0
Mechanical Engineering
Mechanical Engineering is a branch of engineering that encompasses the generation and application of heat and mechanical power and the design, production, and use of machines and tools. Mechanical engineering involves application of the principles of dynamics, control, thermodynamics and heat transfer, fluid mechanics, strength of materials, materials science, electronics, and mathematics.
10,989 Questions
What is seat leakage test in safety valves?
Seat leakage is defined as leakage that is internal to a valve-between the inlet and outlet sides of the valve-when the valve is in its closed position. It is not limited to leakage across the valve seat, but also encompasses all leakage across the valve trim when the valve is in the closed position. Leakage across internal trim seals, such as piston rings, and across trim-to-body seals, such as gaskets, can be counted as seat leakage.
It is important to note that, while leakage through valve stem packing is of growing concern in the industry, governing industry standards address this type of leakage separately and do not consider it to be a form of seat leakage.
What does Tpa stand for tensile strength related studies?
If you are thinking TPa, that is terapascals, or 1 trillion pascals. It is used where truly massive pressures exist. For tensile strength, no material has a strength measured that high. Most materials are measured in MPa, or 1 million pascals.
The study of motions is dealt with in a branch of physics known as mechanical physics. It can be further classified into quantum and classical.
What are the problems with thermal switch?
If you have a problem with the thermal switch, your fans will not come on at temperatures that will switch the fans to on in order to cool down the engine temperature. If you have a problem with the switch (faulty, burnt out), the only way to fix it is to replace it.
Cycle of concentration in cooling tower?
Cooling Tower Cycles of Concentration As pure water is evaporated, minerals are left behind in the recirculating water. As evaporation continues, the water becomes more concentrated than the original make up water. This eventually can lead to saturated conditions. The term cycles of concentration compares the level of solids of the recirculating cooling tower to the level of solids of the original raw make up water. If the circulating water has four times the solids concentration than that of the make up water, then the cycles are 4. Bleed off is the process of removing a portion of concentrated recirculating water, which is obviously replaced with fresh make up water. By specifying a certain amount of bleed off we limit the cycles of concentration the system can operate at, thus controlling scale formation. Various treatments will let us operate at various cycles depending on the make up water analysis and heat loading of the tower. Bleed off is critical to a successful treatment program. The preferred method of bleed off control is with the use of automated bleed off control. This includes a contacting head water meter, dual timer, chemical pump and solenoid controlled bleed off line. A) Evaporation Loss: from a cooling tower (E) = .001 (Cr) (DT) where Cr = circulation rate in gallons per minute and D T = temperature differential between hot and cold water in °F. The evaporation rate amounts to 1% of the recirculation rate for every 10°F DT. B) Windage Loss: This is a relatively small amount of entrained water lost as fine droplets in the air discharge from a tower. Unlike evaporation which does not contain dissolved impurities windage carries these impurities with it and reduces dissolved solids in the circulating water. Typical values are 0.1% to 0.3% of the circulating rate for mechanical draft towers. C) Bleed off: In the evaporation process the non volatile impurities in the make up water are concentrated. To prevent excessive concentration some of the circulating water must be removed from the system. This is commonly referred to as bleed off or blowdown. The amount of bleed off can be determined from the following equations: % B (bleed off) + % (windage) = % E (evaporation loss) / ( cycles -1) D) Cycles: The previous equation added a new turn to the mix . CYCLES!!!!!!!! This is one of the most difficult terms to understand. I will now attempt to define cycles of concentration. The NACE defines it as: A measure of the degree to which dissolved solids are being concentrated in the circulating water. It is in effect the inverse of blowdown. As pure water is evaporated all of the solids are left behind so they concentrate in the cooling tower water. If we start out with fresh water the tower has one cycle of concentration. When all the fresh water is evaporated ( solids are still in the tower) the tower then refills itself with more fresh water and we have twice the solids in the tower. We now have two cycles of concentration. This process will proceed and scale will form at a certain point. We use bleed off to prevent the tower from reaching the point of scale formation. In an actual tower, this is an ongoing process with continuous addition of make up water and continuous bleed off. The allowable cycles of concentration will be determined by the laboratory. They are based on water analysis, heat transfer rate of the equipment, and feed equipment present. We normally use chloride to determine the number of cycles a tower is operating at. The following equation can be used for this calculation: Chlorides in tower water / Chlorides in make up water = Cycles of concentration For example, a tower operating at a 450 gallons per minute recirculating rate (Cr) , 5 cycles of concentration, 10° DT, and 0.1% windage loss: %B + .1% = 1% / (5-1) which is %B = .25% - .1% therefore %B = .15% of the circulating rate. %B = 0.15% ( 450 gallons/minute) which is 0.675 gallons of bleed off /minute. Total make up water requirements for the system are: Bleed off 0.675 gallons per minute
Evaporation 1% (450 gallons/minute) = 4.5 gallons/minute Windage 0.1% (450 gallons/minute) =.45 gallons/minute Total make up water = 5.625 gallons/minute Total make up water per hour is = 60 minutes/hr. ( 5.625 gallons per minute) = 337.5 gallons per hour. As you can see the higher the cycles the less make up water and blowdown are required. This is true to a certain point where additional cycles do not decrease the amount of make up water and blowdown as drastically. The following graph illustrates the point. As you can see at about 4.5 cycles the curve starts leveling off which indicates higher cycles will not effect the quantity of make up water drastically.
