# How to read a pump curve



## zanitty (3 يناير 2011)

*بسم الله الهادى​ 

ده شرح عن طريقه قراءه منحنى اى مضخه و فهمه للمبتدأين اللى زى حالاتى لقيته فى احد المواقع فقلت نقراه سوا
​

*

 *SUBJECT : How to read a pump curve 
*​
 






 Please look at the above illustration. You will note that I have plotted the head of the pump against its capacity. The head of a pump is read in feet or meters. The capacity units will be either gallons per minute, liters per minute, or cubic meters per hour.

 According to the above illustration, this pump will pump a 40 capacity to about a 110 head, or a 70 capacity to approximately a 85 head (you can substitute either metric or imperial units as you see fit)

 The maximum head of this pump is 115 units. This is called the maximum shutoff head of the pump. Also note that the best efficiency point (BEP) of this impeller is between 80% and 85% of the shutoff head. This 80% to 85% is typical of centrifugal pumps, but if you want to know the exact best efficiency point you must refer to the manufacturers pump curve.

 Ideally a pump would run at its best efficiency point all of the time, but we seldom hit ideal conditions. As you move away from the BEP the shaft will deflect and the pump will experience some vibration. You'll have to check with your pump manufacturer to see how far you can safely deviate from the BEP aqnd still get satisfactory operation (a maximum of 10% either side is typical)

 Now look at the following illustration:

 







 Note that I have added some additional curves to the original illustration. These curves show what happens when you change the diameter of the impeller.

 Impeller diameter is measured in either inches or millimeters. If we wanted to pump at the best efficiency point with a 11.5 impeller we would have to pump a capacity of 50 to a 75 head.

 The bottom half of the illustration shows the power consumption at various capacities and impeller diameters. I have labeled the power consumption horsepower, but in the metric system it would be called kilowatts

 Each of the lines represents an impeller diameter. The top line would be for the 13 impeller the second for the 12.5 etc. If we were pumping a capacity of 70 with a 13 impeller it would take about 35 horsepower. A capacity of 60 with the 12 impeller would take about 20 horsepower.

 Most pump curves would show you the percent of efficiency at the best efficiency point . The number varies with impeller design and numbers from 60% to 80% are normal.

 When you will look at an actual pump curve you should have no trouble reading the various heads and corresponding capacities for the different size impellers. You will note however, that the curve will usually show an additional piece of information and that is NPSHR which stands for net positive suction head required to prevent the pump from cavitating.

 Depending upon the pump curve you might find a 10 foot (3.0 meter) NPSH required head at a capacity of 480 Gallons per minute (110 cubic meters per hour) if you were using a 13 inch (330 mm.) diameter impeller.

 You should keep in mind that the manufacture assumed you were pumping 20° C ( 68° F ) fresh water and the N.P.S.H. Required was tested using this assumption. If you are pumping water at a different temperature or if you are pumping a different fluid, you are going to have to add the vapor pressure of that product to the N.P.S.H. Required. The rule is that Net Positive Suction Head Available minus the Vapor Pressure of the product you are pumping (converted to head) must be equal to or greater than Net Positive Suction Head Required by the manufacturer.

 





 Suppose we wanted to pump some liquid Butane at 32 degrees Fahrenheit (0 degrees Centigrade) with this pump. If we look at the curve for Butane on a vapor pressure chart similar to the one shown in the charts and graphs section of this web site you will note that Butane at 32°F needs at least 15 psi (1,0 Bar) to stay in a liquid state. To convert this pressure to head we use the standard formula :

 





 In other words Butane at this temperature would not vaporize as long as I had the above absolute heads available at the suction side of the pump.

