Hydraulic ram
Encyclopedia
A hydraulic ram, or hydram, is a cyclic water pump
Cyclic pump
A Cyclic pump is an apparatus which moves a fluid in a periodic uni-directional direction from one containment system to another while overcoming static conditions that would, without intervention, not move...

 powered by hydropower
Hydropower
Hydropower, hydraulic power, hydrokinetic power or water power is power that is derived from the force or energy of falling water, which may be harnessed for useful purposes. Since ancient times, hydropower has been used for irrigation and the operation of various mechanical devices, such as...

. It functions as a hydraulic transformer that takes in water at one "hydraulic head
Hydraulic head
Hydraulic head or piezometric head is a specific measurement of water pressure above a geodetic datum. It is usually measured as a water surface elevation, expressed in units of length, at the entrance of a piezometer...

" (pressure) and flow-rate, and outputs water at a higher hydraulic-head and lower flow-rate. The device uses the water hammer
Water hammer
Water hammer is a pressure surge or wave resulting when a fluid in motion is forced to stop or change direction suddenly . Water hammer commonly occurs when a valve is closed suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe...

 effect to develop pressure that allows a portion of the input water that powers the pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...

 to be lifted to a point higher than where the water originally started. The hydraulic ram is sometimes used in remote areas, where there is both a source of low-head hydropower
Low head hydro power
Low head hydro power applications use river current or tidal flows of 20 meters or less to produce energy. These applications do not need to dam or retain water to create hydraulic head; the head is only a few metres...

, and a need for pumping water to a destination higher in elevation than the source. In this situation, the ram is often useful, since it requires no outside source of power
Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...

 other than the kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...

 of water.

History

In 1772 John Whitehurst
John Whitehurst
John Whitehurst FRS , of Cheshire, England, was a clockmaker and scientist, and made significant early contributions to geology. He was an influential member of the Lunar Society.- Life and work :...

 of Cheshire
Cheshire
Cheshire is a ceremonial county in North West England. Cheshire's county town is the city of Chester, although its largest town is Warrington. Other major towns include Widnes, Congleton, Crewe, Ellesmere Port, Runcorn, Macclesfield, Winsford, Northwich, and Wilmslow...

 in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 invented a manually controlled precursor of the hydraulic ram called the "pulsation engine". The first one he installed, in 1772 at Oulton, Cheshire, raised water to a height of 16 ft (4.9 m). He installed another in an Irish
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 property in 1783. He did not patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

 it, and details are obscure, but it is known to have had an air vessel.

The first self-acting ram pump was invented by the Frenchman Joseph Michel Montgolfier
Montgolfier brothers
Joseph-Michel Montgolfier and Jacques-Étienne Montgolfier were the inventors of the montgolfière-style hot air balloon, globe aérostatique. The brothers succeeded in launching the first manned ascent, carrying Étienne into the sky...

 (best known as a co-inventor of the hot air balloon
Hot air balloon
The hot air balloon is the oldest successful human-carrying flight technology. It is in a class of aircraft known as balloon aircraft. On November 21, 1783, in Paris, France, the first untethered manned flight was made by Jean-François Pilâtre de Rozier and François Laurent d'Arlandes in a hot air...

) in 1796 for raising water in his paper mill
Paper mill
A paper mill is a factory devoted to making paper from vegetable fibres such as wood pulp, old rags and other ingredients using a Fourdrinier machine or other type of paper machine.- History :...

 at Voiron
Voiron
Voiron is a commune in the Isère department in south-eastern France.- History :Voiron long formed part of Savoy, but in 1355 was exchanged by the count with France for Faucigny and Gex.Historical population:* 1901: 12,625- Geography :Voiron stands at a height of 950 ft., on the Morge Voiron...

. His friend Matthew Boulton
Matthew Boulton
Matthew Boulton, FRS was an English manufacturer and business partner of Scottish engineer James Watt. In the final quarter of the 18th century the partnership installed hundreds of Boulton & Watt steam engines, which were a great advance on the state of the art, making possible the...

 took out a British patent on his behalf in 1797. The sons of Montgolfier obtained an English patent for an improved version in 1816, and this was acquired, together with Whitehurst's design, in 1820 by Josiah Easton, a Somerset
Somerset
The ceremonial and non-metropolitan county of Somerset in South West England borders Bristol and Gloucestershire to the north, Wiltshire to the east, Dorset to the south-east, and Devon to the south-west. It is partly bounded to the north and west by the Bristol Channel and the estuary of the...

