












                        WELL PUMP SIZER
                       INSTRUCTION MANUAL



















                          Sim J. Blake
                            25 JUN 95













        COMPUTER PUMP MODELLING PROGRAM FOR WATER WELLS





                      PROGRAM DESCRIPTION

The Well Pump Sizer allows a user to size a pump for a water well
or booster application.  Input consists of:  H vs. Q values for a
pump  curve,  well  specific capacity static water  level,  motor
speed, number of stages and system outlet pressure or flow  rate.
Results  returned  are:  flow rate (or outlet pressure,  if  flow
rate is specified), total dynamic head, hydraulic horsepower  and
pumping water level.  Motor speed, number of stages, pressure and
flow may be quickly and easily varied, and the operating point on
the  curve  is graphically shown.   The program requires  an  IBM
compatible  PC; the program will run without a math  coprocessor,
but  a  coprocessor is used if present and is highly recommended.
A  graphics  adaptor is not necessary, but a VGA or EGA  graphics
capability  is  required to display pump  curves  and  take  full
advantage of the program.


                          INTRODUCTION

An important aspect of obtaining the optimum efficiency out of  a
water  well  is  the  sizing of the pump and  motor  combination.
Centrifugal  pumps,  either alone or  in  a  stacked  multi-stage
arrangement,  are  the type of pumps which are normally  used  in
water well & booster installations; the purpose of the Well  Pump
Sizer  is  to  aid in the selection of an appropriate centrifugal
pump to use in a water well.

The normal process for selecting a pump consists of taking a pump
performance  curve  of head vs. discharge,  a  known  or  assumed
system  discharge pressure, a known well specific yield  in  flow
per  foot  of  drawdown and plotting an operating  point  on  the
curve.   The  efficiency  is  then determined  by  comparing  the
operating point to the pump efficiency curve.  Plotting  such  an
operating  point is an iterative process if a constant  discharge
pressure is to be maintained.  Normally, pump curves are supplied
for  a  small range of stages, and occasionally for  a  range  of
speeds; if operation over different ranges of speeds or number of
stages than provided by the pump data is desired, the curves must
be  rescaled and the process must be repeated until either a good
combination  of stages, discharge, outlet pressure,  motor  speed
and  efficiency is found, or the pump is found to be  unsuitable.
Even  if  one does not desire to rescale pump curves, the process
can  get  quite  lengthy if a lot of pumps or  a  wide  range  of
conditions are to be looked at.

The Well Pump Sizer provides an alternative to the hand graphical
methods  used  to determine pump suitability and ideal  operating
conditions.  The program allows the user to play "what if" with a
pump  curve  and  instantly determine pump  operating  points  by
varying such parameters as number of stages, motor speed,  outlet
pressure,  flow rate, as well as determine the optimum  operating
point   for  the  condition  of  maximum  efficiency.   An  ideal
combination  of  pump operating parameters may  then  be  quickly
arrived at.















                       THEORETICAL BASIS


The  program is based on the following assumptions, and  must  be
used  within  certain limitations to ensure accurate results  and
ease  of  use.   In  any case, it would be a prudent  measure  to
verify  by  hand any result of the program to be used for  design
purposes.

A.  Well Modelling

     The  well  is  assumed to be pumping water,  with  a  linear
     specific  capacity  in GPM per foot of  drawdown  below  the
     static water level, and a steady state condition is assumed;
     i.e. drawdown does not change with time.  Static water level
     is  the distance in feet below ground level where the  water
     lies in a non-pumping situation; pumping water level is  the
     static  water  level plus drawdown, which is the  flow  rate
     divided by the specific capacity.