المصدر
http://www.mcnallyinstitute.com/02-html/2-03.html
​


----------



## zanitty (3 يناير 2011)

و ده شرح من موقع اخر




Cole-Parmer makes every attempt to publish a representative flow versus back pressure curve. In many cases, we can also furnish performance curves that quantify parameters such as NPSHreq. 
*NPSHreq:*  The Net Positive Suction Head that must be available to the pump for cavitation-free operation. NPSHreq is typically expressed in either foot of head or units of pressure.
​*Best Efficiency Point* 

The Best Efficiency Point is the point at which effects of head (pressure) and flow converge to produce the greatest amount of output for the least amount of energy. 
NPSHavail = ha - hvpa - hst - hfs when suction lifts fluid

NPSHavail = ha - hvpa + hst - hfs for flooded suction 

ha = absolute pressure (in feet of the liquid being pumped) on the surface of the liquid supply level (this will be barometric pressure if suction is from an open tank or sump; or the absolute pressure existing in a closed tank such as a condenser hotwell or deareator). 

hvpa = The head in feet corresponding to the vapor pressure of the liquid at the temperature being pumped. 

hst = Static height in feet that the liquid supply level is above or below the pump centerline or impeller eye. 

hfs = All suction line losses (in feet) including entrance losses and friction losses through pipe, valves, and fittings. 

​*Friction Losses* 

Friction losses in pipes is commonly calculated with the Darcy-Weisbach equation, in which: 
hf = f x  L  x  V2  D 2g hf = friction loss in feet of liquid f = friction factor—a dimensionless number which has been determined experimentally and for turbulent flow depends on the roughness of the pipe's interior surface and the Reynolds number. L = pipe length in feet D = average inside diameter of pipe in feet V = average pipe velocity in ft/sec g = gravitational constant (32.174 ft/sec2)

​*Reynolds Number* 

The Reynolds number is determined by an equation in which: 

  R =  VD  n D = inside diameter of pipe in feet
V = average pipe velocity in ft/sec
n = kinematic viscosity in ft2/sec

​ *Friction Factor* 

In the case of a viscous (laminar) flow, in which the Reynolds number is below 2000, the friction factor is determined by the following equation in which:  

  f =  64  R R = Reynolds number

In the case of turbulent flow, in which the Reynolds number is above 4000, the friction factor can be determined by the following equation developed by C. F. Colebrook: 

  ρ = [-2 log10 (  Ε  + 2.51 )] -z 3.7D R√f ρ = density at temperature and pressure at which liquid is flowing in lb/ft2
Ε = absolute roughness (see Pipe Absolute Roughness table below)
D = inside diameter of pipe in feet
R = Reynolds number
f = friction factor
z = absolute or dynamic viscosity in centerpoises

المصدر
http://www.coleparmer.com/techinfo/techinfo.asp?ID=629&htmlfile=ReadPumpCurve.htm


----------



## aati badri (3 يناير 2011)

ما اروعك


----------



## Atatri (3 يناير 2011)

بارك الله فيك


----------



## اسامة اشرى (3 يناير 2011)

الله ينور


----------



## محب الحرمين (3 يناير 2011)

ممتاز يا باشا الله ينور عليك


----------



## جون سينا1 (3 يناير 2011)

شكرا


----------



## عادل ابراهيم 60 (4 يناير 2011)

شكر الله لك وجعله في موازين حسناتك


----------



## zanitty (4 يناير 2011)

شكرا لكم جميعا على ردودكم المحفذه 

الصفحه دى فيها شويه شرح بالحركه لحاجات كتير فى نظريه عمل المضخات

http://www.grundfos.com/training-events/elearning/pump-theory.html


----------



## gold_fire_engineer (4 يناير 2011)

شكراً لك وبارك الله فيك


----------



## جسر الأمل (4 يناير 2011)

*جزاك الله خيرا ....والله مشاركاتك كلها روعة ...ربي يزيدك علم ونور*


----------



## دكتور صبرى سعيد (4 يناير 2011)

انتقاء لموضوع هام جدا 
بارك الله فيكم و دائما رائد في اختياراتك


----------



## zanitty (4 يناير 2011)

جسر الأمل قال:


> *جزاك الله خيرا ....والله مشاركاتك كلها روعة ...ربي يزيدك علم ونور*





مهندس صبري سعيد قال:


