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58-468: Water aeration is the process of increasing or maintaining the oxygen saturation of water in both natural and artificial environments. Aeration techniques are commonly used in pond, lake, and reservoir management to address low oxygen levels or algal blooms. Water aeration is often required in water bodies that suffer from hypoxic or anoxic conditions, often caused by upstream human activities such as sewage discharges, agricultural run-off, or over-baiting

116-444: A pond or lake and thus reduce thermal stratification . Once circulated water reaches the surface, the air-water interface facilitates the transfer of oxygen to the lake water. Natural resource and environmental managers have long been challenged by problems caused by thermal stratification of lakes. Fish die-offs have been directly associated with thermal gradients, stagnation, and ice cover. Excessive growth of plankton may limit

174-409: A 74-ha oxic zone. It was upgraded in 2019 to fine-bubble injectors to provide more oxygen directly. Many water treatment processes use a variety of forms of aeration to support biological oxidative processes. A typical example is activated sludge which can use fine or coarse bubble aeration or mechanical aeration cones which draw up mixed liquor from the base of a treatment tank and eject it through

232-530: A drive shaft and bolted joint to transmit power to a secondary implement or accessory. In the case of a marine application, such as shafts may be used to power fire pumps. In aircraft applications, such an accessory drive may be used in conjunction with a constant speed drive . Jet aircraft have four types of PTO units: internal gearbox, external gearbox, radial drive shaft, and bleed air, which are used to power engine accessories. In some cases, aircraft power take-off systems also provide for putting power into

290-600: A fishing lake. Aeration can be achieved through the infusion of air into the bottom of the lake , lagoon or pond or by surface agitation from a fountain or spray-like device to allow for oxygen exchange at the surface and the release of gasses such as carbon dioxide , methane or hydrogen sulfide . Decreased levels of dissolved oxygen (DO) is a major contributor to poor water quality. Not only do fish and most other aquatic animals need oxygen, aerobic bacteria help decompose organic matter. When oxygen concentrations become low, anoxic conditions may develop which can decrease

348-430: A greater oxygen transfer rate. One of the drawbacks to fine bubble aeration is that the membranes of ceramic diffusers can sometimes clog and must be cleaned in order to keep them working at their optimum efficiency. Also, they do not possess the ability to mix the water column as well as other aeration techniques, such as coarse bubble aeration. ( See also Lake de-stratification ) Circulators are commonly used to mix

406-531: A hydraulic pump directly to the PTO: for example, fire truck pumps. A "sandwich" type split shaft unit is mounted between engine and transmission and used on road maintenance vehicles, fire fighting vehicles and off-road vehicles. This unit gets the drive directly from the engine shaft and can be capable of delivering up to the complete engine power to the PTO. Usually these units come with their own lubricating system. Due to

464-412: A key role in the breakdown of organic matter in soils. Higher oxygen saturation allows aerobic bacteria to persist, which breaks down decaying organic material in soils much more efficiently than anaerobic bacteria. Thus, soils with high oxygen saturation will have less organic matter per volume than those with low oxygen saturation. Environmental oxygenation can be important to the sustainability of

522-407: A large surface area through which oxygen can be transferred. Upon return, these droplets mix with the rest of the water and thus transfer their oxygen back to the ecosystem. Fountains are a popular method of providing surface aeration because of the aesthetic appearance that they offer. However, most fountains are unable to produce a large area of oxygenated water. Also, running electricity through

580-610: A leaflet. Agricultural PTOs are standardized in dimensions and speed. The ISO standard for PTOs is ISO 500 , which as of the 2004 edition was split into three parts: The original type (designated as Type 1) calls for operation at 540 revolutions per minute (rpm). A shaft that rotates at 540 rpm has six splines on it, and a diameter of 1 + 3 ⁄ 8 inches (35 mm). Two newer types, supporting higher power applications, operate at 1000 rpm and differ in shaft size. Farmers typically differentiate these two types by calling them "large 1000" or "small 1000" as compared to

638-429: A mixing of the water. In comparison to other aeration techniques, coarse bubble aeration is very inefficient in the way of transferring oxygen. This is due to the large diameter and relatively small collective surface area of its bubbles. Fine bubble aeration is an efficient way to transfer oxygen to a water body. A compressor on shore pumps air through a hose, which is connected to an underwater aeration unit. Attached to