B.  Pump Curve Modelling

     The  pump  curve input consists of from four to twenty  head
     vs. flow points where head is in feet of water, and flow  is
     in  GPM.  A cubic equation is then fitted to the points with
     H  being a function of Q; this equation is formed each  time
     an  operating  point is computed and is scaled according  to
     the following centrifugal pump affinity laws for changes  in
     stages or motor speed:

          H2 = H1 x (#STAGES2/#STAGES1) x (RPM2/RPM1)2

                  and   Q2 = Q1 x (RPM2/RPM1)

     The  point of maximum efficiency stays in the same  relative
     position  according to these laws.  The  affinity  laws  are
     valid and are good estimations of actual performance as long
     as  the changes are not extreme.  Variations of two or three
     stages  and speed changes of up to about fifty percent  have
     been observed to agree quite well with actual pump curves.

C.  Calculation of Total Dynamic Head

     The  total dynamic head represents the total head  that  the
     pump  must  work against; it equals the pumping water  level
     plus  the outlet pressure head plus the kinetic head  V2/2G.
     This  program ignores the kinetic term which represents  the
     energy  needed to accelerate the water from a standstill  to
     the  velocity in the pipe.  Even in extreme cases, this term
     usually accounts for less than 1 psi; the great majority  of
     the  energy imparted to the fluid by the pump is present  in
     the  form  of  static  head.  In practice,  pipe  sizes  are
     normally chosen so that velocities are below ten fps  (which
     is  a  kinetic head of 1.5 ft) in the interest of minimizing
     frictional losses.






D.  Treatment of Frictional Losses

     Frictional losses are not taken into account in the program;
     piping  runs  from the well to the distribution  system  are
     relatively  short  and  insignificant.   Beginning  at   the
     distribution system, the operating pressure is dependent  on
     system dynamic effects which can only be predicted by a full
     scale hydraulic model of the distribution system.  A well or
     water system booster pump is faced with a situation where it
     must  pump into a fairly constant outlet pressure  which  is
     not  dependent  on the flow rate of the pump.   This  is  in
     contrast  to a process plant situation, where the length  of
     the  pipe  runs are much shorter and the operating point  of
     the  pump is dependent on velocity induced frictional losses
     in the pipes.  For this reason, the outlet pressure does not
     vary with flow.

E.  Calculation of Flow and Outlet Pressure

     By  default,  unless the flow is varied, outlet pressure  is
     held constant and the flow calculated through variations  of
     other parameters.  Since H = f(Q), it is necessary to use  a
     numerical  equation  solving  routine  to  solve  the  cubic
     equation  for  Q;  this assumes a solution  in  between  two
     initial guesses of zero GPM and twenty five percent past the
     last  curve point entered (which is used to flag for out  of
     range  operation).  In order for the program to converge  on
     the   correct   solution,  all  heads  must  decrease   with
     increasing  flow.  The program will not accept curve  points
     entered  in violation to this rule; however, the pump  curve
     must  be  examined to ensure that the fitted curve does  not
     violate the rule.

F.  Determination of the Maximum Efficiency Point

     Efficiency   is  defined  as  power  output/  power   input;
     considering the input power of the pump to be constant,  the
     maximum  efficiency will be reached at the point of  highest
     output  power.  Hydraulic horsepower (pump output power)  is
     calculated  for  each point on the curve (in  increments  of
     1/2000th  of  the  maximum flow) and the highest  horsepower
     found and its corresponding flow rate is recorded; this flow
     rate  is  the flow at maximum efficiency.  In reality,  pump
     input  power is not constant and the efficiency is dependent
     on the relationship between input power and output power, so
     the  actual point of maximum efficiency may be slightly  off
     from that calculated by the program.









                    OPERATIONAL INSTRUCTIONS

Operation  consists of the following general  steps:   1)   Enter
pump  curve  points,  2)  Enter data specific to  the  well,   3)
Save  the data for later use,  4)  Perform the evaluation.   Data
may be entered either by the data entry options or by a file,  if
one  has  been  created; the operational steps will be  explained
below.  in all cases, selecting a menu choice is accomplished  by
either  typing  the selection number or the first letter  of  the
item.