What do you mean by spindle in lathe machine?
The spindle of a lathe is a rotating hollow tube within, and protruding the head stock and to which a chuck, drive plate or facing plate attaches and rotates to enable machining.
It is housed within the head stock in bearings and has some gears around it which is driven by other gears which in turn is driven by an electrical motor.
What is the ANSI Z308.1-2009 standard?
This is the "Minimum Requirements for Workplace First Aid Kits". This addresses the minimal first aid needs for small worksites as determined by the American National Standards Institute. Before deciding to abide by this and only this, one would need to take into consideration the physical size and layout of the operation, number of employees, type of work being done and hazards present and augment accordingly.
What type of material used for cotter joint?
why what type of material is used?which are the manufacturing companies?what are its standard dimension?
These types of joints are used to connect the end of a rod or bar to a shaft. The end of the bar has a hole in it and it is called a lug. The hole carries a shaft. This shaft is locked in place by a smaller pin that passes through the side of the lug and partly or completely through the shaft itself. This locking pin is named a cotter, which sometimes is also applied to the whole joint.
The obvious example is on a bicycle where both pedal bars are separately locked by a cotter pin, on their common driving shaft having the sprocket wheel.
Steel is the most common material used for this application. There are no specific manufacturing companies who make only cotter pins, nor are there any dimensional standards by which they are designed.
What is static and dynamic load in axial fans?
In axial fans, static load refers to the pressure exerted by the air moving through the fan when it is not in motion, while dynamic load describes the forces acting on the fan during operation, including rotational forces and airflow-induced stress. Static load is primarily concerned with the fan's ability to maintain air pressure, whereas dynamic load takes into account factors like vibration, speed, and airflow changes that occur during operation. Together, these loads influence the fan's design and performance, ensuring it operates efficiently and reliably.
What is the difference between corrosion and rust?
Corrosion is the broad term for something that something is being broken down or eaten away due to chemical reaction. For example dis colorization of a painted object that has been in the sun. You can see some red cars turn pink in time if not take care of. Or i metal when you leave nickel in lemon juice above the water line will turn green and when you wipe it away it feels all rough and that is corrosion
Rust is a specific type of corrosion that consists of iron being reacting with water (or moist air) causing iron oxides
A fluid coupling is a hydrodynamic device used to transmit rotating mechanical power. It has been used in automobile transmissions as an alternative to a mechanical clutch. It also has widespread application in marine and industrial machine drives, where variable speed operation and/or controlled start-up without shock loading of the power transmission system is essential. They are also sometimes called a Fluid Flywheel.
Why holiday detector is called so?
Following the description of the pronunciation problem, it is helpful to understand this widely used quality control process.
Briefly, this process involves testing the integrity of a non-conductive surface such as painted coatings or plastic by attempting to pass an electric pulse between electrodes, each applied to either side of the surface. If any holes or gaps exist, then the electricity is able to complete a circuit sounding a warning, which alerts the operative to the existence of a fault. Hence the specialised term 'Zap Test' used in some industrial settings.
The word 'holiday' in this industrial or manufacturing connection might seem an unusual choice of word and most dictionaries only include the traditional and wider known uses. According to Chambers dictionary of etymology, the term, possibly recorded before the 1200's developed from the old English hālig dæg a religious term, literally meaning a 'Holy Day'. Another form was Hallowmas, apparently in use until the 16th century.
Searches of the BNC and Collins Cobuild Corpora didn't yield any industrial uses, so it required a manual search of the full and Shorter OEDs in the local libraries in Canterbury and Whitstable to find reliable sources of variants:
The OED lists the following examples (among many others) of the noun 'holiday' :
1. Holiday (n) A consecrated day; a religious festival.
2a ~ A day on which ordinary occupations ( of an individual or a community) are suspended; a day of exemption or cessation from work; a day of fasting, recreation or amusement.
2e a holiday Used euphemistically for imprisonment. e.g. 'a little holiday'.
~ colloquial: nautical: A spot carelessly left untreated in tarring or varnishing. 1785 Grosse Dict Vulg T s.v : 'A holiday is any part of a ship's bottom left uncovered in painting it.'
~ 1882 Holidays, parts left untouched in dusting 'Don't leave any holidays'.
It is in these latter examples that the idea of missing a piece of work or 'taking a holiday from' an area or section of work is conveyed.
Likewise, the Shorter OED 2002 Ed. describes the term in this context as being 'chiefly nautical - A patch or area unintentionally left in painting etc.