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696-470: A particular ecosystem . The US Environmental Protection Agency has published a table of maximum equilibrium dissolved oxygen concentration versus temperature at atmospheric pressure. The optimal levels in an estuary for dissolved oxygen is higher than six ppm. Insufficient oxygen ( environmental hypoxia ), often caused by the decomposition of organic matter and nutrient pollution , may occur in bodies of water such as ponds and rivers , tending to suppress

754-519: A solution to help improve water quality. Aeration of hypoxic water-bodies seems an appealing solution and it has been tried successfully many times on freshwater ponds and small lakes. However no one has undertaken an aeration project as large as an estuary . A 353-hectare portion of the bay connected to the Rock Creek has been aerated using pipes since 2016. The system started as a large-bubble system intended mainly for de-stratification, creating

812-441: A still larger type (designated as Type 4) has been added to ISO 500. It operates at a higher rotational speed of 1300 rpm in order to allow for power transfer at reduced levels of torque. The shaft has 22 splines with a major diameter of 57.5 millimeters (mm). It is meant to handle PTO powers up to 450 kilowatts (kW), or roughly 600 horsepower (hp). All four types rotate counterclockwise when viewed looking back from inside

870-410: A surface aerator is limited to a small area as they are unable to add circulation or oxygen to much more than a 3-metre radius. This circulation and oxygenating is then limited to the uppermost portion of the water column, often leaving the bottom portions unaffected. Low speed surface aerators can also be installed on floats. Paddlewheel aerators also utilize air-to-water contact to transfer oxygen from

928-414: A very high oxygen transfer efficiency (OTE), sometimes as high as 15 pounds of oxygen / (horsepower * hour) (9.1 kilograms of oxygen / (kilowatt * hour)). On average, diffused air aeration diffuses approximately 2–4 cfm (cubic feet of air per minute) (56.6-113.3 liters of air per minute), but some operate at levels as low as 1 cfm (28.3 L/min) or as high as 10 cfm (283 L/min). Fine bubble diffused aeration

986-412: Is able to maximize the surface area of the bubbles and thus transfer more oxygen to the water per bubble volume. Additionally, smaller bubbles take more time to reach the surface so not only is the surface area maximized but so are the time each bubble spends in the water, allowing it more opportunity to transfer oxygen to the water. As a general rule, smaller bubbles and a deeper release point will generate

1044-438: Is mounted to the truck's drive shaft to provide power to the PTO. Such a unit is an additional gearbox that separates the vehicle's drive shaft into two parts: The unit itself is designed to independently divert the engine's power to either the axle-facing shaft or the additional PTO output shaft. This is done by two independent clutches like tooth or dog clutches, which can be operated at total driveline standstill only. Because

1102-474: Is one of several methods for taking power from a power source, such as a running engine , and transmitting it to an application such as an attached implement or separate machine. Most commonly, it is a splined drive shaft installed on a tractor or truck allowing implements with mating fittings to be powered directly by the engine. Semi-permanently mounted power take-offs can also be found on industrial and marine engines. These applications typically use

1160-413: Is pumped from an on-shore air compressor . through a hose to a unit placed at the bottom of the water body. The unit expels coarse bubbles (more than 2mm in diameter), which release oxygen when they come into contact with the water, which also contributes to a mixing of the lake's stratified layers. With the release of large bubbles from the system, a turbulent displacement of water occurs which results in

1218-540: Is pumped, from five sites around the Bay, through a series of steel reinforced rubber pipelines, laid on the beds of the Bay and Rivers Taff and Ely. These are connected to approximately 800 diffusers. At times this is insufficient and the Harbour Authority uses a mobile oxygenation barge built by McTay Marine with liquid oxygen stored in a tank. Liquid oxygen is passed through an electrically heated vapouriser and

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1276-629: The National Safety Council , six percent of tractor related fatalities in 1997 in the United States involved the PTO. Incidents can occur when loose clothing is pulled into the shaft, often resulting in bone fractures , loss of limbs , other permanent disabilities, or death to its wearer. On April 13, 2009, former Major League Baseball star Mark Fidrych died as a result of a PTO related accident ; "He appeared to have been working on his truck when his clothes became tangled in

1334-403: The tissues of the body. In this case blood is oxygenated in the lungs , where oxygen molecules travel from the air into the blood. Oxygen saturation (( O 2 ) sats) measures the percentage of hemoglobin binding sites in the bloodstream occupied by oxygen. Fish, invertebrates, plants, and aerobic bacteria all require oxygen. In aquatic environments, oxygen saturation is a ratio of

