Pump sizing formula

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# Pump sizing formula

In this article discussed about pump basic formulas with examples like pump power calculation formulaspecific speed of centrifugal pump and affinity laws for centrifugal and displacement pumps. Also provided online calculator for pump power calculation. The work performed by the pump is equal to the weight of liquid pumped in Unit time multiplied by total Head in meters. Pump input BHP is the power delivered to the pump shaft and is designated as brake horsepower. Pump Efficiency is the ratio of pump input and output power.

Pump input power calculation formula or pump shaft power calculation formula. Formula — 5 USCS units. For an electric-motor-driven pumping unit, the overall efficiency is. The specific speed can be used to classify the optimum impeller design. Specific Speed of pump Nq is defined as the speed in RPM at which a geometrically similar impeller would run if it were reduced proportionately in size so as to delivered 75 kg of water per second to the height of 1 m.

The specific speed can be made a truly dimensionless characteristic parameter while retaining the same numerical value by using following equation.

For multistage pumps the developed head H at best efficiency. Consider half total discharge in case of double suction impeller. Radial high head impeller — up to approx. Radial medium head impeller — up to approx. Radial low head impeller — up to approx. Mixed flow impeller — up to approx. Axial flow impeller propeller — approx. Affinity laws for pumps — Please go through the below link. Affinity laws for centrifugal pumps Positive displacement pump affinity laws Pump affinity laws with example.

Pump Efficiency is the most important factor while calculating power consumption. So while selection of the higher rating of pump always choose best efficiency pump set. Click Here. Classification of pumps Types of pumps and their working principles. NPSH calculation Pump suction and delivery lines head loss with online calculator. Thanks for reading this article.

I Hope it may fulfill your requirement. In this article explained about centrifugal section and Sugar house equipment capacity calculation for process house of sugar industryThe theoretical pump power can be calculated as. The shaft power - the power required transferred from the motor to the shaft of the pump - depends on the efficiency of the pump and can be calculated as. The calculator below can used to calculate the hydraulic and shaft power of a pump using Imperial units:. Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro.

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Make Shortcut to Home Screen?Posted on March 07, Want a waterfall feature and don't know how to figure out what size of pump you'll need? Here's some quick, basic information. Our pond construction ebook has more comprehensive information. First, you will need to determine how wide your waterfall weir is. A weir is the area where the water is actually falling down. If your waterfall weir is 36 inches across, you will use 36 inches for part of this equation. Now, for every inch wide your waterfall weir is, you will calculate using - gallons per hour for your waterfall pump size.

If you want a nice, steady flow you may use around GPH or so. Multiply every inch by what type of look you want. In this case, a nice flow of GPH x 36 inches. This equals to a 4, GPH waterfall pump but - there's more and this is where most people make the mistake of getting the wrong size of pump. You also need to work in the length and height the waterfall pump will need to push water. Afterall, the distance you want it to push water and the height will greatly affect what size you need - and, you want to make sure the pump is big enough to have the look you want.

So, you need to measure - not just eyeball it, but measure the distance the pump will be in your pond up to the waterfall weir. This measurement is your length and would also be the length of tubing you need. Next, you'll need to measure the height from the top of the POND water to the top of the waterfall weir. This height is called a 'lift' in pump terminology. Don't measure how deep the pond, only from the surface of the pond. Now, for every foot of height the water has to be pushed from the top of the pond water, we calculate one foot of 'lift'.

Let's say that your waterfall weir is 4' higher than the top of the pond water below. We would use a 4' lift into our equation, but yes, there's more! We also have to add one foot of lift for every 10 FEET in horizontal length the waterfall pump has to push water. In our example, let's say that we need to push the water 30 feet from the pump to the top of the waterfall. We divide the 30 feet by 10 feet and we get 3 feet of lift.

Lastly, we add up the lifts. We had a 4 foot lift in height and we had a 3 foot lift in length and this gives us 7 feet of lift. The magical part is where we put this altogether. In our beautiful wink, wink waterfall example, we would need a waterfall pump that pumps GPH at a 7 foot lift. What this means is that we need to find a pump that will pump that much at that given lift. This is extremely important you understand this; if not, you'll get a pump that is way too small and you may have a drizzle or no water pressure at your waterfall instead of the nice flow that you want.