Similarly, According to PK Kemp (1976):
Holiday - a gap unintentionally left uncovered when painting or varnishing on board ship and applying equally to a ship herself or to her masts and spars. It is also a gap left, equally unintentionally in paying a deck seam with oakum and pitch.
http://www.hltmag.co.uk/jun09/less03.htm
What is the principle of propulsion?
It is create a difference in pressure artificially by exploding or burning a fuel inside a closed chamber and evacuating the pressure suitably
turbo blower is an equipment where a turbine is attached with the blower part. steam enters through the turbine inlet and expands through the blades and goes to the outlet which helps the turbine shafts to rotate. this turbine shaft is attached with the shaft of blower that makes the blower rotating.
A repeater connects two segments of your network cable. It retimes and regenerates the signals to proper amplitudes and sends them to the other segments. When talking about, Ethernet topology, you are probably talking about using a hub as a repeater. Repeaters require a small amount of time to regenerate the signal. This can cause a propagation delay which can affect network communication when there are several repeaters in a row. Many network architectures limit the number of repeaters that can be used in a row. Repeaters work only at the physical layer of the OSI network model.
DEFINITION - 1) In digital communication systems, a repeater is a device that receives a digital signal on an electromagnetic or optical transmission medium and regenerates the signal along the next leg of the medium. In electromagnetic media, repeaters overcome the attenuation caused by free-space electromagnetic-field divergence or cable loss. A series of repeaters make possible the extension of a signal over a distance.
Repeaters remove the unwanted noise in an incoming signal. Unlike an analog signal, the original digital signal, even if weak or distorted, can be clearly perceived and restored. With analog transmission, signals are restrengthened with amplifiers which unfortunately also amplify noise as well as information.
Because digital signals depend on the presence or absence of voltage, they tend to dissipate more quickly than analog signals and need more frequent repeating. Whereas analog signal amplifiers are spaced at 18,000 meter intervals, digital signal repeaters are typically placed at 2,000 to 6,000 meter intervals.
2) In a wireless communications system, a repeater consists of a radio receiver, an amplifier, a transmitter, an isolator, and two antennas. The transmitter produces a signal on a frequency that differs from the received signal. This so-called frequency offset is necessary to prevent the strong transmitted signal from disabling the receiver. The isolator provides additional protection in this respect. A repeater, when strategically located on top of a high building or a mountain, can greatly enhance the performance of a wireless network by allowing communications over distances much greater than would be possible without it.
3) In satellite wireless, a repeater (more frequently called a transponder) receives uplink signals and retransmits them, often on different frequencies, to destination locations.
4) In a cellular telephone system, a repeater is one of a group of transceivers in a geographic area that collectively serve a system user.
5) In a fiber optic network, a repeater consists of a photocell, an amplifier, and a light-emitting diode (LED) or infrared-emitting diode (IRED) for each light or IR signal that requires amplification. Fiber optic repeaters operate at power levels much lower than wireless repeaters, and are also much simpler and cheaper. However, their design requires careful attention to ensure that internal circuit noise is minimized.
6) Repeaters are commonly used by commercial and amateur radio operators to extend signals in the radio frequency range from one receiver to another. These consist of drop repeaters, similar to the cells in cellular radio, and hub repeaters, which receive and retransmit signals from and to a number of directions.
7) A bus repeater links one computer bus to a bus in another computer chassis, essentially chaining one computer to another.
A fillet weld is the joint of 2 pieces of material, usually at a 90 degree angle. see http://www.unified-eng.com/scitech/weld/fillet.html
What is tensile strength of tor steel?
- Rajuri Thermex TMT500 rebars have excellent bend properties due to the unique ductility (elongation values) obtained when using the German HSE Thermex Technology.
- Corrosion Resistance properties
Controlled water-cooling prevents the formation of coarse carbides, which has been cited as the main cause for the corrosive nature of common bar.
Another reason for better corrosion resistance is the absence of surface stresses caused by the cold twisting (and Torsteel) process.
- Weldability
Rajuri Thermex TMT500 rebars with carbon content less than 0.25% can be used for butt and other weld joints without reduction in strength at the weld joints.
- Fire Resistance
Unlike Torsteel and CTD Rebars, Thermex bars have high thermal stability. They are the preferred choice when elevated temperatures of 400-600 C may be encountered (Chimneys, fires).
- Earthquake Resistance
Thermex rebars have high fatigue resistance to Dynamic/ Seismic loads due to its higher ductility quality. This makes Thermex bars most suitable for use in earthquake prone areas.
- Formability
Due to very high elongation values and consistent properties through out the length of bar, Thermex rebars have excellent workability and bendability.
- Strain Ageing
Due to unique and scientific manufacturing process and chemical composition, Thermex rebars show no tendency of embrittlement either during welding or cold deformation of welded joints.
- Cost Effective
Thermex TMT rebars required 15-20% less usage than CTD bars for same work with cost 5% more than than CTD bars. This results in overall saving of 10-25%.
How can one control the process factors in order to get less maintenance?
make the proper lubrication schedule of all rotating equipment and availability's of all spare parts at proper time.