1392-419: The transmission , the exact point along the gear train where the power is taken off determines whether the PTO can be run independently of vehicle travel ( ground speed ). Early PTOs were often taken off the main output shaft, meaning that the vehicle had to be "in gear" in order to run the PTO. Later this was improved by so-called live PTO (LPTO) designs, which allow control of the PTO rotation independently of

1450-475: The Cockshutt Model 30 tractor with LPTO. Live PTOs eventually became a widespread norm for new equipment; in modern tractors, LPTO is often controlled by push-button or selector switch. This increases safety of operators who need to get close to the PTO shaft. The PTO, as well as its associated shafts and universal joints , are a common cause of incidents and injury in farming and industry. According to

1508-459: The Type 1 which is commonly referred to as the "540". All new types (2, 3, and 4) use involute splines, whereas Type 1 uses straight splines. Inch-denominated shafts are round, rectangular, square, or splined; metric shafts are star, bell, or football -shaped. Due to ever-increasing horsepower requirements from farm implements, and higher horsepower engines being installed in farm tractors,

1566-470: The ability of the water body to support life. Any procedure by which oxygen is added to water can be considered a type of water aeration. There are many ways to aerate water, but these all fall into two broad areas – surface aeration and subsurface aeration . A variety of techniques and technologies are available for both approaches. Natural aeration is a type of both sub-surface and surface aeration. It can occur through sub-surface aquatic plants. Through

1624-404: The air in the atmosphere to the water body. They are most often used in the aquaculture (rearing aquatic animals or cultivating aquatic plants for food) field. Constructed of a hub with attached paddles, these aerators are usually powered by a tractor power take-off ( PTO ), a gas engine , or an electric motor . They tend to be mounted on floats . Electricity forces the paddles to turn, churning

1682-461: The air where oxygen is entrained in the liquor. Oxygen saturation Oxygen saturation can be measured regionally and noninvasively. Arterial oxygen saturation (Sa O 2 ) is commonly measured using pulse oximetry . Tissue saturation at peripheral scale can be measured using NIRS . This technique can be applied on both muscle and brain. In medicine , oxygen saturation refers to oxygenation , or when oxygen molecules ( O 2 ) enter

1740-438: The concentration of "dissolved oxygen " (DO, O 2 ), to the maximum amount of oxygen that will dissolve in that water body, at the temperature and pressure which constitute stable equilibrium conditions. Well-aerated water (such as a fast-moving stream) without oxygen producers or consumers is 100% saturated. Stagnant water can become somewhat supersaturated with oxygen (i.e., reach more than 100% saturation) either because of

1798-493: The continuous and intermittent torque that can be applied through them and different models will offer different "PTO shaft rotation to engine RPM" ratios. In the majority of cases, the PTO will connect directly to a hydraulic pump . This allows for transmission of mechanical force through the hydraulic fluid system to any location around the vehicle where a hydraulic motor will convert it back into rotary or linear mechanical force. Typical applications include: A split shaft PTO

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1856-508: The diameter, the higher the SOE and mixing. A fountain consists of a means of squirting the water upwards into the air. Typically this may be done using a motor that powers a rotating impeller . The impeller pumps water from the first few feet of the water and expels it into the air. This process utilizes air-water contact to transfer oxygen. As the water is propelled into the air, it breaks into small droplets. Collectively, these small droplets have

1914-451: The engine during engine start. See also Coffman starter . Various power transmission methods were available before power take-offs became common, but there were applications which would benefit more from some of the attributes that PTOs would provide. Flat belts were generally only useful for applications where the engine was stationary, such as factory steam engines , portable stationary engines , or traction engines parked in front of

1972-469: The gas is injected into a stream of water which is pumped from, and returned to, the bay. The barge is capable of dissolving up to 5 tonnes of oxygen in 24 hours. Similar options have been proposed to help rehabilitate the Chesapeake Bay where the principal problem is lack of filter-feeding organisms such as oysters responsible for keeping the water clean. Historically the Bay's oyster population

