Flow rate [m h] Total head [m]

1 Pump technologytermsFor better understanding of the following chapters, we firstly will define and explain thetechnical terms relating to pump technology used in this brochure. The reader will findt hese t er ms i n al phabet i cal order i n t he i ndex. M easures and conversi on f or mulae aresu m m ar i sed i n a t ab l flow rate is the effective volume flowing per unit of time through the dischargeconnect ion of a order to optimize the pump design, the flow rate must be accurately Total head is the effective mechanical energy transferred by a pump to the fluid as afunction of the weight force of the Total head results as follows:H = Hgeo + HV + pIt consist s of : t he dif f erence in height t o over-come bet w een t he suct i on si de andt he discharge side of an inst allat Hdgeo Hsg e o t he f rict ion loss result ing f rom pipewalls, fittings and valves within theplant.

2 HV = HVS+HVd t he pressure dif f erencep = pA pEThe pow er consumpt i on i s t he t ot al ener gy t r ansf er r ed by t he pump t o t he di schar ge f l ow r a t e [ m /h] Total head [m]Power consumpt ionPump technologytermsLooking at t wo parallel plat es wit h t he surf ace A and t he dist ance y, displaced against eachot her as a resul t of a f orce Fact i on with a velocity v, a force Freact i on opposes t o t his displace-ment and i ncr eases w i t h i ncr easi ng dynami c vi scosi t y of t he medi um bet w een t he t w oplat rat io of F t o A is called shear st ress .Th e sh ear st r ess increases in proport ion t o t he shear velocit y D and t he dynamicviscosit y .The rat io of v t o y is def ined as shear velocit y t he result ing dynamic viscosit y :dynamic viscosity Pump technologytermsThus, t he dynamic viscosit y is a characteristic parameter of the fluid concerned anddepends on t he t emper at ur e.

3 Ther ef or e t he vi scosi t y i s al w ays i ndi cat ed t oget her w i t h t hecor r espondi ng t emper at ur viscous f low behaviour:Fluids wit h an ideal viscous f low behaviour are called Newt onian f luids. They are viscousf luids wit h linear molecules. They show a proport ional f low Newt onian f luids are:w a t er, sa l ad o i l , mi l k , su g a rsolut ions, behaviour offluidsPump technologytermsPseudoplastic flow behaviour:The flow behaviour of fluids depends on their physicochemical properties. Adding a fillingagent to a pure solvent, will increase the viscosity and change the flow increasing shear stress, in general the viscosity of highly molecular products inso l u t i o n s an d m el t s t en d s t o d ecr a f low behaviour is called pseudoplast of pseudoplast ic f low behaviour:condensed milk, orange juiceIrreversible flow behaviour:Fluids deformed under applied shear stress in a way that the structure after the destructivephase (shear t ime) can not be rest ored show an irreversible f low result is a permanent , shear t ime dependent change of viscosit f or irreversible f low behaviour.

4 YoghurtPump technologytermsDepending on t he Reynolds number, t he f low passing t hrough a pipe shows specif ic, t ypicalf low pat t erns wit h dif f erent physical propert this context the generation of a laminar or turbulent flow is of particular case of a laminar flow, the particles move in a streamline form and parallely to the pipeaxis wit hout being roughness of t he inside wall of pipes has no ef f ect on t he f rict ion will find a laminar flow mainly with high viscous loss of head changes linearly with the flow case of a t urbulent or vort ical f low t he part icles are mixed because of t he movementalong t he pipe axis and an addit ional, t ransverse movement ..Types of f lowLaminar flowTurbulent flowPump technologytermsThe roughness of the pipe inside has great effect on the friction flows are mainly found with water or fluids similar to loss on pump head varies by square of t he f low velocit Reynolds number describes t he correlat ion bet ween t he f low velocit y v, t he viscosit y and t he inner diamet er of t he pipe Reynolds number has no o w v el o c i t yv[ m / s]Vi sco si t y [Pa s]Inner pipe diamet er di[mm]Densi t y [kg/dm ]Wit h a Reynolds number of 2320 t he laminar f low passes t o a t urbulent f i n ar f l ow < Rekrit = 2320 < turbulent flowExample:In one second, 2 lit res of acet ic acid passes t hrough a pipe wit h a nominal bore of 50 acet i c aci d has a ki nemat i c vi scosi t y of = mPa s = Pa sand a densit y of kg/dm.

