How to Gauge the Performance of Centrifugal Pumps

How to Gauge the Performance of Centrifugal Pumps To use centrifugal pumps most efficiently, you must measure their performance, usually with gauges, the "eyes" inside a pump and within the system in which the pump is working. A pump service professional describes how gauges are employed to measuring pressure and vacuum. To use centrifugal pumps most efficiently, you must measure their performance. This can be done with gauges. They serve as "eyes" inside a pump and within the system in which the pump is working. Gauges measure pressure and vacuum, while providing answers to three questions that must be accurately answered and interpreted to solve performance problems: 1. What is the discharge gauge reading? 2. What is the suction gauge reading? 3. What is the speed? Gauging the differences There are many different types of gauges manufactured today, including diaphragm, bellows, spiral bourdon tube, diaphragm capsule, helical bourdon tube and C-type bourdon tube. Basically, however, any good quality gauge will do an acceptable job of measuring pressure and vacuum for you. Whenever possible, use gauges that are liquid filled because the needle tends to dampen out needle vibrations. Most gauges use the C-type bourdon tube, a hollow tube shaped like a "C." When pressure or vacuum-above or below the ambient atmospheric pressure-is applied inside the tube, the tube moves. This movement is connected through levers and gears to a hand or pointer. The pointer rotates around a face that has graduations on it (Figure 2). If the liquid you are dealing with has the same weight or specific gravity as water, use a gauge that reads in feet of water. However, if the liquid has specific gravities above or below water, use gauges that read in pounds per square inch (PSI) and inches of Mercury (Hg); then use the corresponding formula in Figure 1 to convert your readings into feet of water. Taking proper gauge readings Some centrifugal pumps have taps in the casing for both suction and discharge gauges. These ports, however, may be subject to clogging and natural casing turbulence. The preferred location for your gauge taps is in the piping, which is located immediately before and after the pump. If a discharge check valve is used, be sure the gauge is between the pump and the check valve. Install a compound gauge, which reads both vacuum and pressure, in the suction line as close to the pump as possible. Also, place the pressure gauge in the discharge pipe as close as possible to the pump. With the pump working, record the dynamic (in motion) gauge readings. If your centrifugal pump cycles on and off, record the gauge readings just before the pump shuts off. With the pump shut off, and the discharge check valve open, record the static discharge head. By holding the check valve, you will be exposing the gauge to the static column of water in the discharge piping. This will work only if you have a suction check valve or foot valve. After the pump has cycled again and is off, record the static suction lift on the vacuum gauge. Obtain an accurate "tached" speed of the pump shaft. Do not trust that a 1750 RPM motor will run at 1750. The speed could vary as much as 50 RPM. A Pump Troubleshooting Data Sheet (Figure 3) is provided along with this article to help you collect the proper information to begin to resolve any pumping problems. Described below is the significance of the electrical data to be gathered. Significance of electrical data Horsepower-When reporting a problem on a centrifugal pump, the customer needs to tell the repair technician the exact electric motor nameplate data in terms of horsepower. If the horsepower is less than what the pump actually requires, this could create a significant problem in the electric motor, and a performance problem with the pump itself. Speed-The speed is vital to know because the motor would have been specified for a pump at a particular speed. Voltage rating/enclosure-The voltage ratings on the nameplate, as well as the enclosure style, are all important to know as well. For instance, an open-drip-proof motor (ODP) has a different service factor than an explosion-proof motor. Service factor/full load amps-Another important piece of information for the service technician is the service factor, as expressed in full load amps. The technician will want to compare his amperage readings to those on the nameplate. Measured values Voltage to motor: Voltage is extremely important because of the possibility that the voltage may go over the rated voltage on the nameplate. For instance, if an electric motor reads 460 volts, but is actually receiving 470 volts via the electrical power source, the amperage readings would be expected to go up. Conversely, if the electrical motor is receiving 450 volts instead of 460, you would expect the amperage readings to go down. Drive data Whether the unit is close-coupled, flexible-coupled or v-belt driven may be important to the service technician, depending on the particular problem. What gauges will tell you Gauge readings will tell you many things to help you find the real source of the problem, including where your system is allowing the pump to perform on its curve (Figure 4). Here are some other tips as well: w When gauge readings are high, the total dynamic head is too high. w When gauge readings are low, the total dynamic head is too low. w When the vacuum gauge reads very high, you may have a plugged suction line. w The discharge gauge will show pressure before the pump comes to prime if you need an air release valve on self-priming pumps. w With a MAX VAC test, you will learn if the pump is pulling the proper vacuum on self-priming pumps. w When the gauge readings are low and vibrating, vortexing or entrained air is likely. Measuring performance The performance of centrifugal pumps can be seen by comparing the total dynamic head (TDH) to the flow at a given speed (Figure 5). TDH is the total resistance to flow that exists while the liquid is in motion. By using a gauge, both TDH and the speed of the flow can be measured. We can then find the flow rate at which the pump should be producing. TDH equals the dynamic suction gauge reading plus the dynamic discharge gauge reading. (If your suction reading is positive, then you must subtract this number from your discharge to get TDH.) Whatever gauge you use, it must be reliable and accurate. Bad gauge readings are worse than none at all because they will provide you with inaccurate and misleading information.

