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Units plant machines and devices for measuring mechanical quantities

Electricity is measured in units of power called Watts, named to honor James Watt, the inventor of the steam engine. A Watt is the unit of electrical power equal to one ampere under the pressure of one volt. One Watt is a small amount of power. Some devices require only a few Watts to operate, and other devices require larger amounts. The power consumption of small devices is usually measured in Watts, and the power consumption of larger devices is measured in kilowatts kW , or 1, Watts.

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Multiple Choice Questions (MCQ) with Answers on Mechanical Measurement and Metrology

VIDEO ON THE TOPIC: Physical quantities: Its Units and Measurements, College Physics Online Course -

The basic layout of the three main types of milking machines are the same. Each has a pump to remove air from the vacuum pipeline, a vacuum regulator and a container to collect the milk that comes into the teatcup assembly during milking. The principle of machine milking is to extract milk from the cow by vacuum.

The machines are designed to apply a constant vacuum to the end of the teat to suck the milk out and convey it to a suitable container, and to give a periodic squeeze applied externally to the whole of the teat to maintain blood circulation. A milking machine installation consists of a pipework system linking various vessels and other components which together provide the flow paths for air and milk. The forces necessary to move air and milk through the system arise from the fact that it is maintained at a vacuum.

Thus it is atmospheric pressure which forces air, and intra-mammary milk pressure which forces milk, into the system and the combination of these forces causes flow. To be a continuous operation it is necessary to remove air and milk from the system at appropriate rates. Although milking machines have now developed into systems that show considerable diversity they have the same basic components.

The air is removed by a vacuum pump at a constant rate. In a bucket or direct-to-can machine milk is removed from the system by disconnecting the milk container; in milking pipeline and recorder machines the milk is removed by a milk pump or releaser. In the bucket or direct-to-can machine the milk enters the teatcups and travels through the short milk tubes to the claw where air is admitted and the milk and air travel along the long milk tube to the bucket or can. The milk remains in the bucket or can and the air separates to pass up the vacuum tube to the vacuum pipeline.

The pulsator which is usually fixed on the bucket lid admits air intermittently and this passes along the long pulse tube to the teatcup chambers. To control the vacuum at a predetermined level air is also admitted to the system through a vacuum regulator which is fitted on the vacuum pipeline near to the milking points.

When the milk from the claw is raised to a pipeline this can markedly reduce the vacuum at the teat because of the weight of milk in the long milk tube. The reduction in vacuum can be much reduced by bleeding air through a small hole in the clawpiece. In addition to the designed sources of air admission, air can be drawn into the teatcups past the teat and also when a milk container is changed or emptied. In a poorly maintained machine there may also be inward leakage of air at joints or points of damage.

To maintain the working vacuum the vacuum pump extracts the air admitted into the system by compressing it so that it can be discharged to atmosphere. There is no further air admission at this point when a motor driven releaser milk pump is used to empty the receiver.

Other types of releaser eg. Where air and milk are transported together the flow pattern becomes complex depending on various factors particularly the volume of air relative to milk or air:milk ratio.

Towards the end of milking when the milk flowrate has decreased to 0. The air:milk ratio becomes important where milk has to be elevated from the claw as in milk pipeline and recorder machines other than those with low level milk pipelines. Elevating a liquid, as distinct from a gas, involves a loss of potential energy and this is compensated for by a change of vacuum.

Thus elevating a column of milk in a vacuum system through 1 m height reduces the vacuum by about 10 kpa. Therefore if the vacuum at the top of the column is 51 kpa it will be only 41 kpa t the bottom. This vacuum drop is markedly reduced by the admixture of air.

If the air:milk ratio is the weight of milk in the column is halved and the vacuum drop becomes only 5 kpa; if it is the vacuum drop is only 1 kpa. Under vacuum liquids cannot flow against gravity ie. Where the tube contains air and milk the liquid forms plugs which are separated by pockets of air in the proportion determined by the air:milk ratio. It can be measured as pressure difference with a mercury manometer in mm Hg see diagram. The standard pressure is now kilopascals kPa with kPa equal to the pressure difference between atmospheric pressure and absolute vacuum.

Vacuum can be measured in a variety of units. The difference in height of the levels is supported by atmospheric pressure. In the past the most commonly used units have been inches, millimetres or centimetres of mercury in Hg, mmHg or cmHg. Units now adopted by the International Standards Organisation ISO for International Standards of milking machines for vacuum measurement are kilopascals kPa with zero 0 kPa being equal to atmospheric pressure and kPa absolute vacuum.

Equivalent relationships for values of vacuum levels are Equivalents for vacuum levels of 50 kPa and 44 kPa that are the most commonly used levels for milking cows:. Pulsator connects pulsation chamber to atmosphere, liner collapses, squeezes the teat duct and prevents milk flow. The principles of machine milking were established many years ago and the basic method described below, is used in virtually all commercial milking machines although in a minority some modifications are made.