2030-416: The main gearbox changes the rotation speed by selection of a gear, the PTO cannot be operated while the vehicle is moving. On 4x4 vehicles, only the rear drive shaft is used by the split shaft PTO gearbox, requiring the vehicle's 4x4 drive scheme to be of the selectable 4WD type to keep the front axle drive shaft completely decoupled during PTO operation. It is also possible to connect something other than

2088-517: The natural process of photosynthesis, water plants release oxygen into the water providing it with the oxygen necessary for fish to live and aerobic bacteria to break down excess nutrients. Oxygen can be driven into the water when the wind disturbs the surface of the water body and natural aeration can also occur through a movement of water caused by an incoming stream , waterfall , or even a strong flood . In large water bodies in temperate climates, autumn turn-over can introduce oxygen rich water into

2146-437: The oxygen-poor hypolimnion . The low speed surface aerator is a device for biology aeration with high efficiency. These devices are often in steel protected by epoxy coating and generate high torque. The mixing of water volume is excellent. The common power is going from 1 up to 250kw per unit with an efficiency (SOE) around 2 kgO2/kw. Low speed aerator are used mostly for biology plant aeration for water purification. The higher

2204-438: The plant populations , resulting in a reduction of dissolved oxygen levels, rendering areas of the bay unsuitable for aerobic aquatic life. In a symbiotic relation the plants provide the oxygen needed for underwater organisms to proliferate, and in exchange the filter feeders keep the water clean and thus clear enough for plants to have sufficient access to sunlight. Researchers have proposed oxygenation through artificial means as

2262-404: The presence of aerobic organisms such as fish . Deoxygenation increases the relative population of anaerobic organisms such as plants and some bacteria , resulting in fish kills and other adverse events. The net effect is to alter the balance of nature by increasing the concentration of anaerobic over aerobic species . Power take-off A power take-off or power takeoff ( PTO )

2320-401: The presence of photosynthetic aquatic oxygen producers or because of a slow equilibration after a change of atmospheric conditions. Stagnant water in the presence of decaying matter will typically have an oxygen concentration much less than 100%, which is due to anaerobic bacteria being much less efficient at breaking down organic material. Similarly as in water, oxygen concentration also plays

2378-427: The recreational use of lakes and the commercial use of lake water. With severe thermal stratification in a lake, the quality of drinking water also can be adversely affected. For fisheries managers, the spatial distribution of fish within a lake is often adversely affected by thermal stratification and in some cases may indirectly cause large die-offs of recreationally important fish. One commonly-used tool to reduce

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2436-496: The severity of these lake management problems is to eliminate or lessen thermal stratification through aeration. Many types of aeration equipment have been used to reduce or eliminate thermal stratification. Aeration has met with some success, although it has rarely proved to be a panacea. During heavy rain, London's sewage storm pipes overflow into the River Thames , sending dissolved oxygen levels plummeting and threatening

2494-471: The species it supports. Two dedicated McTay Marine vessels, oxygenation barges Thames Bubbler and Thames Vitality are used to replenish oxygen levels, as part of an ongoing battle to clean up the river, which now supports 115 species of fish and hundreds more invertebrates, plants and birds. The dissolved oxygen concentration within Cardiff Bay are maintained at or above 5 mg/L. Compressed air

2552-417: The tractor motion. This is an advantage when the load driven by the PTO requires the tractor motion to slow or stop running to allow the PTO driven equipment to catch up. It also allows operations where the tractor remains parked, such as silo-filling or unloading a manure spreader to a pile or lagoon rather than across a field. In 1945, Cockshutt Farm Equipment Ltd of Brantford , Ontario, Canada, introduced

2610-541: The tractor to power certain low-power-demand implements like hay rakes or tedders using lower engine speeds to maintain the revolutions per minute needed, using less fuel and placing less stress on the engine – thereby improving efficiency and reducing costs. The first industry standard for PTO design was adopted by ASAE (the American Society of Agricultural Engineers ) in April 1927. The PTO rotational speed

2668-488: The tractor's cab; when standing behind the tractor and looking directly at the shaft, it turns clockwise. A 10-spline type was used with some early equipment such as the 1948 Land Rover . A six-spline adapter was usually supplied. It is customary for agricultural machines manufacturers to provide the nominal PTO power specification, an indication of the available instantaneous power at the shaft. Newer tractors may come equipped with 540/540E and/or 1000/1000E options that allow