1. How do I put back the antenna on a '95 Mercedes s500?

Assuming nothing is wrong with the plastic track, all you should have to do is turn the radio off (so the ant. motor retracts the mast) and let the motor do the rest. But, since you still have 5" remaining when it retracts, check the condition of the mast. It sounds like you have a kink/bend in the mast so it can no longer retract fully. Another thing you may want to try is, assuming no damage do the mast, is to lubricate the mast itself. If it is dry, the motor has a much tougher time to retract and extend the mast.

2. How can one reverse the rotation of a DC motor?

You want to reverse direction of rotation of a DC motor, Then use a DPDT (Double Pole Double Throw) Switch, it's a very special type of switch it has three positions like - On/Off/OnWhile it's in centre your motor will be "off" and if it is positioned "on" then it will be rotating, same in case of the third "on" position it will be "on". In both different "on" postions the rotation of motor will be different depending upon how you connect The Wire of Motor and Battery to Your DPDT Switchas DPDT Switch can change direction of rotation of Motor, you can imagine it's applications, they are used for making robotic projects, RC projects, Toy Cars, Flying Drones and Much more.And if You Want to Control Speed of a DC Motor, Then You should buy one Motor Speed Controller, many types of Speed Controller are Available at Different Price Range Depending upon the Voltage and Current You are Supposed to Provide to Your Motor, For Example - 1-16V, 1-24V, or 1-30V Speed Controllers, and also for current rating, like - 3A, 5A, 10A, 16A, or 20A.

3. can you give an idea of how does a ship moves?

Most modern Cargo Ships and Liners are propelled by motor or steam. Steam Ships can be propelled two ways, either using a steam turbine to turn a propeller, or using a steam turbine to turn a generator, that feeds electricity to an electric motor that turns a propeller. Motor Vessels have internal combustion engines that either turn a propeller, or turn a generator that powers an electric motor to turn a propeller, the latter being classed as diesel electric. Nuclear Powered vessels use a reactor to create steam. The steam powers generators, feeding electricity to propulsion motors, and other systems throughout the ship. With one exeption, this type of ship is military. Another type of propulsion system more common in military vessels than the merchant fleet is Gas Turbine. This type of system is like the steam turbine, except combustion gasses instead of steam are used to turn it, like a jet engine. The turbines, or motors are coupled to reduction gears, kind of like a huge automobile transmission, to reduce the revolutions down to a manageable rate, and transfers the work to the propeller shaft. Once turning, the propeller creates thrust, moving the ship. Behind the propeller, is the rudder, which directs the thrust to steer the ship. When a ship has little or no headway or has sternway on, it has very poor control and does not steer well. In these situations Harbor tugs, and thrusters are required to safely manage the vessel, usually around the docks, and in harbors.. Once the Ship has a fair amount of headway on her, she gains directional stability and can be steered with her rudder alone. All of this is not taking into account wind and current. Wind affects the part of the ship that is out of the water, which is a vast amount of sail area. Current affects the part of the ship under the water, which can be over 50 ft deep. These two forces can increase your speed, slow you down, and affect your steering. Other factors affecting steerage and speed are the amount of water under the keel, and distance off a bank or shoal, which if not enough can cause the ship to shear, slow, or squat lower in the water.

