CORNELL PUMP COMPANY EFFICIENT BY DESIGN

Transcription

1 PUMP COMPANY FFICINT BY DSIGN &

2 It s unwise to pay too much, but it s worse to pay too little. When you pay too much, you lose a little money, that s all. When you pay too little, you sometimes lose everything, because the thing you bought was incapable of doing the thing it was bought to do. The common law of business balance prohibits paying a little and getting a lot it can t be done. If you deal with the lowest bidder, it is well to add something for the risk you run, and if you do that you will have enough to pay for something better. John uskin

3 Table of Contents Mounting Configuration Quality Features Terminology Fact Finding to Determine Pump Choice Selecting the Pump Multiple Pumps Specific Speed Affinity Laws Pump-ngine Selection ngine Derate Guidelines Average lectric Motor Life Guide to Optimum lectric Motor Life lectric Motor Comparisons lectric Control Panel Data Typical Auto Vacuum Prime Materials of Construction B-10 Bearing Calculation Pump Performance Curves 2.5 WB WB WB YB B B B-Various PM HH x 4 x 14T NHTA NHPP-Various PM Specification Guide Cornell Solids Handling Pumps Lubrication Instructions Start-up Check List Pump Troubleshooting Guide Air Leaks Packing, Wear ings and Coupling Alignment Pump Care

4 Cornell Pump Company P.O. Box 6334 Portland, Oregon Phone: (503) Fax: (503) Web: X MMI Printed and bound in the U.S.A.

5 Mounting Configurations Horizontal Close-Coupled (CC) conomical, compact and efficient. Base-Coupling-Guard Mounted Horizontal Frame Unit Can be mounted with a motor or other driver on a common base. Vertical Close-Coupled (VM) This vertical style is desirable where space is limited. Horizontal Frame (F) Driver flexibility. SA ngine Mount (M) Ideal for remote locations or where electrical power is not available. Trailer or skid mounted. Vertical Coupled (VC) Minimal floor space required. Standard "P" base motor used. Vertical Frame (VF) Driven by flexible shaft from motor above pump. Vertical Mount Inducer (VMI) Provides automatic priming! edi-prime un-dry, automatic dry prime and re-priming capabilities. Close-Coupled Gear Box Vertical Sump (VS) The pump is installed directly in the liquid. Automatic priming. 3

6 Cornell Quality Features FULLY MACHIND IMPLL WITH DOUBL CUVATU VANS BACK PULL-OUT DSIGN FO AS OF MAINTNANC PLACABL, CSSD WA INGS XTNAL HYDAULIC BALANC LIN HAVY, STSS POOF STL SHAFT PLACABL SHAFT SLV MODULA BAING FAM GNOUSLY SIZD BAINGS TO MAXIMIZ B-10 BAING LIF LAG, DP STUFFING BOX FO XTNDD PACKING LIF AND MINIMUM ADJUSTMNTS (MCHANICAL SALS OPTIONAL) SMOOTH CONTOUD SUCTION FO IMPOVD HYDAULIC PFOMANC IGID, HAVY WALLD CONSTUCTION DOUBL VOLUT DSIGN STANDAD ON LAG SIZS 4

7 TH XTNAL HYDAULIC BALANC LIN Unalanced axial forces Holes bored in impeller Sand and silt buildup To lower pressure in the stuffing box (or seal chamber) and to attempt to limit the inherent axial force created by the impeller, traditional centrifugal pump designs use large holes bored through the impeller. Cornell has a more effective method TH XTNAL HYDAULIC BALANC LIN. Balanced axial forces educed Pressure Area Area of turbulence TADITIONAL MTHOD High pressure liquid from the volute passes through the hub ring clearances into the cavity between the stuffing box and the impeller. Liquid returns via the balance line to the region of lower pressure at the pump inlet. This method reduces turbulence, improves hydraulic efficiency, increases the life of packing, mechanical seals and bearings provides positive control of axial forces. educes wear because sand is not trapped behind the impeller, near the shaft. ADVANCD DSIGN FATUS TH DOUBL VOLUT SYSTM MTHOD xternal Hydraulic Balance Line Sand and silt flushed out The Double Volute System enables Cornell single stage, end-suction centrifugal pumps to easily perform big volume and high pressure jobs. As the impeller adds energy to the fluids, pressure increases around the periphery of the volute. On single volute pumps, the increasing pressure acts against the impeller area and creates unbalanced radial forces. By contrast, the Double Volute System effectively balances these forces around the impeller to reduce shaft flexure and fatigue. Cornell s DVS design keeps shafts from breaking, extends the life of packing and mechanical seals, wear rings and bearings maintaining high hydraulic efficiency. Cutwater #1 Cutwater #2 DOUBL VOLUT adial thrust is offset and balanced by the double volute design. 5

8 Terminology PUMPS Pump- A mechanical device that converts mechanical forms of energy into hydraulic energy. Pump Classifications- Generally pumps can be classified into two classifications positive displacement and centrifugal. Positive Displacement Pumps- Operate by reducing the volume of space within the pump that the liquid can occupy. In a reciprocating pump the piston forces the liquid from the cylinder into the discharge line. Centrifugal Pumps- Move liquids by increasing their speed rather than displacing or pushing them. The vanes do work on the fluid to increase the velocity without decreasing the pressure. This increased velocity is then recovered in the casing as increased pressure. TYPICAL CNTIFUGAL PUMP IMPLL In centrifugal pumps, water enters the pump and travels into the impeller through the impeller eye. In general, the larger the impeller eye, the greater the volume in gallons per minute. XAMPL: eciprocating Single or multiple design XAMPL: Centrifugal These can be single and multi-stage open or closed impellers IMPLL Y DISTANC BTWN SHOUDS Piston Plunger Diaphragm otary Gear otary Screw otary Cam adial Flow Mixed Flow Axial Flow Centrifugal Force- According to Websters, is that force which tends to impel a thing, or parts of a thing outward from the center of rotation. Sump- A hydraulic structure that acts as a reservoir from which single or multiple pumps, arranged in parallel, may draw water. Vortex- The phenomenon by which air enters a submerged suction pipe from the water surface. Usually a cause of poor pump performance when the suction pipe is not adequately submerged. Manifold- A hydraulic structure used to distribute water under pressure. Can be used to supply fluid to or receive fluid from a parallel arrangement of multiple pumps. LCTICAL Volt- A unit of electrical potential. A volt is the driving force which causes a current of 1 ampere to flow through a resistance of 1 ohm. Ampere- A unit of electrical current. The unit used to specify the movement of electrical charge per unit time through a conductor. Kilowatt-The unit commonly used to describe electrical power. 1 Kilowatt is equal to approximately 1.34 horsepower. Power- The rate of doing work. Power Factor- The percentage of apparent electrical power (Volts x Amps) that is actually available as usable power. Ohm- The practical unit to measure electrical resistance. esistance of a circuit in which a potential difference of one volt produces a current of one ampere. 6