2726-530: The transmission. Care is also needed to ensure that the physical space around the transmission allows for installation of the PTO. The PTO is engaged and disengaged using the main transmission clutch and a remote control mechanism which operates on the PTO itself. Typically, an air valve is used to engage the PTO, but a mechanical linkage, electric or hydraulic mechanism are also options. Most Unimogs come with front and/or rear PTOs and hydraulics as well as three point hitch systems. Units will be rated according to

2784-454: The truck's power take-off shaft", District Attorney Joseph Early Jr. said in a statement. Despite much work to reduce the frequency and severity of agricultural injuries, these events still occur. Some implements employ light free-spinning protective plastic guards to enshroud the PTO shaft; these are mandatory in some countries. In the UK, Health and Safety Executive guidance is contained in

2842-468: The unit are a number of diffusers. These diffusers come in the shape of discs, plates, tubes or hoses constructed from glass-bonded silica, porous ceramic plastic, PVC or perforated membranes made from EPDM (ethylene propylene diene Monomer) rubber . Air pumped through the diffuser membranes is released into the water. These bubbles are known as fine bubbles . The EPA defines a fine bubble as anything smaller than 2mm in diameter. This type of aeration has

2900-489: The water and allowing oxygen transfer through air-water contact. As each new section of water is churned, it absorbs oxygen from the air and then, upon its return to the water, restores it to the water. In this regard paddlewheel aeration works very similarly to floating surface aerators. Subsurface aeration seeks to release bubbles at the bottom of the water body and allow them to rise by the force of buoyancy. Diffused aeration systems utilize bubbles to aerate as well as mix

2958-454: The water to the fountain can be a safety hazard. Floating surface aerators work in a similar manner to fountains, but they do not offer the same aesthetic appearance. They extract water from the top 1–2 feet of the water body and utilize air-water contact to transfer oxygen. Instead of propelling water into the air, they disrupt the water at the water surface. Floating surface aerators are also powered by on-shore electricity. The effectiveness of

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3016-469: The water. Water displacement from the expulsion of bubbles will cause a mixing action to occur, and the contact between the water and the bubble will result in an oxygen transfer. Subsurface aeration can be accomplished by the use of jet aerators , which aspirate air, by means of the Venturi principle, and inject the air into the liquid. Coarse bubble aeration is a type of subsurface aeration wherein air

3074-451: The wheel skid rather than turn, even if cleated . The concept of a shaft drive with easily connected and disconnected couplings, and flexibility for driving at changing angles (such as when an articulated tractor-and-trailer combination turns), was a goal to pursue. Experimental power take-offs were tried as early as 1878, and various homemade versions were constructed over the subsequent decades.   International Harvester Company (IHC)

3132-414: The work. For moving vehicles such as a traction engine or early tractor towing a farm implement , the implement could receive rotary power by taking it from one of its own wheels (whose turning was imparted by the towing) and distributing it via roller chains (to a sickle bar 's crank, for example), but such a transmission ceases if the vehicle stops traveling, and the workload's resistance tends to make

3190-467: Was first to market with a PTO on a production tractor, with its model 8-16, introduced in 1918. Edward A. Johnston, an IHC engineer, had been impressed by a homemade PTO that he saw in France about a decade before, improvised by a French farmer and mechanic surnamed Gougis. He and his IHC colleagues incorporated the idea into the 8-16, and designed a family of implements to take advantage of the feature. IHC

3248-455: Was in the tens of billions, and they circulated the entire Bay volume in a matter of days. Due to pollution, disease and over-harvesting their population is a fraction of historic levels. Water that was once clear for meters is now so turbid and sediment-ridden that a wader may lose sight of their feet before their knees are wet. Oxygen is normally supplied by submerged aquatic vegetation via photosynthesis but pollution and sediments have reduced

3306-414: Was not alone in the market for long, as within a year PTOs were appearing on other production tractors, such as some Case models. In 1920, IHC offered the PTO option on their 15-30 tractor, and it was the first PTO-equipped tractor to be submitted for a Nebraska tractor test . The PTO was a competitive advantage for IHC in the 1920s, and other companies eventually caught up with PTO implementation. Inside

3364-419: Was specified as 536 ± 10 rpm; the direction was clockwise. The speed was later changed to 540 rpm. Truck transmissions have one or more locations which allow for a PTO to be mounted. The PTO must be purchased separately and care is required to match the physical interface of the transmission with a compatible PTO. PTO suppliers will usually require details of the make, model and even serial number of

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