A.  Entering Data

  1.  Program startup

     The  program name is PUMP.EXE; to start the program from the
     A  drive, type "pump" (example -  A:\> pump) at the  prompt.
     It is highly recommended that the program be installed on  a
     hard  disk.   The data files should be located in  the  same
     directory that the program has been started from in order to
     be  able to list them.  After starting the program, two menu
     choices will appear, "File operations" and "Evaluations  and
     results"; select "File operations".

  2.  File entry

     If  a  data file is present, it can be entered.  In the File
     Operations  menu,  select "Retrieve data file";  the  screen
     will display all of the files in the current directory and a
     prompt to enter a filename will appear.  If the desired data
     file is on another disk or directory, it can be selected  by
     typing  in  the  filename  prefixed  with  the  path.   Upon
     entering  the  filename, the contents of the  file  will  be
     displayed on the screen, and pressing a key will bring  back
     the File Operations menu.

  3.  Pump Curve Entry

     In  order  to  evaluate  a pump, the  pump  curve  and  well
     specific  data must be entered.  Select "Pump  curve  entry"
     and  enter the number of points; at least four are required,
     but  up  to twenty may be entered.  If a number out of  this
     range  is entered, the prompt to enter the number of  points
     will  appear  again.  After entering the number  of  points,
     prompts  will  appear to enter H and Q  values.   The  first
     point  entered  is the cutoff head, it must be  the  highest
     head,  and its corresponding flow should be zero or a  small
     value.   Each successive head must be smaller than or  equal
     to  the  previous, and each successive flow must be  greater
     than or equal to the previous; any deviation will result  in
     a  prompt to reenter the point.  Enter the number of  stages
     and  the  rpm  corresponding to the pump curve,  changes  in
     stages or rpm will use these values for scaling purposes.



1Fig. 1, Typical Pump Curves


     Points should be chosen with care; an attempt should be made
     to  enter points on the inflection points of the pump curve,
     if  present.  It is not normally necessary to use all twenty
     points available, anywhere from four to six points can do  a
     good  job if they are chosen in the right places.  Once  the
     pump curve has been entered, the "Draw pump curve" selection
     should  be chosen, if a graphics adapter is present, a  pump
     curve  will be drawn; if the curve does not match the  shape
     of  the  supplied curve, reenter the curve choosing some  of
     the  points  in  slightly  different  locations.  The  curve
     fitting  routine uses a "best fit" method to draw  a  smooth
     curve  through  the  points.  The curve is  a  third  degree
     polynomial,  which  means it can have two inflection  points
     (changes in curve direction).

  4.  Well data entry

     Select   "Well  specific  data  entry"  and  enter  specific
     capacity,  standing  water  level  and  outlet  pressure  as
     prompted.   If  the specific capacity is not known,  or  the
     application is for a booster drawing water out  of  a  tank,
     etc...,  choose a large number, such as 1,000 GPM/ft.   This
     drawdown  feature can also be used to roughly simulate  pipe
     head losses in certain applications.  If the outlet pressure
     and  the standing water level combination exceeds the cutoff
     head of the pump curve, a warning message is given.

  5.  Saving the data file

     Once  steps 4 and 5 have been completed, the data should  be
     saved.  Select "Save data file" and enter a filename in  the
     DOS   format.    A   recommended   filename   extension   is
     <filename.DAT>.

  6.  Viewing the data file

     Selecting "View data file" will display the current data  in
     memory  on  the  screen  until  a  key  is  pressed.    This
     information  is  displayed automatically  on  the  graphical
     result  screen, but this feature is useful if  graphics  are
     not supported.





B.  Evaluation of Data

In  general,  certain well design parameters are normally  given.
Outlet  pressure is normally fixed at system pressure,  typically
around  fifty  to  sixty  psi, hence  the  program  holds  outlet
pressure constant unless specifically changed, either directly or
by  specifying  a flow or performing an efficiency  optimization.
Subsequent  calculations hold the new outlet  pressure  constant.
The   general  object  is  to  pump  curve/number  of  stages/rpm
combination which will operate at a specified outlet pressure and
flow  at  maximum  efficiency.  When any of  the  parameters  are
changed,  the  present  value  is displayed  in  parentheses  and
selected as the default if <return> is pressed without entering a
value.