-born engineer who had just moved to London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

.

Easton's firm, inherited by his son James (1796–1871), grew during the nineteenth century to become one of the more important engineering manufacturers in the United Kingdom, with a large works at Erith
Erith
Erith is a district of southeast London on the River Thames. Erith's town centre has undergone a series of modernisations since 1961.-Pre-medieval:...

, Kent
Kent
Kent is a county in southeast England, and is one of the home counties. It borders East Sussex, Surrey and Greater London and has a defined boundary with Essex in the middle of the Thames Estuary. The ceremonial county boundaries of Kent include the shire county of Kent and the unitary borough of...

. They specialised in water supply and sewerage
Sanitary sewer
A sanitary sewer is a separate underground carriage system specifically for transporting sewage from houses and commercial buildings to treatment or disposal. Sanitary sewers serving industrial areas also carry industrial wastewater...

 systems world-wide, as well as land drainage
Drainage
Drainage is the natural or artificial removal of surface and sub-surface water from an area. Many agricultural soils need drainage to improve production or to manage water supplies.-Early history:...

 projects. Eastons had a good business supplying rams for water supply purposes to large country houses, and also to farms and village communities, and a number of their installations still survived as of 2004.

The firm was eventually closed in 1909, but the ram business was continued by James R Easton. In 1929 it was acquired by Green & Carter , of Winchester
Winchester
Winchester is a historic cathedral city and former capital city of England. It is the county town of Hampshire, in South East England. The city lies at the heart of the wider City of Winchester, a local government district, and is located at the western end of the South Downs, along the course of...

, Hampshire
Hampshire
Hampshire is a county on the southern coast of England in the United Kingdom. The county town of Hampshire is Winchester, a historic cathedral city that was once the capital of England. Hampshire is notable for housing the original birthplaces of the Royal Navy, British Army, and Royal Air Force...

, who were engaged in the manufacturing and installation of the well-known Vulcan and Vacher
Vacher
Vacher is a surname of French origin. People with the name include:*Chris Vacher , British television news presenter*Georges Vacher de Lapouge , French anthropologist and theoretician of eugenics and racialism...

 Rams.
The first US patent was issued to J. Cerneau and S.S. Hallet in 1809. US interest in hydraulic rams picked up around 1840, as further patents were issued and domestic companies started offering rams for sale. Toward the end of the 19th Century, interest waned as electricity
Electricity
Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning, static electricity, and the flow of electrical current in an electrical wire...

 and electric pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...

s became widely available.

By the end of the twentieth century interest in hydraulic rams has revived, due to the needs of sustainable technology in developing countries, and energy conservation
Energy conservation
Energy conservation refers to efforts made to reduce energy consumption. Energy conservation can be achieved through increased efficient energy use, in conjunction with decreased energy consumption and/or reduced consumption from conventional energy sources...

 in developed ones. A good example is AID Foundation International in the Philippines, who won an Ashden Award for their work developing ram pumps that could be easily maintained for use in remote villages. The hydraulic ram principle has been used in some proposals for exploiting wave power
Wave power
Wave power is the transport of energy by ocean surface waves, and the capture of that energy to do useful work — for example, electricity generation, water desalination, or the pumping of water...

, one of which was discussed as long ago as 1931 by Hanns Günther
Walter de Haas
Walter de Haas , who wrote under the pseudonym Hanns Günther was a prolific German author, translator, and editor of popular science books.- Work :...

 in his book In hundert Jahren.

Construction and principle of operation

A hydraulic ram has only two moving parts, a spring or weight loaded "waste" valve
Valve
A valve is a device that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but are usually discussed as a separate category...

 sometimes known as the "clack" valve and a "delivery" check valve
Check valve
A check valve, clack valve, non-return valve or one-way valve is a mechanical device, a valve, which normally allows fluid to flow through it in only one direction....

