Mechanical Engineering

Surge is defined as the operating point at which the compressor peak head capability and minimum flow limit are reached. The compressor loses the ability to maintain the peak head when surge occurs and the entire system becomes unstable. Under normal conditions, the compressor operates to the right of the surge line. However, as fluctuations in flow rate occur, or under startup / emergency shutdown, the operating point will move towards the surge line because flow is reduced. If conditions are such that the operating point approaches the surge line, the impeller and diffuser begin to operate in stall and flow recirculation occurs. The flow separation will eventually cause a decrease in the discharge pressure and flow from suction to discharge will resume. This is defined as the surge cycle of the compressor.
The surge cycle will repeat itself unless control systems are installed or operational changes are made to bring the compressor out of the surge cycle. The surge cycle may result in a small or large flow reversal period depending on the discharge gas volume and the pressure ratio. Chronic surge is characterized by intermittent periods of small flow reversal that may not cause severe damage to the machine. Acute surge is more pronounced, usually due to a rapid transition across the surge line. Any surge event can cause severe damage to the thrust bearings, seals, and the impeller.

simple machine

friction is an important force to have in life because friction helps objects that move or roll stop. Like brakes on a car, when you push down on the brakes the friction is there when the wheels stop,and the car will stop to.

in the cupboard with Michael Jackson

From the Hooke law, stress s is proportional to strain e; s = Ee where E is elastic modulus of the material; the stress is the bending stress which varies from plus on one surface to minus on the opposite surface.

P=rho*g*h

P= pressure

rho= density = 1000 kg/m^3 at about 20C

g= gravitational constant on earth at sea level = 9.81 m/s^2

h= height

P=1 bar=1x10^5 Pascals = 1x10^5 N/m^2 (based on the definition of the Pascal unit)

since by definition 1 Newton= 1 kg*m/s^2

1x10^5 N/m^2= 1x10^5 kg*m^2/(m^3*s)= 1x10^5 kg/(m^2*s)

1x10^5 kg/(m^2*s) = 1000 kg/m^3 *9.81m/s^2 * h

solving for h yields:

h= 1x10^5/(1000*9.81)= 10.19367 meters

This value might vary slightly due to the affect of temperature on the density of water.

35 to 70

It depends on the mix of concrete you are using. A basic 1-2-3 mix is 5 1/2 cubic feet of portland cement (a wheelbarrow, depending on its size, holds 1/2 to 1 cubic feet), 11 cubic feet of sand, and 16 1/2 cubic feet of stone (called aggregate) from 1/2 to 1 inch in size each. To this is added about 12-15 gallons of water.(1 1/2 to 2 cu.ft.). This will make just a little less than 1 cubic meter of concrete.

A weaker mix for basic work not needing structural strength a 1-2-3 mix of 1 part stone, 2 parts cement and 3 parts sand can be used, this would require a bit less than 1 part water.

A stronger mix of 1 part cement, 1 1/2 parts sand and 3 parts stone with about 1/2 part water is good for heavy duty concrete work. Stone will increase the strength of concrete and sand will weaken it. Using too much or too little water in the mix will weaken it as well. Additionally, concrete with too much water or too little cement tends to shrink and crack as it sets. The amount of water to use is mainly dependent on the cement in the mix. There should be at least half as much cement as sand in any mixture. The amount of stone to use should be between 1/4 and 3/4 of the total mixture. Grouts and mortars use no stone and may add limestone as an additional binder. These should not be used for structural concrete, but can be used for foundation pointing, bolt anchoring or mortaring brickwork.

The application of engineering knowledge to the development of medical products. The engineering disciplines involved range from the traditional engineering fields to software and genetic engineering. The field is broken up into a number of specialty areas as varied as the biological and engineering fields from which they spring.

Used in power generation. When steam turbine is on-line the Main Steam Stop Valve is fully open. When offline it is closed. Steam to turbine is controlled thru control valves after Main Steam Stop Valve

it is extruded through a mold. metal pipe is poured semi molten through a mold and forced out the other side. plastic is molten and forced thru a mold as well. there used to be a play-doh machine that would make a play-doh tube. then you could see how it's done.

hammer swer driver and some c-4

I'm trying to find that out too..

its really hard to find/.....

Pipe is identified by NB and thickness is defined by Schedule whereas Tube is

identified by OD.

For more detail about piping click here : http://pipingguide.blogspot.com/

An electric generator converts mechanical energy to electric energy while a motor converts electric energy to mechanical. A generator can actually act as a motor if it losses whatever is making it spin (called "motoring"), which is usually a very bad thing. Motors may be used as generators as well, depending on their design.

This is a tool that is used to measure the pitch diameter of a screw. This tool looks like a standard micrometer except that the anvils are specially configured to reach into the screw thread groove and touch the pitch diameter of the screw thread. The screw thread micrometer does not measure any other aspect of the screw thread. It does not measure the: pitch; threads-per-inch; major diameter; minor diameter; flank angles; lead; helix angle.

The modulus of elasticity is a property specific to a given material and in practice is derived through laboratory testing.

The modulus of elasticity is defined as stress/strain. One would have to apply a force uniformly over a known cross section of a material and monitor the strain utilising strain gauges. When the results are plotted you will notice that you get elastic behaviour up to a point of yield (this is known as the yield stress in normal carbon steels, however in stainless steel where the yield point is not as defined, we normally accept it to be the 0.2% strain) and the material should behave linearly in this area. If you take the gradient of the stress/strain, this will be your Elastic modulus.

Please note that the plotted curve will begin to flatten off roughly at the 0.2% strain line and this is due to the fact that the material has yielded. even after this point the material will not fail but will act 'plastically' up to a point where the material fractures which we call the ultimate stress.

A window air conditioner is designed to accommodate the compact space of a window frame. It has compressor unit, expansion valve, cold and hot coil, a filter, a control unit, thermostat, a set of fans and refrigerants also known as freons.

The units compressor compresses the refrigerant. It turns into a hot, high pressure gas that goes through a series of coils. This process dissipates the heat, and the refrigerant condenses into liquid form. In this phase, it runs through an expansion valve, evaporating and becoming a cooled low-pressure gas. Now it goes through another series of coils, absorbing heat and causing air to become cool. A window unit has fans to blow air over both sets of coils. The helps them retain heat to outside air and coolness to the indoors.

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Not a lot. A fire fighting pump found on most fire engines is the centrifugal type. Other than the amount of water it may flow and the number of discharges it can supply, there is no difference (although I'm not sure what "ordinary centrifugal pump" refers to unless it is a trash or sump pump). Centrifugal type pumps weren't always used in the fire service, but they are the standard now because they can spin (they can pump or maintain pressure) even when there is no water actually flowing.

The advantage of a first class lever is that by using less input force, you get more output force. Teehee!

In simple terms its a Joule

yes

Suction lift is only negative. Suction head is positive or negative.

Suction head is the distance between the surface of the liquid being pumped and the centerline of the pump. It can be positive or negative, and it can be affected by pressure or vacuum on the surface of the fluid. A negative suction head is also called suction lift.

Example 1: A D/A under 15 psig is set 20 feet above the feed pump the effective suction head is 54 feet. (15 psig is equivalent to 34 feet of water).

Example 2: A Condenser hotwell under 28 inches of vacuum (Hg) is set 16 feet above the suction of a propeller pump. The effective suction head (lift) is -15 feet.* (28"Hg = - 31 feet of water)

Example 3: A sump pump is set 4 feet below the surface of the well. The effective suction head is 4 feet.

*Note: Suction lift is only effective to a maximum of 21 feet, and 15 feet for hot water depending on temperature and pump slip.

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