9 Work- The transference of energy by a process involving the motion of the point of application of a force, as when there is movement against a resisting force or when a body is given acceleration; it is measured by the product of the force and the displacement of its point of application in the line of action. Specific Gravity- The ratio of its density (or specific weight) to that of some standard substance. For liquids, the standard is water (1.0 sp. gr.) at sea level and 60 F. HYDAULICS Hydraulics- The study of fluids at rest or in motion. 3.3 FT. 2.3 FT FT. Fluid- A substance which when in static equilibrium can not sustain tangential or shear forces. This differentiates fluids from solids. However, in motion, fluids can sustain shear forces because of the property of viscosity. A fluid can be a liquid or a gas. Viscosity- The existence of internal friction or the internal resistance to relative motion of the fluid particles with respect to each other. The viscosities of most liquids vary appreciably with changes in temperature, whereas the influence of pressure change is usually negligible. Some liquids have viscosities which change with agitation. Newtonian- A liquid is Newtonian or a true fluid if its viscosity is unaffected by agitation as long as the temperature is constant. xample: Water or mineral oil. Thixotropic- A liquid is thixotropic if its viscosity decreases with agitation at constant temperature. xample: Glues, asphalt, greases, molasses, etc. Dilatant- A liquid is dilatant if the viscosity increases with agitation at constant temperature. xample: Clay slurries and candy compounds. Density- Density is the mass per unit volume of a substance. It is unaffected by the variations in gravity or acceleration. Specific Weight- The weight per unit volume of a substance. The two terms are frequently used interchangeably, though this is incorrect. GASOLIN WAT MOLASSS SP. G. = 0.7 SP. G. = 1.0 SP. G. = PSI 1 PSI 1 PSI Pressure- The force exerted per unit area of a fluid. According to Pascal s principle, if pressure is applied to the surface of a fluid, this pressure is transmitted undiminished in all directions. Atmospheric Pressure- The force exerted on a unit area by the weight of the atmosphere. The standard atmospheric pressure at sea level is 14.7 psi. XAMPL: 1 atmosphere = 14.7 psi ~ 34 feet water 34/14.7 = 2.31 psi = Head in Feet x SP.G Since water weighs.0361 pounds per cubic inch, a column of water one square inch in area and one (1) foot high will weigh.433 pounds. To increase the pressure at the bottom of the column to one (1) psi requires a 2.31 foot high column of water. Gauge Pressure- Is pressure measured relative to local atmospheric pressure. Atmospheric pressure is zero gauge. Absolute Pressure- The sum of atmospheric pressure and gauge pressure. The absolute pressure in a 7

10 perfect vacuum is zero. Absolute pressure of the atmosphere at sea level is 14.7 psi (0 psi gauge). Vapor Pressure- The pressure exerted when a solid or liquid is in equilibrium with its own vapor. Vapor pressure is a function of the substance and of the temperature. Vacuum- Frequently used in referring to pressures below atmospheric. Vacuum is commonly expressed in inches of mercury psi atmospheric pressure equivalent to 30 inches of mercury at sea level. point in the system assuming no friction losses or the performance of work. Static Suction Lift- The vertical distance in feet, when the source of supply is below the pump, from the surface of the liquid to the pump centerline. SUCTION SUPPLY OPN TO ATMOSPH with Suction Lift C L Head- The vertical height of a static column of liquid corresponding to the pressure of a fluid at that point. Head can also be considered as specific work (FT. LB./LB.) necessary to increase the pressure, velocity or height of a liquid to some value. Potential Head- (nergy of position) The work required to elevate a weight to a certain height above some datum or reference plane. P B L S NPSH A = P B - (V P + L S - + h f ) British Thermal Unit (BTU)- The amount of heat required to raise the temperature of one pound of water from 63 to 64 degrees Fahrenheit. BTU s are the unit commonly used to express the potential energy of fuels used in internal combustion engines. SUCTION SUPPLY OPN TO ATMOSPH with Suction Head P B Shut-off Head- Is the head generated by a pump with the discharge valve closed (pump running at zero capacity). Static Pressure Head- (nergy per pound due to pressure). The height to which liquid can be raised by a given pressure. LH NPSH A = P B + L H - (V P + h f ) Velocity Head- (Kinetic energy per pound). The vertical distance a liquid would have to fall to acquire the velocity V. Bernoulli s Theorem- The sum of the three types (elevation, pressure and velocity) of energy (heads) at any point in a system is the same at any other C L Static Suction Head- When the liquid supply is above the pump. The vertical distance from the pump centerline to the surface of the liquid. 8