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IGBT of Fuji Motor Electronic Equipment Technology
The IGBT technology of Fuji motor and electronic equipment technology has been commercialized since 1988 and has been supplied in the market so far. Figure 1-3 shows the development process and application technology of IGBT products from the first generation to the fifth generation. Epitaxial wafers are used in the first to third generation IGBT, and the characteristics are improved by optimizing life cycle control and refinement technology of IGBT. Then, the fourth and fifth generation products have achieved significant characteristic improvement through the transition from epitaxial wafer to FZ (floating zone) wafer. In this regard, the design policy of IGBT has changed greatly compared with the past.Firstly, the basic design idea of IGBT using epitaxial wafer (series products up to 600V of the third to fourth generation, called "breakdown type") is as follows. In order to realize the low-pass state voltage during IGBT conduction, a large number of carriers are injected from the collector side to fill the IGBT with high concentration carriers. In addition, the n-buffer layer specially set to maintain the high voltage forms a very thin n-layer, so as to realize the low-pass state voltage. In order to realize fast exchange, life cycle control technology aiming at the rapid disappearance of carriers filled in IGBT is also adopted (through these, low exchange loss (eoff) can also be realized). However, once the life cycle control technology is applied, even in the normal on state, due to the effect of this technology (the carrier transport efficiency decreases), there is a problem of increasing the on state voltage, which can be solved by further high carrier injection.In short, the basic design concept of IGBT using epitaxial wafer technology can be simply summarized as "high injection and low transmission efficiency". In contrast, IGBTs using FZ wafers (series after the fourth generation 1200V) adopt a reverse basic design to inhibit the injection of carriers from the collector side and improve the transmission efficiency by reducing the injection efficiency. In the above-mentioned design concept of IGBT using epitaxial wafer "high injection and low transmission efficiency", the carriers that are not easy to be injected are forcibly suppressed through the control of life cycle, which not only limits the improvement of characteristics, but also increases the standard deviation of on-state voltage characteristics through the control of life cycle, It is very disadvantageous to the large capacity required for parallel use with increasing requirements in recent years. The technology developed to overcome this problem is a new IGBT using FZ chip (NPT: non punch through (used from the fourth generation IGBT) / FS: field stop (used from the fifth generation IGBT) - IGBT). The IGBT does not adopt life cycle control. Its basic design idea is to control the impurity concentration of the collector (P layer), so as to inhibit the carrier injection efficiency. However, in order to realize the characteristics superior to the IGBT using epitaxial wafer, it is also required to realize more than one hundred for the 1200V high voltage resistant series IGBT μ M (the thickness of n-layer in NPT and fs-igbt using FZ wafer ≈ the thickness of chip (wafer). The thinner the thickness, the lower the on state voltage can be generated). In short, it is not too much to call the development of IGBT using FZ chip a challenge to chip thickness.Fuji electric and electronic equipment technology has solved these problems. Starting from the fourth generation 1200V series - IGBT, it has realized the commercialization of "s series" constructed by FZ chip NPT. In addition, 600V series technology with higher thickness requirements is further developed, and 600v-u2 series (fifth generation) is being commercialized. In addition, in 1200V series - the fifth generation "U Series", in order to improve the performance better than s series, NPT structure has been changed to FS structure.The so-called FS structure does not use the life cycle control technology. While following the basic design concept of "low injection and high transport efficiency" of carriers, an n buffer layer to maintain voltage is set on the FZ wafer, so as to realize the IGBT structure thinner than the NPT structure. Through this change, 1200v-u series realizes the low on state voltage characteristic better than s series, and completes its commercialization. In addition, this technology is also used in 1700V series high voltage withstand series, and is also starting to be commercialized.Figure 1-3 changes of Fuji motor electronic equipment IGBT application technologyIn addition, Fuji electric and electronic equipment technology is also refining the surface structure indispensable for the improvement of IGBT characteristics (IGBT is formed by multiple IGBT plates. Through refinement, the more plates, the more low on-state voltage can be realized). Up to the fourth generation products, the planar structure (the structure of planar IGBT) has been used to promote refinement, so as to improve the characteristics. However, starting from the fifth generation products - 1200 and 1700V series, the grooved IGBT technology slotted on the Si surface and constituting IGBT has broken the subtle technical barrier and achieved unprecedented characteristic improvement. Figure 1-4 shows the change of characteristic improvement of 1200V series.Figure 1-4 improvement of balance characteristics
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