And, here you would have gotten all of the tubing, had electricity installed, gotten the pump and used it and bam! So, it's important that you figure this out correctly.

In our case, you DO NOT want to look for a box that says it's a GPH pump because this number is most likely at a 0 foot lift or a 1 foot lift - not a 7 foot lift that you need. So, look at the chart and see what that pump will perform at 7 foot lift.Total head and flow are the main criteria that are used to compare one pump with another or to select a centrifugal pump for an application.

Total head is related to the discharge pressure of the pump. Why can't we just use discharge pressure? Pressure is a familiar concept, we are familiar with it in our daily lives.

For example, fire extinguishers are pressurized at 60 psig kPawe put 35 psig kPa air pressure in our bicycle and car tires. For good reasons, pump manufacturers do not use discharge pressure as a criteria for pump selection.

One of the reasons is that they do not know how you will use the pump. They do not know what flow rate you require and the flow rate of a centrifugal pump is not fixed. The discharge pressure depends on the pressure available on the suction side of the pump.

If the source of water for the pump is below or above the pump suction, for the same flow rate you will get a different discharge pressure.

Therefore to eliminate this problem, it is preferable to use the difference in pressure between the inlet and outlet of the pump. The manufacturers have taken this a step further, the amount of pressure that a pump can produce will depend on the density of the fluid, for a salt water solution which is denser than pure water, the pressure will be higher for the same flow rate.

Once again, the manufacturer doesn't know what type of fluid is in your system, so that a criteria that does not depend on density is very useful. You can measure the discharge head by attaching a tube to the discharge side of the pump and measuring the height of the liquid in the tube with respect to the suction of the pump.

The tube will have to be quite high for a typical domestic pump. If the discharge pressure is 40 psi the tube would have to be 92 feet high. This is not a practical method but it helps explain how head relates to total head and how head relates to pressure.

### Hydraulic Pump Calculations

You do the same to measure the suction head. The difference between the two is the total head of the pump. The fluid in the measuring tube of the discharge or suction side of the pump will rise to the same height for all fluids regardless of the density. This is a rather astonishing statement, here's why. The pump produces pressure and the difference in pressure across the pump is the amount of pressure energy available to the system.

If the fluid is dense, such as a salt solution for example, more pressure will be produced at the pump discharge than if the fluid were pure water. Compare two tanks with the same cylindrical shape, the same volume and liquid level, the tank with the denser fluid will have a higher pressure at the bottom. But the static head of the fluid surface with respect to the bottom is the same.

Total head behaves the same way as static head, even if the fluid is denser the total head as compared to a less dense fluid such as pure water will be the same.

This is a surprising fact, see this experiment on video that shows this idea in action. Total head is the height that the liquid is raised to at the discharge side of the pump less the height that it is raised to at the suction side see Figure Why less the height at the suction side?

Because we want the energy contribution of the pump only and not the energy that is supplied to it. What is the unit of head?

Gap between tub and cement board

First let's deal with the unit of energy. Energy can be expressed in foot-pounds which is the amount of force required to lift an object up multiplied by the vertical distance.

## Calculator: Pipe Sizing by Velocity for Water

A good example is weight lifting. If you lift pounds Newtons up 6 feet 1. Head is defined as energy divided by the weight of the object displaced. This is not terribly useful to know for a weight lifter but we will see how very useful it is for displacing fluids. You may be interested to know that foot-pounds of energy is equivalent to 1 calorie.During this COVID pandemic, Pentair global operations and supply teams are working diligently to help ensure our valued customers are getting the best possible service and delivery during this time.

Despite our efforts, shipping delays may occur. Our customer service teams are available and ready to support you through this dynamic situation. As part of its separation into a new pure play water company, a new Pentair website has launched. Please visit the new Pentair. By submitting your information, you confirm that you agree to the storing and processing of your personal information by Pentair Aquatic Eco-Systems, Inc.

Enter the total horizontal pipe length feet for your system. Select nominal pipe diameter inches using the pull-down menu. Enter total pumping lift or height feet water is pumped vertically.

Enter any misc. Enter the number of pipe fittings elbows, tees. Select a pump based on flowrate and total head loss requirements. Filtration Biological Filtration Biomedia Bioreactors. Specialty Protein Skimmers. Liners Pond Liners Tank Liners. Sign Up for Special Offers By submitting your information, you confirm that you agree to the storing and processing of your personal information by Pentair Aquatic Eco-Systems, Inc.