11 L S = Maximum static suction lift in feet. L H = Minimum static suction head in feet. h f = Friction loss in feet in suction pipe at required capacity. P B = Barometric pressure, in feet absolute. V P =Vapor pressure of the liquid at maximum pumping temperature, in feet absolute. P=Pressure on surface of liquid in closed suction tank, in feet absolute. Static Discharge Head- Vertical distance from pump centerline to the free surface of the liquid in a discharge tank or point of free discharge. TOTAL STATIC HAD STATIC DISCHAG HAD C L STATIC SUCTION LIFT P B L S NPSH A = P - (V P + L S + h f ) P CLOSD SUCTION SUPPLY with Suction Lift CLOSD SUCTION SUPPLY with Suction Head TOTAL STATIC HAD STATIC DISCHAG HAD STATIC SUCTION HAD L H NPSH A = P + L H - (V P + h f ) Total Discharge Head- (hd) Is the sum of: C L Suction Head- (hs) exists when the liquid supply level is above the pump centerline or impeller eye. The total suction head is equal to the static height or static submergence (in feet) that the liquid supply level is above the pump centerline, less all suction line losses including entrance loss, plus any pressure (a vacuum as in a condenser hotwell being a negative pressure) existing at the suction supply source. Caution even when the liquid supply level is above the pump centerline the equivalent of a lift will exist if the total suction line losses (and vacuum effect) exceed the positive static suction head. This condition can cause problems particularly when handling volatile or viscous liquids. (1) Static discharge head. (2) All piping and friction losses on the discharge side including straight runs of pipe, losses at all valves, fittings, strainers, control valves, etc. (3) Pressure in the discharge chamber (if it is a closed vessel). (4) Losses at sudden enlargements (as in a condenser water box). (5) xit loss at liquid discharge (usually assumed to be equal to one velocity head at discharge velocity). (6) Plus any loss factors that experience indicates may be desirable. 9

12 Total Head- (Formerly called Total Dynamic Head). qual to the total discharge head (hd) minus the total suction head (hs) or plus the total suction lift. Net Positive Suction Head equired- (NPSH) The losses from the suction connection to the point in the pump at which energy is added, generally, through the impeller vanes. Determined by test and dependent on pump design, pump size, and operating conditions. Net Positive Suction Head Available- The energy, above the vapor pressure of the fluid, available at the pump suction to push the fluid into the pump. Note: NPSHA depends on the system layout and must always be equal to or larger than the NPSH. Cavitation- A result of inadequate NPSHA. When pressure in the suction line falls below vapor pressure of the liquid, vapor is formed and moves with the liquid flow. These vapor bubbles or cavities collapse when they reach regions of higher pressure on their way through the pump. The violent collapse of vapor bubbles forces liquid at high velocity against the metal, producing surge pressures of high intensity on small areas. These pressures can exceed the compressive strength of the metal, and actually blast out particles, giving the metal a pitted appearance. The other major effects of cavitation are drops in head, flow and efficiency. HAD FT. CAVITATION FFCT ON PUMP CAPACITY H Q CUT OFF POINT CAVITATION NOMAL PFOMANC WITH SUFFICINT NPSHA fittings and changes of section. The Cornell Condensed Hydraulic Data book has typical pipe, valves, and fitting Head Loss Tables. Capacity- Actual pump delivery (usually in gallons per minute in the U.S.A.). Horsepower- Power delivered while doing work at the rate of 550 ft-lb per second or 33,000 ft-lb per minute,.706 BTU s/sec. or.746 kilowatts. Hydraulic Horsepower- (Water Horsepower) The rate at which a pump adds useful energy to a fluid. Brake Horsepower- Total power required by a pump to do a specified amount of work. Brake horsepower equals Hydraulic Horsepower plus mechanical and other losses. FFICINCY Of a Pump Driver- The percentage of input horsepower that is converted to usable brake horsepower by the pump driver. Of a Pump- The percentage of brake horsepower applied to the pump shaft that is converted to usable water horsepower by the pump. Bearing and seal losses are usually deducted from horsepower. ating Curves- (Pump Curve) The most important aspect of any discussion on centrifugal pumps. A graphical representation of a pump s performance, including NPSH requirements, horsepower requirements, etc. over its entire operating range. 100 HAD CAPACITY CAPACITY GPM Pipe Friction- The system loses pressure when the water flowing through the piping encounters resistance. For example, friction occurs along the pipe walls because of roughness. Pressure loss also occurs because of turbulence induced by valves, HAD FT. 0 CAPACITY GPM

13 100 HAD FT HAD FT HAD FT. 0 H Q BAK HOSPOW H Q FFICINCY CAPACITY GPM BHP H Q System Curve- A graphical representation of the relationship between the Total Head and the flow rate for a given fluid system. Simple System Curve- Friction loss increases proportionally to the square of the capacity or velocity. TYPICAL CUVS BHP 500 CAPACITY GPM 500 NPSH CAPACITY GPM BHP 10 Four typical curves may be classed as follows: Steady ising Curve or a rising head capacity characteristic is a curve in which the head rises % FF. NPSH FT. 0 continuously as the capacity is decreased. The rise from best efficiency point to shut-off is about 10 to 20%. Pumps with curves of this shape are used in parallel operation because of their stable characteristics. HAD FT. GPM H Q STADY ISING H Q STABL O.K. IN PAALLL OPATION 2. Drooping Curve characteristic is a curve in which the head capacity developed at shutoff is less than that developed at some capacities. When pumps with drooping characteristics are run on throttling systems, operating difficulties can occur since the system friction curve can intersect the head capacity curve at two points. These pumps will also only operate in parallel when the operating point is below the shut-off head; therefore, parallel operation should be avoided with this curve shape. HAD FT. GPM H Q DOOPING H Q GOOD PFOMANC MAXIMUM Q STABL AT HADS BLOW SHUT-OFF HAD 3. Steep-ising Curve is one where there is a large increase in head between that developed at design capacity and that developed at shut-off. It is best suited for operation where minimum capacity change is desired with pressure changes, such as batch pumping or filter systems. 11