, making it cheap to build, easy to maintain, and very reliable. In addition, there is a drive pipe supplying water from an elevated source, and a delivery pipe, taking a portion of the water that comes through the drive pipe to an elevation higher than the source.

Sequence of operation

A simplified hydraulic ram is shown in Figure 2. Initially, the waste valve [4] is open, and the delivery valve [5] is closed. The water in the drive pipe [1] starts to flow under the force of gravity and picks up speed and kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...

 until the increasing drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...

 force closes the waste valve. The momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...

 of the water flow in the supply pipe against the now closed waste valve causes a water hammer
Water hammer
Water hammer is a pressure surge or wave resulting when a fluid in motion is forced to stop or change direction suddenly . Water hammer commonly occurs when a valve is closed suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe...

 that raises the pressure in the pump, opens the delivery valve [5], and forces some water to flow into the delivery pipe [3]. Because this water is being forced uphill through the delivery pipe farther than it is falling downhill from the source, the flow slows; when the flow reverses, the delivery check valve closes. If all water flow has stopped, the loaded waste valve reopens against the now static head, which allows the process to begin again.

A pressure vessel [6] containing air cushions the hydraulic pressure shock when the waste valve closes, and it also improves the pumping efficiency by allowing a more constant flow through the delivery pipe. Although, in theory, the pump could work without it, the efficiency would drop drastically and the pump would be subject to extraordinary stresses that could shorten its life considerably. One problem is that the pressurized air will gradually dissolve into the water until none remains. One solution to this problem is to have the air separated from the water by an elastic diaphragm (similar to an expansion tank
Expansion tank
An expansion tank or expansion vessel is a small tank used to protect closed water heating systems and domestic hot water systems from excessive pressure...

); however, this solution can be problematic in developing countries where replacements are difficult to procure. Another solution is to have a mechanism such as a snifting valve
Snifting valve
A snifting valve is an automatic anti-vacuum valve used in a steam locomotive when coasting. The word Snift imitates the sound made by the valve....

 that automatically inserts a small bubble of air with each pump cycle. Another solution is to insert an inner tube of a car or bicycle tire
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...

 into the pressure vessel with some air in it and the valve closed. This tube is in effect the same as the diaphragm, but it is implemented with more widely available materials. The air in the tube cushions the shock of the water the same as the air in other configurations does.

The optimum length of the drive pipe is five-to-twelve times the vertical distance between the source and the pump, or 500-to-1000 times the diameter of the delivery pipe, whichever is less. This length of drive pipe typically results in a period between pulses of one-to-two seconds. A typical efficiency is 60%, but up to 80% is possible. The drive pipe is ordinarily straight but can be curved or even wound in a spiral. The main requirement is that it be inelastic
Elasticity (physics)
In physics, elasticity is the physical property of a material that returns to its original shape after the stress that made it deform or distort is removed. The relative amount of deformation is called the strain....

, strong, and rigid; otherwise, it would greatly diminish the efficiency.

Some later ram designs in the UK called compound rams were designed to pump treated water using an untreated drive water source, which overcomes some of the problems of having drinking water sourced from an open stream.

Common operational problems

Some common operational problems are intrusion of air into the drive pipe, blockage of the intake or valves with debris, knocking due to having too little air in the pressure vessel, freezing in winter and bursting of the delivery pipe if output is blocked or pressure not relieved.

See also

  • Heron's fountain
    Heron's fountain
    Heron's fountain is a hydraulic machine invented by the 1st century inventor, mathematician, and physicist Heron, also known as Hero of Alexandria....

  • Water Rocket
    Water rocket
    A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel—the engine of the rocket—is usually a used plastic soft drink bottle. The water is forced out by a pressurized gas, typically compressed air...

  • The boost converter
    Boost converter
    A boost converter is a power converter with an output DC voltage greater than its input DC voltage. It is a class of switching-mode power supply containing at least two semiconductor switches and at least one energy storage element...

     can be seen as analogous to a hydraulic ram, using the electronic–hydraulic analogy
    Hydraulic analogy
    The electronic–hydraulic analogy is the most widely used analogy for "electron fluid" in a metal conductor. Since electric current is invisible and the processes at play in electronics are often difficult to demonstrate, the various electronic components are represented by hydraulic...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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