The teatcup liner is the only equipment that comes into contact with the cows teats. The continuous vacuum within the liner causes the teat duct streak canal to open and the milk to flow because of the pressure difference between the milk in the teat and vacuum. To prevent damage or pain to the teat that would be caused by the continuous vacuum a system called pulsation is used. This makes the liners collapse on and below the teats about once each second massaging the teat and maintaining a more normal blood flow.

In each pulsation cycle milk does not flow from the teat when the collapsed liner squeezes the teat duct. Flow rates are also influenced by the mechanical properties of the milking machine. Flow rates decline at the end of milking and when flow ceases there is usually a small amount of milk trapped in the sinus of the udder which can be removed by pulling ownwards on the clawpiece and massaging the udder ie.

With modern designs of liner the quantity of strippings is small ie. The small amounts of milk that are left do not affect milk yield or the average chemical composition of the milk obtained or mastitis. The fluctuations in vacuum in the teatcup liner have important effects on mastitis and milk flow. There are two types. These occur when the teatcup liners slip or fall from the teats or air enters when milking units are changed carelessly.

Vacuum recovery is slow if there is inadequate vacuum pump capacity. The cyclic movements of the liner in each pulsation cycle increase and decrease the volume of the liner under the teat. When milk is flowing this can cause marked changes in vacuum below the teat.

This can be reduced by:. The main milking machine factor affecting milk flow rate is the liner vacuum. Raising vacuum levels gives faster milking but also increases strip yields and in practice a compromise level of about half atmospheric pressure is used ie.

The pulsation characteristics also affect flow. An increased pulsation frequency rate gives faster milking but because this greatly increases the air admission in the machine and therefore the required pump capacity it is usual to keep pulsation rates at 50—60 cycles of liner opening and closing per minute.

Because milk flow ceases in each pulsation cycle when the liner is collapsed on the teat, faster flow rates are obtained by using a wider pulsation ratio ie. For udder health reasons the ratios are usually not greater than The design of the liner can also affect the flow rate but modern liners tend to have similar flow properties.

The most important characteristic of the performance of a liner is the amount of strippings left at the end of milking which is mainly determined by the dimensions and hardness of the mouthpiece. Liner design is largely empirical and farmers determine the best liners for minimum strippings by trial and error. Although the teat cup liners are connected to a pipeline maintained at a constant vacuum level there can be considerable vacuum fluctuations in the liners, mainly due to the movements of the liner wall brought about by pulsation.

When the liner is opening and the milk is moving away from the teat along the short milk tubes the vacuum below the teat will increase markedly due to the increased volume of the liner and the kinetic energy of the milk in transit. The fluctuations are increased with adventitious air admission that occurs when liners slip on the teats or when machines are removed from adjacent cows udders irregular fluctuations.

These cyclic and irregular fluctuations generate impact forces which are important factors causing mastitis. Various methods have been used to reduce fluctuations to prevent them having deleterious effects.

The most important are the provision of adequate airbleed holes in the claw or short milk tubes to aid milk flow and prevent flooding in the liner. Also useful has been an increase in the internal diameter of short milk tubes eg. These can be reduced by other modifications. In some designs the basic system of machine milking has also been modified to give lower levels of vacuum at the start and end of milking when there is no milk flow or by the inclusion of a positive pressure phase in each pulsation cycle to give increased let down stimulation.

The function of the vacuum pump is to extract air from the pipeline system and in the majority of milking machines it is a rotary exhauster driven from either an electric motor or a stationary internal combustion engine, using pulleys and V-belts. A few vacuum pumps are direct shaft coupled; their speed is then motor speed and cannot be changed.

When operating with a vacuum at the pump inlet suitable for milking cows 50 kPa , the pumping capacity should be sufficient for the total number of milking units connected. This will range from 70 litres of air per minute per unit for installations with 20 units to 85 per litres per minute for the smaller plants with 5 units.

For each 0. The pump should be fitted with drive belt guards, an effective silencer and, for oil lubricated pumps, an oil separator. Also, a nonreturn valve should be fitted in the exhaust pipe to prevent reverse rotation of the vacuum pump when switching off at the end of milking. It should also have a float valve to shut off the vacuum in the event of it filling with liquid.

At a vacuum of 50 kPa ie. Vacuum regulator is an automatic valve fitted into the main vacuum pipeline near to the milking units that is designed to maintain the working vacuum level in the milking machine, despite the varying air usage during milking. It operates by admitting air into the pipeline when the vacuum increases above the predetermined level. The valve is held closed by a weight or spring until the vacuum in the system overcomes the closing force, allowing atmospheric pressure to open the valve.

Servo or power operated regulators, which usually have remote sensing, utilize a small intermediate pilot valve to actuate the main air inlet valve. These regulators sense pressure changes in the vacuum pipeline at a position where more stable conditions might be expected to exist. All vacuum regulators have an air filter to filter the incoming air. The vacuum gauge indicates the vacuum in the pipeline system. Its most important function is to indicate abnormal levels and fluctuations in vacuum, eg.