14 HAD FT. H Q STP ISING H Q SHUT -OFF % OF BP HAD STABL GOOD FO PAALLL OPATION IN GNAL In general, it is desirable to choose a pump to operate at maximum GPM FILT SVIC SMALL Q CHANG FO VAIABL HAD efficiency point or slightly to the left of this point. However, with 4. Flat Curve refers to a characteristic in which the head varies slightly with capacity, from shutoff to design capacity. When wide fluctuations of capacity occur with nearly constant pressure requirements this is the pump best used. pumps, as with all commodities, the commercial aspect must be considered. Thus pumps are sold to operate over a wide range, even out H Q FLAT H Q at the end of the rating curve. If HAD FT. LITTL IS OV ANG GOOD FO CHANGING Q WITH LITTL HAD CHANG the NPSH available is sufficient to prevent cavitation, the pump will give satisfactory operation. GPM NOTS: 12

15 Fact Finding to Determine Pump Choice In selecting a pump for a particular job, attention should be given to information gathering. Without proper and specific information, proper selection is impossible. It is often difficult to get information from the user because he either doesn t know the answers or doesn t want you to know about his business. This can waste a lot of time and energy! You must be persistent in getting the information, or you may supply the wrong pump, resulting in back charges for restocking and, consequently, a dissatisfied customer. IT CANNOT B MPHASIZD NOUGH! YOU MUST ASK TH IGHT QUSTIONS. Questions lead to other questions! Ask questions, even unrelated questions can help! They might trigger other questions that are very important to the proper operation of the pump at the site. What are the customer s preferences? Is he a critic of some particular type of pump? Make of pump style of pump? Make of motor style of motor? Make of control style of control? This will influence your selection. You may have been thinking of a Close-Coupled Centrifugal when the customer was thinking in terms of a Canned Turbine. stablish a meeting of minds. Get the facts. Weigh them. Then, make your selection. It may or may not be the type of equipment you first thought of! Ask WHAT the pump is SUPPOSD TO DO. What head is required? What capacity is required? What voltage or power is available? These can be the openers, but there are many others, depending on the job to be done. What is the pumpage? Is the pumpage hot? Check the NPSH. Water flashes at 212 F. Check materials of construction. Bronze expands more than iron. It s possible that a bronze impeller might come off of a particular shaft. Check fluid viscosity. If the fluid cools off, it may thicken, and raise the horsepower requirement. Is the pumpage cold? Check the NPSH. Ammonia boils at -28 F. Check materials of construction; extreme cold may cause embrittlement. Is the pumpage corrosive? What is its PH level? Above 7.0 is alkaline, below 7.0 is acidic. Check materials of construction for compatibility with pumpage. Low PH normally requires brass or stainless steel, high PH normally requires iron or stainless steel. What is, the specific gravity of the pumpage? Acids are normally heavy, as are caustics. This means high horsepower. H BHP BHP BHP HQ Q SP G 1.1 SP G 1.0 SP G

16 The following check list may help you to ask the questions needed to make the right equipment choices: 1. WHAT IS TH PUMPAG? Vapor pressure - Does the pumpage have high vapor pressure? - Check NPSH available against NPSH required. - Does the pumpage have low vapor? Treat 15 PSI as water. Is the pumpage explosive? - Check materials of construction. - Non-ferrous materials should be used to prevent sparking. - Stainless Steel might be desirable. - Quenched glands. Is the pumpage a slurry or sand? - Again, extra horsepower is needed. - xtra capacity to take care of losses due to erosion. - Some slurries are corrosive as well as abrasive, so check materials. Is the pumpage aerated? - Look out for vapor binding. - Check the source of gas entrainment. - Provide bleed-offs in pump to remove air. Is the pumpage viscous? - This can easily lead to high horsepower. - Maximum SSU that can be handled by a centrifugal pumps is about 5000 SSU. - The head-capacity and efficiency curves are drastically reduced. Is the pumpage hazardous to health? - Mechanical seals may be required. - Flushed glands may be required. - Special materials (silver?). - Special pumps (sanitary type). H WAT HQ VISCOUS HQ Is the pumpage carrying solids? - Special pump designs required. - Heavier volutes, Impellers, or Vanes. - ecirculation? - Hard iron or special materials. - High horsepower required. - educed heads. - Pumps should be oversized. Is the pumpage carrying fibers? - What percent? - Is percentage by weight or volume? - In some cases Delta works quite well. - Self-purging action? - Special pump design required. Is the pumpage handling food products? - Single Port Impellers. - Slow speed 5 /sec. velocity is normal. - V-belt drive. 2. WHAT IS TH HAD QUIMNT? Is the discharge head constant as in the filling of a reservoir? (Hooks are O.K. in this curve) Is the discharge head variable like with direct flows into a distribution system? (Hooks in this curve are bad). Is the pump to work at more than one head? Check the efficiency curve. A flat curve is desirable so that the pump will be working near maximum efficiency at both locations. H Q Q 14