5 Is the flow laminar or turbulent?The aver age f l ow vel oci t y amount s t o:Reynolds numberQ [l/s]d [mm]v [m/s]Pump technologytermsThus t he calculat ed Reynolds number is:The Reynolds number exceeds t he crit ical Reynolds number Rekri t=2320. The f low is t is the abbreviation for Net Positive Suct ion HeadBesides t he f low rat e Q and t he pump head H, t he NPSH value is one of t he most import antcharact erist ic paramet er of a cent rif ugal NPSH value of t he pump depends on t he design and speed of t he pump. The higher t hespeed of the pump, the higher the NPSH value will NPSH value is measured on a pump t est st and and cannot be modif ied wit hout sup-pl ement ar y NPSH value of the plant depends on the loss of head including the losses in fittingsand apparat us in t he line of t he plant , and should be always checked by =pressure at the inlet cross section of the plant [bar]pA =pressure at t he out let cross sect ion of t he pl ant [ bar]pD =vapour pressure of t he f luid at t he middleof t he suction connection of t he pump [ bar]pb =air pressure at t he inst allation sit e of t he pump[bar]HVS =loss of head of t he suction line, f rom t he inletcross section of t he plant t o t he inlet crosssection of t he pump [ m]Hsg eo = geodetic suction height (negative, in case off looded suction)

6 [ m] =density of the fluid [kg/m ]vE =inlet flow velocity [m/s]NPSH = p+ p - p g+ v 2g + H- H E bDEsgeo VS N PSH va l u e [ m ]N PSH va l u e of t h epumpN PSH va l u e of t h eplantPump technologytermsIn order t o ensure a correct operat ion of t he pump t he f ollowing condit ion must be given:N PSHplant > N PSHpumpBoiling fluids with a velocity up to 0,3 m/s are a special this case: pE = pD; as v2gE2 and HVS become negligible resulting in:N PSHplant = Hsg e oLoss of headcalculationAlready during design of t he plant and piping layout in f ront of and behind t he pump,losses can be limited when considering: t he pipe diamet er is suf f icient ly dimensioned, less fittings are used, fittings with low friction loss are selected, short pipe runs are diagram shows t he loss of head f or st raight pipe runs as a f unct ion of a pipe lengt h of100 m and a given f low velocit y v depending on t he f low rat e and t he pipe diamet of h ea d i nst raight pipe runsLoss of headcalculationExample:Fl ow rat eQ = 25 m /hPipe diamet erd = 50 mmFrom t he diagram result s.

7 Flow velocit yv = m/sLoss of headHV = 35 m/100 mThe loss of head in f it t ings can be det ermined almost exact ly when using adequat e loss of head in a f it t ing is considered equal t o a st raight pipe wit h calculation is valid only for water and fluids similar to the same diameter of pipes and fittings we can simplify the pipe lengths in meter for fittings(valid for Re 100,000 and roughness k mm)Loss of head causedby fittingsLoss of headcalculationExample:Fl ow rat eQ = 25 m /hSt raight pipe lengt hl = 150 mDi amet erDN = 50 mmElbow 90 4 piecesFr ee- f l ow val ves2 pi ecesf rom di agram (page 16):v = m/ sHV = 35 m/100 m pipe lengt hfrom table :equivalent pipe lengt h 4 elbows:lbend = 4 = pipe lengt h 2 f ree- f low valves:lslide = 2 = mst raight pipe lengt h:lpipe = mtotal pipe lengthltotal = mloss of head:with laminar flow (high viscosities) the loss of head pV can be calculat ed using t heHagen-Poiseuille formula:HV 10 pVvM=Q/A [m/s] [Pa s = kg/m s]l [m]d [m] pV [bar]