  1.  Calculating results

     Select   the  "Evaluation  and  results"  menu  and   choose
     "Calculate results".  If graphics is supported, a  graphical
     result  screen  will appear with the pump  curve  in  a  box
     covering  the  top left quadrant of the screen.   Two  green
     lines  converging  on  a  point on the  curve  indicate  the
     operating  point  of the pump, and a green circle  indicates
     the  calculated point of maximum efficiency.  The object  of
     the  evaluation is to end up with the corner formed  by  the
     lines within the circle, while keeping other parameters at a
     desirable  level.  White numbers at the origin of the  curve
     graph  indicate the cutoff head (Hc), and the  maximum  flow
     rate  (Qm).   Below the curve, a table of results  indicates
     the  flow rate, total dynamic head, outlet pressure, pumping
     and   standing  water  levels,  percentage  of  the  maximum
     efficiency  (not the efficiency itself), and  the  hydraulic
     horsepower.  The upper right quadrant displays the  original
     curve  points entered, and the lower right quadrant contains
     the polynomial equation for the pump curve.

  2.  Optimization for efficiency

     Select "Efficiency optimization" to set the flow rate  equal
     to   flow   at  the  calculated  maximum  efficiency,   when
     "Calculate  results"  is selected, the  result  screen  will
     indicate  the  outlet  pressure and  flow  rate  at  maximum
     efficiency,  and  the percentage of maximum efficiency  will
     indicate 100 %.  The percentage of maximum efficiency  gives
     a  relative  indication of how close to top  efficiency  the
     pump is operating; the actual efficiency at any point can be
     easily  determined by dividing the hydraulic  horsepower  by
     the  input  horsepower, if given, or from the supplied  pump
     curve.  The calculated efficiency point may be slightly  off
     of  the actual point of maximum efficiency depending on  the
     variation  of  input  to hydraulic horsepower  (the  program
     assumes a constant input horsepower), but it will be  close.
     In  any  case, data from the actual efficiency curve  should
     take precedence.





  3.  Changing number of stages

     Normally,  adding  or  subtracting  stages  is  the  way  to
     increase  or  decrease flow.  Adding a stage  increases  the
     pump's  head,  causing  it to fall back  on  the  curve  and
     operate at a higher flow rate at a constant outlet pressure.
     The  stages can be changed in increments of one by selecting
     "Stage   number  change".   If  a  "Calculate  results"   is
     performed  and  the  total head required  exceeds  the  head
     available  from the pump, a warning message indicating  that
     not  enough stages are present displays, and the  number  of
     stages   is  automatically  incremented  by  one.   Repeated
     selections  of  "Calculate results" will add a  stage  until
     enough  are  present  to  start  pumping.   If  the  message
     appears,  be sure to check on the number of stages  present.
     When  the pump curve is plotted on the result screen, it  is
     scaled  for the original data conditions; if the  number  of
     stages is reduced, it will be scaled down, but if the number
     of   stages  is  increased,  it  will  not  be  scaled   up.
     Regardless of how the displayed curve is scaled, the results
     will be correct.

  4.  Changing motor speed

     Normally,  three phase alternating current induction  motors
     are  used to drive pumps.  Unless a variable frequency drive
     unit  is  to  be used to control the motor (or  an  internal
     combustion  engine or other variable speed motor  is  used),
     speed  increments  should  be chosen  corresponding  to  the
     synchronous speeds of alternating current motors with  speed
     reduced  three to five percent for slip.  For  example,  the
     synchronous  speed of a two pole motor is 3600  rpm,  for  a
     four  pole motor it is 1800 rpm, etc.... Speed can  only  be
     varied  in  these increments.  Speed is changed by selecting
     "Motor  speed  change".  As with the case  of  changing  the
     number  of  stages, the displayed curve will be scaled  down
     but not up.