17 For more than one head or capacity condition, have you considered: - Variable-speed pumps, or multiple pumps? Is a rising head curve desirable? For a Boiler Feed or levator a flat discharge head is better. - Sprinkler irrigation laterals can be added without a dramatic change in pressure, like Cornell W & Y series. Is a hook in the discharge head curve detrimental? Yes, if head is subject to variation. What is the discharge head in terms of - Feet, PSI, PSI G, PSI A absolute, other? Is the discharge head high pressure 400 to 10,000 feet? If it is, you might consider multi-stage pumps or pumps in series. Is the discharge head medium pressure 100 to 400 feet? If so, you would use a single stage or multi-stage pump. Is the discharge head low pressure 0 to 100 feet? In this range you would normally use a single-stage, low speed pump. 3. WHAT IS TH PUMP CAPACITY? Is the pump high capacity? If so, consider mixed flow or axial flow propeller pumps. Is the pump low capacity? If so, radial or positive displacement pumps should be considered. Is the pump medium capacity? Consider radial or mixed flow pumps. Have you considered dual pumps? Dual pumps have the advantage of stand-by equipment, safety in the event of break down, and usually lower power costs. Is the pump capacity in terms of GPM, cubic foot per second, or second per feet, or barrels per day. Be sure to check the capacity terms used. There is a chance for error here. 4. WHAT IS TH SUCTION CONDITION TH PUMP USS TO OPAT AGAINST? Does it have high suction lift? Medium suction lift? Low suction lift? Is the suction lift critical? If it is in excess of the NPSH required for the pump, you should move the pump closer to the surface of the liquid, or raise the static head of the pump suction, or increase the suction pipe size, to reduce suction system losses. Is the submergence sufficient? Best check the NPSH curve. You might consider the installation of a suction umbrella or a floating platform. How can you tell if the submergence is sufficient or the suction lift critical for the pump selected? There is only one way; check the manufacturer s NPSH curves and compare NPSHA with NPSH. - Is the suction source critical? Are there periodic low flows in the water source? Do you have shut-off controls on your pump to prevent damage? - Is the suction source a sump, a closed tank, a pond, a river, or a pipeline? - Is the suction tank pressurized, if so, what pressure? - What pressure can the pump stand? Is the platform for the pump properly designed? - Do you have to double bolt the pump? - Is the system apt to go higher during static and cause water shock which will damage the pump? - Is the pump mounted at a river location where cross currents could cut the bank out from beneath it and cause the pump to be washed away? - Are there cross currents creating whirlpools and/or aeration that will cause hydraulic instability in the pump? 15

18 What about elevation? Do you know that suction lift ability decreases approximately one foot for every 1,000 feet above sea level due to decreased atmospheric pressure at higher elevations? Is the suction source subject to variation either in level or quantity? - Is the suction source subject to debris? - Is there a submergence limitation? - Do you have a critical velocity? - Will a vortex form? Is the suction source properly designed? - Will it be used for more than one pump? - Is the inlet screened? - Are the screens adequate? - Of proper design? - Are the intake structures baffled? 5. WHAT ABOUT MOTOS? What type of motor enclosure is required? - ODP, WPI, TFC, TNV? Is it xplosion Proof? Is a soft start required or is an across the line start O.K.? Does the user know that motor standards have changed? While 40 C motors were once standard, they are now special. The 60 C motors are now considered standard; however, 75 C motors are standard when a TFC enclosure is furnished. 75 C = 167 F. Does the user know how hot 60 C actually is? Does he realize that he can t hold his hand on a 60 C motor? (60 C = 140 F) 6. WHAT ABOUT TH TYP OF PUMP? Has some particular type of pump given better service? - What has been the history at the site? Does a Horizontal Close-Coupled Centrifugal do the job? They are low cost and don t require much room! Does a Horizontal Frame Mounted do the job? Normal use could be with direct, v-belt drive or variable speed. Does a vertical pump work best? - A Vertical Frame pump such as a Cornell VC type? - A Vertical Frame pump of the Line Shaft type (Cornell VF)? - A Vertical Close-Coupled pump (Cornell VM)? - A Vertical Can? or Turbine? Which would be the best choice? What about the pump s materials of construction? - What has been the user s experience? - Should the pump be all Iron, all Bronze, Stainless Steel, or Cast Steel? If the pump should be all Iron, what type of Iron is best? - Hard/Nodular, Ordinary, High Tensile? - Which would be the best? Is the user aware of all the various types of Iron? If all Bronze,what type? - Standard Commercial, Acid esistant, Heavy Duty? If Stainless Steel: Series ( ), 300 Series ( ), 17-4 PH, Alloy 20? If all Steel, what kind: , 1040, Manganese Self Hardening? Besides knowing what particular type of material to use for the pump s construction, special consideration must also be given to the different metals used for bearings, stuffing boxes, packing, mechanical seals, etc. 16

19 7. WHAT ABOUT PIPING? equirements must be met in piping such as how long the pipe should be, and what size of pipe will work. - What material should the pipe be constructed of for the type of pumpage? What about the friction coefficient? Is it adequate for the pressure required? - Will the pipe carry the capacity required? - Is the friction loss too high? - Do you have a velocity adequate for scouring air/sand? Provided you have satisfied yourself with the information given, you may then proceed with pump application and selection. One last question you should ask yourself before providing your bid or recommendation to the customer: Did I ask enough qualifying questions? NOTS: 17

20 Selecting the Pump HOW TO SLCT A CNTIFUGAL PUMP The pump is selected after all the system data has been gathered and computed. The system TOTAL CAPACITY in gallons per minute and TOTAL HAD in feet must be determined. You should consider suction submergence, NPSH and A, various speeds, other drives (engine, motor, etc.) and all system condition to optimize the selection. TO DTMIN TH SYSTM TOTAL HAD ADD THS FACTOS TOGTH IN FT. 6 NDD PSSU AT ND OF LIN 4 DISCHAG PIP FICTION 5 DISCHAG LIFT SUCTION PIP FICTION 1 2 SUCTION LIFT NOT: B SU TO MULTIPLY PSSU IN P.S.I. BY 2.31 TO CONVT TO FT 7 MISCLLANOUS LOSSS (VALVS, LBOWS, TC.) SUCTION NTANC LOSS 3 TYPICAL PUMP INSTALLATION TOTAL HAD is the SUM of the following: 1.Suction pipe friction (see Condensed Hydraulic Data Book). 2.Suction lift (vertical distance, in feet, from water surface to center of pump inlet). 3.Suction entrance loss (usually figured at one velocity head plus foot valve losses 4.Discharge pipe friction (Condensed Hydraulic Data Book). 5. Discharge lift (vertical distance, in feet from pump to high point in system). 6. Pressure, in feet, for service intended (pressure, in P.S.I., x 2.31 equals feet of head). 7. Miscellaneous losses, in feet (for valves, elbow, and all other fittings, see Condensed Hydraulic Data Book). XAMPL 1: For capacity of 320 GPM, total head in feet is determined as follows: Ft. Suction friction (6 steel pipe, 20 long) 2. 5 Ft. Suction lift 3. 2 Ft. Suction entrance loss Ft. Discharge friction (6 steel pipe,1000 long) Ft. Discharge lift Ft. (43 P.S.I. x 2.31) 7. 5 Ft. Miscellaneous losses 141 Ft. Total Head XAMPL 2: For capacity of 600 GPM, total head in feet is determined as follows: Ft Ft Ft Ft Ft Ft Ft. 190 Ft. Total Head 18