Universally the Bourdon type gauge is used. It should not be less than 75 mm in diameter, graduated at intervals of 2 kPa and be adjustable. Most gauges have dual graduations, kilopascals kPa and millimetres of mercury mmHg , and have lines on the dial indicating the working vacuum level. Pulsators are valves that cause the liners to open and close on the teat once each second ie. The pulsator is a simple valve that alternately admits air and vacuum into the pulsation chamber formed between the rubber liner and he shell.

This causes the liner to open and close during milking.

A measuring instrument is a device for measuring a physical quantity. In the physical sciences , quality assurance , and engineering , measurement is the activity of obtaining and comparing physical quantities of real-world objects and events.

Ansys measure rotation. All rights reserved. The difference drives the system. This technique extracts maximum common variance from all variables and puts them into a common score. Transient Structural MBD Measure rotation used Factor analysis is a technique that is used to reduce a large number of variables into fewer numbers of factors. Vorticity is a measure of the rotation of a fluid element as it moves in the flow field.

Measuring instrument

Vibration analysis helps you monitor and detect issues using vibration data. Read about vibration analysis methodology, tools and techniques, vibration analysis measurement methods, and more. Vibration analysis is defined as a process for measuring the vibration levels and frequencies of machinery and then using that information to analyze how healthy the machines and their components are. While the inner-workings and formulas used to calculate various forms of vibration can get complicated, it all starts with using an accelerometer to measure vibration.

List of electrical and electronic measuring equipment

Try Lucidchart. It's quick, easy, and completely free. They are typically created by engineers who are designing a manufacturing process for a physical plant. With the record they provide, changes can be planned safely and effectively using Management of Change MOC. They can also be useful in training workers and contractors.

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When deciding which machines to monitor, critical machines should be given priority over other machines. This is much the same as monitoring the health of people. It is inappropriate to closely monitor the health of perfectly healthy people, and then to forsake the monitoring of others who genuinely need it. The same applies when monitoring the condition of machines. In general, the following critical types of machines should be monitored on a regular basis in order to avoid unexpected and costly problems:. Before taking a vibration measurement, you need to attach a sensor that can detect vibration behavior to the machine that is being measured. Various types of vibration sensors are available, but a type called accelerometer is normally used as it offers advantages over other sensors. An accelerometer is a sensor that produces an electrical signal that is proportional to the acceleration of the vibrating component to which the accelerometer is attached. What is the acceleration of a vibrating component?

What is a LVDT?

The study, characterization, observation, and quantification of plant root growth and root systems Rhizometrics has been and remains an important area of research in all disciplines of plant science. In the horticultural industry, a large portion of the crops grown annually are grown in pot culture. Quantifying root growth has varied over the last several decades with each method of quantification changing in its reliability of measurement and variation among the results. Methods such as root drawings, pin boards, rhizotrons, and minirhizotrons initiated the aptitude to measure roots with field crops, and have been expanded to container-grown plants.

There is a lot of confusion out there about OEE Operational Equipment Effectiveness and about the words efficiency and effectiveness. Let us look at these things in an objective and clear manner. Is OEE just a nice-to-have?

What's New Offices. Barrier that allows for stock feeding but does not permit operator to reach the danger area. Barrier that moves according to the size of the stock entering point of operation. Guard is in place when machine is at rest and pushes away when stock enters the point of operation. Shuts off or disengages power and prevents machine start-up when guard is open. Should allow for inching of machine. Replacing the guard should not automatically restart the machine. Cords connected to operator's wrists and linked mechanically to the machine automatically withdraw the hands from the point of operation during the machine cycle. Must be inspected prior to each operator change or machine set-up. Wrists are connected by cords and secured to a fixed anchor point which limit operator's hands from reaching the point of operation at any time.

Anytime a piece of machinery is running, it is making vibrations. failures; Mechanical looseness; Misalignment; Resonance and natural frequencies up from a transducer (device that converts a physical quantity into an electrical signal) phase is a relative time difference between two signals measured in units of angle.

Multiple Choice Questions (MCQ) with Answers on Mechanical Measurement and Metrology

The basic layout of the three main types of milking machines are the same. Each has a pump to remove air from the vacuum pipeline, a vacuum regulator and a container to collect the milk that comes into the teatcup assembly during milking. The principle of machine milking is to extract milk from the cow by vacuum. The machines are designed to apply a constant vacuum to the end of the teat to suck the milk out and convey it to a suitable container, and to give a periodic squeeze applied externally to the whole of the teat to maintain blood circulation. A milking machine installation consists of a pipework system linking various vessels and other components which together provide the flow paths for air and milk.

Vibration Analysis Explained

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What are Piping & Instrumentation Diagrams

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Vibration Analysis Explained

From Wikipedia, the free encyclopedia. Below is the list of measuring instruments used in electrical and electronic work.

NCBI Bookshelf. Working safely with hazardous chemicals requires proper use of laboratory equipment. Maintenance and regular inspection of laboratory equipment are essential parts of this activity.

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