  5.  Changing outlet pressure

     Outlet  pressure  is changed by selecting  "Outlet  pressure
     change".   If  the warning message "Too few stages  to  pump
     anything"  appears,  and the addition  of  a  stage  is  not
     desirable, the calculation may be performed by changing  the
     outlet pressure to a lower value and resetting the number of
     stages to the desired level (it is automatically incremented
     if there are not enough stages).

  6.  Changing flow rate

     Flow  rate  is  changed  by selecting "Discharge  flow  rate
     change".  Setting the flow rate causes a new outlet pressure
     to  be calculated; the flow rate is then calculated from the
     new outlet pressure as a check.




                            EXAMPLES


As  an  example,  a  step  by  step procedure  for  evaluating  a
hypothetical  pump  will  be  given.   Four  example  files   are
supplied;  EX1.DAT,  EX2.DAT, EX3.DAT  and  EX4.DAT.   These  are
typical  examples of pump curves; it is recommended that  one  or
more of the files be retrieved and experimented with so that  the
operation of the program and the dynamics of pump behavior may be
observed.

A. Program Familiarization

In  this  example, familiarity of the program will be  gained  by
entering data and observing the result of varying motor speed.

1)   Start  the  program  and  enter  the  following  pump  curve
     information.  Enter <4> for the number of curve points,  and
     enter the following points:  H1 = 500, Q1 = 0; H2 = 470,  Q2
     =  500; H3 = 350, Q3 = 1000; H4 = 25, Q4 = 1500.  Enter  <5>
     for number of stages, and 1745 for RPM.

2)   Enter the following well specific information:  <65> for the
     specific  capacity, <155> for the standing water  level  and
     <40> for the outlet pressure.

3)   Save  the  file  by selecting "Save current data  file"  and
     entering <EXAMPLE.DAT> at the prompt.

4)   Select  "Draw  pump  curve" and note that  the  line  passes
     through all four points, and press any key when finished.

5)   Enter  the  Evaluation and Results menu  and  calculate  the
     results.   Note that the operating point is outside  of  the
     position  of maximum efficiency, also observe that the  flow
     rate  is  1175  GPM.   Press a key to return  to  the  menu,
     perform an efficiency optimization and recalculate; note the
     flow rate has been set at 965 GPM and the outlet pressure is
     now 84 psi.

6)   Change the motor speed to 1500 RPM and perform an efficiency
     optimization  (this  is  useful for avoiding  out  of  range
     operation  when making large speed changes), then calculate.
     Observe that the curve has been scaled down; by default  the
     original curve is scaled to the largest size available; if a
     higher  RPM  was  chosen, the curve would not  have  changed
     size,  although the shape might change slightly.   The  flow
     rate is 829 GPM and the outlet pressure is now 44 psi.





B.  Selecting an Operating Point

In  this example, the ideal operating point and number of  stages
of a pump will be determined.

1)   Start  the  program  and  enter  the  following  pump  curve
     information.  Enter <4> for the number of curve points,  and
     enter the following points:  H1 = 500, Q1 = 0; H2 = 470,  Q2
     =  500; H3 = 350, Q3 = 1000; H4 = 25, Q4 = 1500.  Enter  <5>
     for number of stages, and 1745 for RPM.

2)   Enter the following well specific information:  <65> for the
     specific  capacity, <155> for the standing water  level  and
     <40> for the outlet pressure.


5)   Enter  the  Evaluation and Results menu  and  calculate  the
     results.   Note that the operating point is outside  of  the
     position  of maximum efficiency, also observe that the  flow
     rate  is  1175  GPM.   Press a key to return  to  the  menu,
     perform an efficiency optimization and recalculate; note the
     the  flow  rate  has  been set at 965  GPM  and  the  outlet
     pressure is now 84 psi.

6)   Let's  say  we  want a flow rate of 1500 GPM  to  match  the
     existing  demands.   We  simply  add  a  stage,  perform  an
     efficiency optimization and recalculate; we repeat this step
     until we are pumping over 1500 GPM, and we select the number
     of stages that gives us the closest flow to 1500 gallons per
     minute.