21 SLCTING TH PUMP FO FT. T.H. At 3600 PM efer to the pump performance curve on page 35. The 4WB 40-2, 3560 PM handles the head and capacity with 6.88 Impeller at 72% efficiency and 14 ft. NPSH required. SLCTING TH PUMP FO FT. T.H. efer to the pump performance curve on page 34. The 2.5 WB, 3545 PM, handles the head and capacity with good efficiency. NPSH required is 11 feet. A 20 horsepower 3545 PM motor is required with a 6.56 impeller. At 1800 PM efer to the pump performance curve on page 41. The 4HH 50-4, 1780 PM handles the head and capacity with Impeller at 73% efficiency and 7 ft. NPSH required. NOTS: DATA QUID FO MAKING A SATISFACTOY PUMP SLCTION: 1. equired Head and Capacity. 2. Net Positive Suction Head Available/ equired. 3. Pumpage characteristics: A. Presence of abrasives, size, concentration, specific gravity, other characteristics. B. Viscosity. C. Temperature. D. Corrosive qualities.. Presence of other impurities or gases. F. Specific Gravity. G. Vapor Pressure. 4. Service duty cycle. 5. Type of materials and fittings in connected pipe lines. 6. Previous experiences with the system. 7. Acceptable economic life. 8. Desired pump driver and related data. 9. Safety or downtime consideration. eference: Hydraulic Institute Standards, 13th edition. 19

22 Multiple Pumps If you have large or variable pumping requirements, consider installing multiple pumps rather than a single large pump. Multiple pumps allow you to shut down units under reduced-demand conditions, allowing the on-line units to operate at or near peak efficiency. If you have only a large, single pump, under similar conditions your only options are to throttle the pump or vary the speed. Consequently, your pump could operate at reduced efficiency. Additionally, you can service or repair multiple units during low demand periods to avoid total system shut-downs. Often two small pumps have lower NPSH characteristics than one large pump. When you shop for multiple pump systems, it usually is important to choose pumps with a curve shape that continually rises as the flow reduces. When you operate pumps in parallel and series, contact the pump manufacturer to ensure warrantability of the equipment for your specific application. PUMPS IN PAALLL FLOW G.P.M TDH INCASD FLOW 4B 5WB GPM FLOW IN PAALLL TDH (FT.) B " WB " TOTAL IN PAALLL PUMPS IN PAALLL More than one unit pumping into a common discharge manifold (increases capacity, maintains head). Suction Common discharge Suction NOT: The diagram on this page is intended to show the parallel concept. It is not intended to show proper system design (no valves) or installation of parallel operation. 20

23 INCASD HAD PUMPS IN SIS PUMPS IN SIS The discharge of the first stage is piped into the suction of the second stage (maintains flow, increases head) TDH WB 4B GPM HAD IN SIS G.P.M TDH (FT.) 4B " WB " TOTAL IN SIS NOTS: NOT: The diagram above is intended to show the series concept. It is not intended to show proper system design (no valves) or installation of series operation. 21

24 Specific Speed (N S ) The speed at which an impeller would run if it were proportionally reduced in size so as to deliver 1 GPM against a total dynamic head of 1ft. Specific Speed is a characteristic number which has a great deal of meaning to a pump designer. The intent of this description, however, is not to delve into any theoretical discussion, but to give us exposure to the concept, define what specific speed is, and show how it can have a practical meaning to us in our day to day work with pumps. Specific speed is best defined by its formula: N S = where: n = evolutions per minute Q= B..P. Capacity in GPM at Maximum Impeller Diameter H = Head in feet at B..P. capacity Note that the chart below shows us various configurations of impellers used for pumps, ranging from those radial type impellers for centrifugal pumps through mixed flow and axial flow propeller type pumps. Note also that specific speeds ranging from 500 to 4,000 refer to radial flow type impellers; specific speeds from approximately 4,000 to 10,000 refer to mixed flow type impellers and specific speeds above 10,000 are usually axial flow type impellers. Generally, you can predict the possible efficiency of a pump if you know its capacity at B.P. and the specific speed. n Q H 3/4 where: PM = pump speed GPM = design capacity at best efficiency point for single suction first stage impellers (at max. dia.) NPSH = net positive suction head required in feet (at best efficiency points) *Note: Suction specific speeds can range between 3,000 and 20,000 depending on impeller design, speed, capacity, nature of liquid, conditions of service and degree of cavitation. Cameron Hydraulic Data Indicates: A high suction specific speed may indicate the impeller eye is somewhat larger than normal and consequently the efficiency may be compromised to obtain a low NPSH. Higher values of S may also require special designs and may operate with some degree of cavitation. To avoid marginal designs on the suction side it is desirable for the user or systems engineer to consult with the Pump Manufacturer for suggested design, criteria, and to make certain that the suction conditions finally established will meet the requirements of the pump selected. ADIAL FANCIS MIXD FLOW AXIAL ,000 15,000 G.P.M. N S =.P.M. H 3/4 Suction Specific Speed (S) is a parameter, or index of hydraulic design but here it is essentially an index descriptive of the suction capabilities and characteristics of a given first stage impeller.* It is expressed as: CNTIFUGAL MIXD FLOW POPLL S= PM GPM APPOXIMAT SPCIFIC SPD TO IMPLL SHAP (NPSH) 3/4 22