> انتقاء لموضوع هام جدا
> بارك الله فيكم و دائما رائد في اختياراتك


جزاكم الله خيرا
اخجلتم تواضعنا 
هذا غيض من فيض علمكم


----------



## حسام محمد (4 يناير 2011)

أخي العزيز والغالي جدا ع قلبي ....
أول شي الله يعطيك الف عافية والله يوفقك ويفرج همك وكربتك ويرزقك على عدد مافي السماء من نجوم يا نجمة هذا المنتدى . 
والي عتب على الأخوة القائمين على هالمنتدى الجميل 
ليش لحد الآن ماعطوك ولا وسام للتميز ؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟؟
اقسم بالله انت بتستاهل كل الأوسمة الموجودة بالمنتدى ... ولازم يخصصوك بكم وسام الك لحالك وبس 
مع خالص احترامي الشديد لكل الأخوة اللي هنن بالاساس أساتذة الي 
بس أنت - متل ما منحكي باللهجة السورية - معلم 
يأحلى معلم والله 
الله يوفقك يا غالي ومن حسن إلى أحسن بإذن الله 
أخوك وتلميذك .......... حسام محمد


----------



## abdelrahim (7 يناير 2011)

*شكر الله لك وجعله في موازين حسناتك*


----------



## thaeribrahem (8 يناير 2011)

مشكور يا استاذ


----------



## نصير عبد الرزاق (8 يناير 2011)

*بارك الله فيك يا أخ زناتي . وكشرا*​


----------



## كرم الحمداني (8 يناير 2011)

عاشت الايادي ياورد


----------



## احمدعبدالمؤمن (16 يناير 2011)

ربنا يجزيك كل خير


----------



## حمدكوم (24 يناير 2011)

السلام عليكم
اشكر الاخ على هذه المعلومات القيمة وارجو من الله عز و جل ان يجعله في ميزان حسناته
الاخ العزيز هناك برنامج مختص بهذه المعلومات بحيث عندما تعطيه البيانات مثل نوع المائع وقطر الداخل والخارج للمضخة والضغط اللازم سوف يعطيك نتائج على شكل كيرفات مع القدرة اللازمة لتشغيل المضخة .
الاخ العزيز اذا حصل على هذا البرنامج او اي حد ثاني ارجو ارساله لي مع كل التقدير لكم


----------



## zanitty (24 يناير 2011)

هذه البرامج مساحتها كبيره جدا اخى بحيث يمكن رفعها الى الشبكه 
يمكنك طلب برنامج مضخات جراند فوس من المورد القريب لمنطقتك فهو يقوم بنفس الوظائف التى ذكرتها
شكرا لك على اطرائك


----------



## samer osman (10 فبراير 2011)

كنت ابحث فترة عن مفهوم الhead suction واخيرا عثرت عليه منك...
شكرا جذيلا لك اخى


----------



## nofal (22 فبراير 2011)

جزاك الله خيرا


----------



## حسن مصطفي احمد (12 مارس 2011)

جزاكم الله الجنة


----------



## م/مصطفى الششتاوى (6 أبريل 2011)

*التكييف ومحتوياته ومصطلحات تخصه جميلة جدا وباسلوب بسيط*
http://www.arab-eng.org/vb/t205121.html


----------



## hatem elsaka (6 أبريل 2011)

*جزاكم الله الجنة*​


----------



## كرم الحمداني (6 أبريل 2011)

شكرا جزيلا


----------



## mechanic power (6 أبريل 2011)

الله ولى التوفيق


----------



## pora (6 أبريل 2011)

فعلا التميز له ناسة تسلم ايدك


----------



## محمد سلامه الراضى (7 مايو 2011)

جزاك الله خيرا


----------



## ابن العميد (8 مايو 2011)

ماشاء الله شرح هادي جدا


----------



## نصير عبد الرزاق (8 مايو 2011)

بارك الله فيك يا أخي زناتي . وشكرا


----------



## Ashraf Naeem (8 مايو 2011)

شكرا على مجهودك الرائع


----------



## علاء المشني (12 مايو 2011)

تحيا مصر...ومشكور يا ورده


----------



## safa aldin (13 مايو 2011)

بارك الله فيك


----------



## mohamedtop (29 أغسطس 2011)

ربنا يباركلك وكل عام وانت وكل الزملاء بالف خير بمناسبة العيد اعاده الله علينا باليمن والبركات


----------



## محمد العطفي (30 ديسمبر 2011)

بارك الله فيك


----------

