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Questions
Q1 - How to read a pump curve?

Imagine that you have a basic water pump with the discharge connected to a short piece of pipe with a pressure gage and a gate valve in it. Suppose you shut the valve and turn the pump on. The pressure gage will reach some maximum and the flow will be zero since nothing can get past the valve. If you now open the valve a little bit there will be some flow and the pressure gage reading will drop a bit. As you open the valve more and more the flow increases and the pressure drops. When the valve is fully open you will get the maximum flow and the pressure will be zero. If you plot these readings on a graph with flow in gallons per minute on the bottom ( x axis) and pressure measured in feet of water on the left ( y axis) you will have a pump curve. This curve is determined at the foundry where the impeller is cast and nothing, within reason, will change it. It is used to tell what flow the pump will produce at any given head pressure. Note that pressure is a measure of resistance to flow. It is the total resistance in a system that determines the flow output of the pump. Without any resistance, the pump delivers its maximum flow. Pumps are quite stupid and totally unaware of what you intend them to do. They deal only in what is real to them and they don't know anything except what is at their suction and what is at their discharge. Pump curves are customarily marked in feet of head because any liquid pumped will be lifted to the same height. This is true whether it is oil, water or molten lead. ( Pressure and energy required are another thing altogether). For water applications, ( pressure in PSI) = feet x .433 or, ( head in feet) = (pressure in PSI) x 2.31 for example: 60 PSI = 138.6 ft



Q2 - How do Centrifugal pumps work? (simplified answer)

A centrifugal pump is basically a rotating shovel for liquid. Each rotation it expels a donut of liquid. The volume of the donut represents how many gallons per minute the pump delivers. The liquid is thrown off the vane tips. At the center of the shaft there is no relative motion but the liquid there moves out to replace the liquid thrown off the tip. This creates a low pressure area at the shaft center, which is also the liquid inlet (pump suction). External pressure on the liquid supply, which may only be atmospheric pressure, forces more liquid into the pump suction. The amount of velocity of the liquid as it leaves the pump determines how much head ( or pressure) the pump will develop. This is determined by the diameter of the vane and how many revolutions per minute it makes (shaft speed). h=V5/2g for you engineers. Pumps are designed around a flow rate which determines how big the case must be to efficiently handle the quantity of water desired. This is indicated by the inlet and outlet pipe sizes but there can be considerable variation. If it gets impractical to make an impeller large enough in diameter to get the head desired, two or more impellers ( stages) can be incorporated into one housing. This is very common in water well pumps where the pump must go down a hole. It is very hard to get a pump with a diameter larger than the hole to go in without the use of a hole stretcher. This device is large, dangerous, and illegal in most states. Ask your well driller.



Q3 - How do you calculate energy consumption in a pump?

A pump converts the energy used to turn its shaft into water energy. The efficiency with which it does so determines what it costs to move the liquid. It takes the same amount of energy to lift one gallon of water two feet as it does to lift two gallons one foot. The formula for water is: Horsepower = (Gallons per minute) x (Total dynamic head in feet) 3960 x pump efficiency This is derived from the definition of horsepower and is always true. For liquids other than water, the specific gravity must be used but that is for another web page. 3960 is a conversion factor to make the units come out right. The word dynamic means the total head is figured when the liquid is in motion and so friction losses must be included.



Q4 - What are the types of Leasing?

Two kinds of leases: – Operating lease or hire-purchase – Financial lease The difference between the two being that operating lease is not a means of financing equipment purchase – only short-term use of equipment: e.g., car rentals. Maintenance and obsolences risk lie with the leasing company as against the lessee in financial leasing.



Q5 - What is Financial Leasing?

• A contractual arrangement that allows one party (the lessee) to use an asset owned by the leasing company (the lessor) in exchange for specific periodic payments. This requires: – Separation of legal ownership from economic use – Credit analysis focuses on lessor’s cash generation capacity to finance lease payments rather than relying on credit history – Security is the asset itself • As such, this product is particularly suitable for new Micro, Small or Medium Sized Enterprises (MSMEs) without a long credit history of financial statements. Why Has leasing grown so fast? Beneficial to both lessee and lessor. For Lessee: • Fewer requirements about balance sheets. • Leasing may be the only source of financing • No outside security/collateral needed • Low documentation cost • Leasing can finance a higher % of equipment than bank loans • Governments allow lessees to deduct full lease payments from their income before tax. For Lessor: • Ownership of asset • Transaction costs lower • Lighter regulations, because they are not deposit taking institutions. • Tax incentives, although they are eroding. • Better control on utilization of funds. Impacts Of Leasing: • Impact on Broadening the Financial Sector Development: Leasing companies have helped develop capital markets by increasing financing options for segments of the market which previously relied on informal financing, supplier credit, and internal cash generation – Filled the gap left by banks • Impact on Capital Markets: As leasing firms grow, their needs for diversified funding sources becomes eminent – leading to the use of securitization, issuances of bonds and other capital instruments. • Increased Competition: The entry of leasing firms in financing the MSME has encouraged competition in many markets, whereby some of the banks started to go down-market in order to serve the smaller clients.



Q6 - Why consider Financial Leasing as an option?

Improved financial management At MWI, we know that pumping equipment can be a significant investment. Time to buy does not always go hand in hand with your needs. Our leasing program can allow you to acquire the pumps you need when you need them – without forsaking your total budget at one time. Tax Benefits: Payments made by lease program participants are considered operating expenses and not capital expenditures, so they can be written off immediately. This often accelerates tax deductions when compared to depreciating assets over five to seven years.



Q7 - What are the advantages of Leasing?

• Smaller initial investment required (better for the liquidity of the leaser) • Payments made over a long period of time – e.g. quarterly, six monthly, yearly, according to what is stated in the contract. • The leaser can Lease approximately four or five pump stations at once rather than buying only one pump station. • Leaser has the option of purchasing the pump station at the end of the contract, at a price agreed upon in the contract. • MWI Egypt is responsible for all maintenance for the pump stations during the contract (MWI offers 24 hour assistance to support any breakdown) • MWI Egypt will always have any spear parts required for the pump station (which saves the Leaser of going through the process of importing any spear parts, which saves time and cuts costs. • Lease program participants are considered operating expenses and not capital expenditures, so payments can be written off immediately.



Q8 - What are the procedures required to go through with Leasing?

1. Agree on the following: • Leasing amount of the pumping station • Method of payment • Time instalments must be paid • Price of the unit if the Leaser decides to purchase the unit at the end of the contract. 2. Signing the contract 3. Supply of the units according to the beginning date of the contract.



Q9 - What is MWI's approach to Technology?

MWI produce efficient and innovative products, with the simple engineering concept which makes the pumps Hi-tech but at the same time easy to deal with due to the basic design. MWI concentrates greatly on research and development, to continuously upgrade the products being produced; to make it easier for the end user, whether it is regarding the size of the components or modifications in the design of the units. For example, the hydraulic tank; which used to be big and bulky is now approximately 1/5 of the original size, which has reduced the size and weight of the unit without effecting efficiency and productivity.




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