25 Affinity Laws The affinity laws express the mathematical relationship between the several variables involved in pump performance. They apply to all types of centrifugal and axial flow pumps. They are as follows: 1. With impeller diameter held constant: A. Q 1 N 1 = Q 2 N 2 B. H 1 ( N 1 = H 2 N 2 C. BHP 1 BHP 2 = Q=Capacity, GPM H = Total Head, Feet BHP = Brake Horsepower N = Pump Speed, PM 2. With speed, N, held constant. Using diameter change rather than speed change in the affinity laws is accurate only for small percentages of cutdown, usually 15% or less. ( D. NPSH 1 NPSH 2 = N 1 N 2 A. Q 1 D 1 = Q 2 D 2 B. H 1 ( D 1 = H 2 D 2 C. BHP 1 BHP 2 = ( ( )2 N 1 N 2 D 1 D 2 )3 )2 )2* )3 AFFINITY LATIONSHIP XAMPL Cornell Model 6B 13.5 diameter impeller reference speed 1780 PM. Proposed operational speed 2200 PM. Speed ratio: Affinity laws: Q 1 x = Q 2 H 1 X (1.236) 2 = H 2 BHP 1 X (1.236) 3 = BHP 2 FNC POINT ON 1780 PM PFOMANC CUV: % 14 NPSH HP 1 = 2200 PM 1780 PM = GPM x 150' TDH 3960 x.89 FF. PFOMANC AT 2200 PM: = HP Q 2 = Q 1 x = 3000 GPM x = 3708 GPM H 2 = H 1 x (1.236) 2 = 150 TDH x 1.53 = 230 TDH BHP 2 = BHP 1 x (1.236) 3 = HP x 1.89 = 241 HP *Note: NPSH 2 ~ 22. NPSH does not change exactly as the square of the speed ratio, but this is conservative for speed increases. If speed is being reduced, use the first power of the speed ratio. efer to factory. 23

26 Pump ngine Selection TDH MODL 6B SPD ANG PM 89% PUMP FFICINCY BAK HOSPOW QUID: 3000 GPM x 155' TDH 3960 x.89 PFOMANC CUV BASD ON: 500 levation HG 85 F = 132 HP ACTUAL PUMPING NVIONMNT: 2500 levation 30% elative Humidity 115 F TOTAL HOSPOW QUID: Pump equirement HP Service Factor 10% 13.2 Temp./Humidity Correction 3% 4.0 levation Correction 6% 7.9 TOTAL NT CONTINUOUS HP QUID HP NOTS: 24

27 ngine Derate Guidelines 1. For every 10 F above rated temperature, derate engine performance 1%. 2. For every 1000 FT above rated altitude, derate engine performance 3% for naturally aspirated four-cycle diesel engines and 1% for turbo charged four-cycle diesel engines. 3. Fan/Flywheel losses 5-6%. 10 Stromag torque limitations 362 FT-LBS. DISL FUL: GASOLIN: TOQU (FT-LBS) = WT. 7.1 LBS/GAL WT. 5.9 LBS/GAL 5250 x HOSPOW PM 4. Service factor 10% (allows for engine wear). MODL 685T 3306T PFOMANC CUVS TOQU (FT. LBS) B.S.F.C. (LB/BHP-H) HOS POW TOQU LB FT BSFC LB/BHP-H BHP ATING CUVS B FUL CONSUMPTION A C G/KW/H KW N-M NGIN PM NGIN SPD - PM 25

28 Average lectric Motor Life HP ANG AVAG LIF LIF ANG (Y) (Y) Less than Greater than The average of all units = yr Source: DO eport DO/CS-0147, MOTO FAILU SUVY BY A LAG SVIC SHOP * CAUS OF FAILU TOTAL FAILU (%) Overload (overheating) 27 Normal insulation deterioration (old age) 5 Single phasing 10 Bearing failures 12 Contamination Moisture 17 Oil and grease 20 Chemical 1 Chips and dust 5 TOTAL 97 Miscellaneous 3 *Based on the study of 4000 failures over several years. The major factor in the electric motor life is the life of the insulation system. 26

29 Guide to Optimum lectric Motor Life XTNDING TH LIF OF TH INSULATION SYSTM 1. Supply Voltage: A. Should not be beyond + or - 10% of the nameplate rating with rated frequency AND IN BALANC. B. Voltages should be evenly balanced as close to the reading on the (usually available) commercial volt meter. For continued operation, any voltage unbalance should not exceed 1%. To illustrate the severity of this condition: a 3.5% voltage unbalance will result in approximately a 25% temperature increase. Other side effects will be poor efficiency, increased noise and vibration. 2. Ambient Temperature: A. Protect motor from direct sunlight. B. Provide cooling. C. Derate service factors for elevations above sea level are as follows: UP TO 3300 FT 1.15 SF 6000 FT 1.10 SF FT 1.00 SF 3. Overloading: A. Select your motor carefully to match the load without using a service factor. WATCH TH UNOUT. B. Provide dependable motor starting equipment to protect motor from lightening, single phasing and short cycling. Use the proper overload heater protection. 4. Ventilation: A. Keep screens clean and free from foreign matter. B. If shelter is provided, insure proper ventilation. 5. Lubrication: A. Grease bearings properly as per manufactures instructions. B. Use the proper grease. 6. Location: A. Protect motor from contamination (moisture, dirt, etc). NOTS: 27

30 lectric Motor Comparisons UNIT NGY SAVING IN DOLLAS P HOSPOW* Higher fficiency Lower fficiency Higher fficiency Higher fficiency *Based on 1000-hr/yr operation and 1.0 /kwh power costs. 28