Sign Up. Email Address Send Me Offers. Stay Connected. All rights reserved.There are a few primary factors that go into finding the right size pool pump. First up, you need to figure out how many gallons of water are in your swimming pool.

This calculation differs based on pool shape, but is pretty straightforward. Once you have the approximate number of gallons of water in your pool, we have to figure our minimum flow rate for the pump, using a Gallons Per Minute GPM calculation.

For both traditional chlorine pools and saltwater pools, the industry standard is 2 turnovers per day. Before we get into the calculation, you have a few options here. You can choose to run your pump 24 hours per day decreasing your GPM needs or twice a day in different segments.

The typical two-a-day segments are: 6 hour cycles, 8 hour cycles, and 10 hour cycles. The ultimate goal is efficiency here — balancing electricity bill savings with pump horsepower and balanced water chemistry.

Running at low horsepower for longer periods of time results in a more balanced water chemistry, but can be a sink on your electricity bill. The opposite is true for higher horsepower and shorter run times.

This is where variable speed pool pumps come in handy — they can speed up and slow down when you need them to, resulting in a much safer pool chemistry and energy efficient setup, which is a nice savings on that electric bill.

It is completely dependent on your plumbing system and other pool equipment, all of which should have documentation on maximum flow rates. There are three types of pool filters sand, cartridge, and DE and all of them have different maximum flow rates based on their surface area. Make sure you stay below the maximum flow rates for your filter system or you could end up damaging it.

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Here are the flow rates for common filter types and sizes. As a general rule of thumb, sand filters typically fall between Max GPM per square foot of surface area. Cartridge filters are a lot bigger and a little less exact.

Using the system curve for pump sizing

Pump System Diagram. Usually, the flow rate of liquid a pump needs to deliver is determined by the process in which the pump is installed. This ultimately is defined by the mass and energy balance of the process. For instance the required flow rate of a pump feeding oil into a refinery distillation column will be determined by how much product the column is required to produce.

Another example is the flow rate of a cooling water pump circulating water through a heat exchanger is defined by the amount of heat transfer required. The total differential head a pump must generate is determined by the flow rate of liquid being pumped and the system through which the liquid flows.

Essentially, the total differential head is made up of2 components. The first is the static head across the pump and the second is the frictional head loss through the suction and discharge piping systems.

The static head difference across the pump is the difference in head between the discharge static head and the suction static head. The discharge static head is sum of the gas pressure at the surface of the liquid in the discharge vessel expressed as head rather than pressure and the difference in elevation between the outlet of the discharge pipe, and the centre line of the pump.

The suction static head is sum of the gas pressure at the surface of the liquid in the suction vessel expressed as head rather than pressure and the difference in elevation between the surface of the liquid in the suction vessel and the centre line of the pump. The total frictional head losses in a system are comprised of the frictional losses in the suction piping system and the frictional losses in the discharge piping system.

The frictional losses in the suction and discharge piping systems are the sum of the frictional losses due to the liquid flowing through the pipes, fittings and equipment. The frictional head losses are usually calculated from the Darcy-Weisbach equation using friction factors and fittings factors to calculate the pressure loss in pipes and fittings. In order to calculate the frictional head losses you therefore need to know the lengths and diameters of the piping in the system and the number and type of fittings such as bends, valves and other equipment.

The net positive suction head available NPSHa is the difference between the absolute pressure at the pump suction and the vapour pressure of the pumped liquid at the pumping temperature. It is important because for the pump to operate properly, the pressure at the pump suction must exceed the vapour pressure for the pumped fluid to remain liquid in the pump.

If the vapour pressure exceeds the pressure at the pump suction, vapour bubbles will form in the liquid. This is known as cavitation and leads to a loss of pump efficiency and can result in significant pump damage.

To ensure that the pump operates correctly the net positive suction head available NPSHa must exceed the net positive suction head required NPSHr for that particular pump. The NPSHr is given by the pump manufacturer and is often shown on the pump curve. Pumps are usually driven by electric motors, diesel engines or steam turbines. Determining the power required is essential to sizing the pump driver. Download the Bayt.