.04 0.0212 720 32.60 14.11 9.62 4.16 2.48 1.07 1.16 0.50 0.34 0.15 0.15 0.06 0.05 0.0215 900 49.70 21.52 14.70 6.36 3.74 1.62 1.75 0.76 0.52 0.23 0.22 0.10 0.08 0.0320 1200 86.10 37.27 25.10 10.87 6.34 2.74 2.94 1.27 0.87 0.38 0.36 0.16 0.13 0.0625 1500 38.60 16.71 9.65 4.18 4.48 1.94 1.30 0.56 0.54 0.23 0.19 0.0830 1800 54.60 23.64 13.60 5.89 6.26 2.71 1.82 0.79 0.75 0.32 0.26 0.1135 2100 73.40 31.77 18.20 7.88 8.37 3.62 2.42 1.05 1.00 0.43 0.35 0.1540 2400 95.00 41.13 23.50 10.17 10.79 4.67 3.10 1.34 1.28 0.55 0.44 0.1945 2700 30.70 13.29 13.45 5.82 3.85 1.67 1.60 0.69 0.55 0.2450 3000 36.00 15.58 16.40 7.10 4.67 2.02 1.94 0.84 0.66 0.29 .18 .08

70 4200 68.80 29.78 31.30 13.55 8.86 3.84 3.63 1.57 1.22 0.53 .35 .15100 6000 62.20 26.93 17.40 7.53 7.11 3.08 2.39 1.03 .63 .27150 9000 38.00 16.45 15.40 6.67 5.14 2.23 1.32 .57200 12000 66.30 28.70 26.70 11.56 8.90 3.85 2.27 .98250 15000 90.70 39.26 42.80 18.53 14.10 6.10 3.60 1.56300 18000 58.50 25.32 19.20 8.31 4.89 2.12350 21000 79.20 34.29 26.90 11.65 6.72 2.91

From the table, give the friction loss in ft. for the following conditions:3 4" 11 4" 2"

1. 360 GPH ................................. a b c2. 600 GPH ................................. a b c

3 4" 11 4" 2"3. 420 GPH ................................. a b c4. 600 GPH ................................. a b c

1 2" 1" 11 2"5. 240 GPH ................................. a b c6. 480 GPH ................................. a b c

3 4" 1" 11 4"7. 360 GPH ................................. a b c8. 600 GPH ................................. a b c

100 Feet of Pipe

50 Feet of Pipe

150 Feet of Pipe

80 Feet of Pipe

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19/20

Problems (continued)

1.

Pump Capacity 6 GPM

Elevation: 23 ft.

Friction Loss: 4 lbs.

Operating Pressure: 20-40 lbs.

a. What is the Service Pressure?

Pump Capacity 6 GPM

a. What is friction loss?

b. What is total lift?

Total Equivalent Length of SuctionPipe from Pump Down into Well.

30 ft. 3 4" Pipe

15 ft. Vertical Lift

Standing level of water

Pumping level of water

2.

Pump Capacity 10 GPM

a. What size suction pipe is required to keep totallift within 25 feet?

b. What is friction loss?

c. What is total lift?

Total Equivalent Length of SuctionPipe from Pump Down into Well.

140 ft. Pipe

18 ft. Vertical Lift

Standing level of water

Pumping level of water

3.

Service Pressure

Friction

Elevation

Pump and TankWell House

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20/20

ServicePressure

FrictionElevation

Pump and TankWellHouse

4.

Pump Capacity 6 GPM

Elevation: 23 ft.

Operating Pressure: 20-40 lbs.

200 ft. of 3 4" Discharge Pipe

a. How much is friction loss?

b. What is the Service Pressure?

c. What change would you make in this systemand what would the result be?

Pump Capacity 10 GPM

Elevation: 80 ft.

Service Pressure Required: 20-40 lbs.

Length of Discharge Pipe: 300 ft.

a. What size pipe to use?

b. How much is friction loss?

c. What will the operating pressure of the pumpbe?

d. How many continuous use outlets operating atthe same time will this capacity supply?

Pump Capacity is 8 GPM.Service Pressure Required at Tank in Basementis 30 lbs.

a. What is the total length of pipe to be consideredfor friction loss? Ft.

b. What is the friction loss in feet? Ft.

c. What is the total feet the pump will have toovercome to get water to the tank? Ft.

ServicePressure

FrictionElevation

Pump and TankWellHouse

5.

PUMPING LEVEL

PUMP SETTING

50' ELEVATION

120'

20'

3 0 0 ' O

F 1 " P

I P E

PRESSURESWITCH

Problems (continued)

Documents

Residential Pumps