31 lectric Control Panel Data AUTO- TANSFOM STAT TYP AT STA-DLTA STAT TYP SD PAT WINDING STAT TYP PW PIMAY ACTO STAT TYP P ACTO STAT TYP MOTO QUIMNTS Can be used with any standard squirrel cage motor. equires a special motor with 6 leads brought out (Delta wound stator). equires a special motor in which the stator windings are divided into two or more equal parts with six leads provided. Also dual-voltage motors can be used on the lower range. Can be used with any standard squirrel cage motor. Can be used with any standard squirrel cage motor. DSCIPTION OF OPATION The motor is connected to the line through the reduced voltage taps of an auto transformer for the starting interval and then directly across the line for running condition. This method requires two main or line contactors to connect the motor winding in delta connection for running. A third contactor is used to form the star point on the starting step. Like the star-delta starter, this starter requires no external equipment. One winding is connected to the line for starting. After a time interval the second or run contactor connects the other motor winding to the line in parallel with the first winding. A high resistance is connected in series with the motor on starting and after a time interval this resistance is shortcircuited and motor is connected directly to the line. The motor is connected to the line through the reduced voltage taps of a reactor for the starting interval and then directly across the line for running condition. STATING CHAACTISTICS IN PCNT OF NOMAL auto-transformer taps at: % Current % Torque % 100% 33% 33% 100% Line voltage 60% 45% 80 65% 80 65% 64 42% Variable with tape setting and load. ADVANTAGS High torque efficiency. All the power taken from the line, except for transformer losses, is transmitted to the motor. Starting current and torque are easily adjusted by changing auto-transformer taps. Closed circuit transition. The star-delta starter provides low in-rush current with high torque efficiency, without the use of any external equipment. Normally open circuit transition but closed transition can be achieved with the use of resistors Part-winding starting provides one-step acceleration at a reduced current. So that the second current in-rush is not objectionable. Closed circuit transition. This type provides almost as smooth starting as the reactor type starter. The current becomes lower and the voltage at the motor terminals rises as the motor accelerates. Closed circuit transition. This type provides the smoothest starting of all reduced voltage starting methods. More suitable for jogging or inching service. Closed circuit transition. LIMITATIONS Torque remains practically constant for the first step and practically consistent at another value for the second step. Starting characteristics depend on motor design and cannot be adjusted. equires special delta wound motor. equires special motor or dual-voltage motor on low range. Torque efficiency is usually poor for high speed motors. Unavoidable power loss in resistor. Low torque efficiency. Duty cycle limited by thermal capacity of resistor. Taps must be selected on job site to obtain starting voltage level suitable for the load. APPLICATIONS Applications where there are limitations on starting voltage and current. Most widely used. Low starting torque applications. Commercial air conditioning equipment. Geared or belted drives, and other delicate applications. Textile machinery, and other driven loads requiring smooth, shockless starting. APPOX. PIC COMPAISON (% OF TYP AT) 100% 60% 40% More than 100% More than 100% 29

32 Typical Auto Vacuum Prime SLCTIC VACUUM PIM CONTOL PANL (VP-S UNIT) AUTO PIMING SNSO 10 5 VACUUM PUMP NCLOSU (OPTIONAL) HOS VALV 4D MIN " TO 6" KY 1.Bell Suction (if required) w/ Screen 2.45 Bends (together to make Long adius 90 ll) 3.Same as #2 4.ccentric "Suction" educer 5.Concentric Increaser 6.90 lbow w/ Mitered Bends 7.Check Valve 8.Isolation Valve 9.Concentric Increaser 10.Vacuum Priming Chamber (VPS) 11.Pressure Gage & Isolation Cock 12.Pipeline Support 30

33 Materials of Construction Parts Volute Casing Wear ings Impeller Impeller Washer Impeller Key Impeller Screw Suction Cover or Backplate Bracket, Frame Shaft Shaft Sleeve Seal Gland Packing Gland Packing Studs Packing Lantern ing Packing Washer Fasteners Product Flush Line Balance Line Anti-Cavitation Line CLA LIQUID PUMPS SIS W, Y, AND H Standard Material of Construction Cast Iron Bronze Fitted CI BA BZ ST KS SD CI All Iron CI ST KS SD CI ** Frame shafts are SP; Close-coupled shafts are SA Standard Hot Oil Construction CI ST KS SD CI High Pressure CP BA Abrasion esistant ** ** BZ ST KS SD CP Stainless Steel Steel Bronze BA SS SS BA SG SS BA CI CI/SS S CI CI CI CI or ZK CI BZ SD SD SD SD SD SD SD PK PK Consult Factory T T T T T T T BA SS BA SS SS BA S SM SM SM SM SM S S BP SB BP SB SB SB SB SB SY SB SY CA SG CA ST KS SD CA S SD S SC CI SC SS SA SD SC BZ BA BZ S SD BA/BZ CI CI CI CI CI VF Motor Stand CI Primer ed Oxide Base lbow Paint Alkyd Acrylic namel Base lbow Stand Fab. steel or CI BA Bronze (SA 660) ASTM B144-3B C93200 BP Copper Tubing BZ Bronze (SA 40) ASTM B584 C83600 CA Ductile Iron Nodular NI-QT H.T. to BHN Cl Cast Iron ASTM A48, Class 30 CP KS Ductile Iron ASTM A NOD-1B Keystock AISI C1018 MATIAL CODS PK Graphited Acrylic SA SB SC SD S SG Steel AISI 1045 Annealed Steel Tubing Cast Steel AISI 1030, ASTM A216 Stainless Steel AISI 302, 303, 304 Stainless Steel AISI 316, ASTM A296-CF8M Stainless Steel H.T. to BHN SM SA Grade 5 SP Stress Proof qual MOD. SA 1144 SS Stainless Steel AISI 416 ST Stainless Steel AISI 416 H.T. to BHN SY Annealed 304/316 Stainless Steel Tubing T Glass-filled Teflon ZK Zamak-3 or equivalent Note: Special Materials of Construction are available. Consult factory. 31