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52 Cards in this Set
- Front
- Back
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What is pump datum? |
Back (Definition) |
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Stall on a fan? |
This is generally caused by having a fan that is grossly oversized and is slowed right down to move a very small amount of air compared to what it would be able to move. |
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What is a pump? |
A pump is a device that is a creates a pressure difference in a fluid |
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What is the difference between a pump and a circulator? |
Pump is an open system and a circulator is a closed loop. Pumps are larger because there is no pump returning to the inlet as is the case with a corculator
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What are the 4 components of a pump |
а. an impeller b. casing (with a volute discharge) c. shaft (and supported bearings)land d. seal
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List the three parts of an impeller? |
Eye Vanes Disc |
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How does the volute change fluid velocity pressure into static pressure? |
It does this by forcing the water flow through an ever increasing cross sectional area of the volute channel. As the channel size increases the velocity pressure decreases and the static pressure increases |
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What are the 2 types of pump seals? |
Mechanical seals rely on the close tolerance of two very smooth mating surfaces to prevent liquid flow through the seal. (Never run dry, dont leak) Packed seals use compressed and wetted packing rings pressed against the pump shaft that minimize liquid flow through the seal. (Leak intentionally)
>>Never touch the seal face while installing it!«‹ >>Mechanical Seals do not weep liquid!«‹ |
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Do mechanical seals leak fluid? |
No Packed seal type weep |
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Where does the lantern ring get its lubrication from? |
The flushing tube takes some pumped liquid (from the pump outlet) to lantern ring that distributes the liquid into the seal packing rings where it cools and lubricates the seal packing. Then it leaves the pump and drains out of the pump and onto the floor (or wherever) |
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Pump Bearings and Lubrication? |
Waste packed bearings use a porous material like cotton to wick lubricating oil between a sleeve bearing and the pump shaft. This type of bearing must be periodically refilled with oil.
Pump oil in top and remove grease from bottom at the same rate by opening the zirk |
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How is "proper bearing greasing accomplished"? |
by removing the relief plug before adding new grease through the fitting. The relief plug Is replaced only when new grease is forced out of the relief plug orifice. |
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Is the pump running during hydrostatic processes |
No |
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Static Head?
Weight of water? |
• Which is the weight of the column of water from surface of the upper free liquid vessel to the surface of the free liquid in the lower liquid vessel. The weight of a column of water is 2.31 feet/psi. |
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Test question: How do we convert psi knowing pumping head and the specific gravity of any fluid? |
a. PSI=(Head x sg)/2.31) 1/2.31= 0.43 psi per foot is easier for some |
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What is the first pump law? |
(GPM(2) / GPM(1)) = (RPM(2) / RPM (1)) |
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What is the difference between total static head and static head? |
Total static head is difference between the liquid surfaces on each of the vats
Static head is measured from the the pump output to the highest point it lifts to… this does not include what come in front of the pump. the pump is halfway up a 10ft lift then static head is 5ft and total static head is 10ft |
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What is the more complicated equation for static head that uses static head? Not the 0.43 psi/ft |
Back (Definition) |
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What is pump law 2? |
Pressure and rotational speed H can be (psi) or (ft of head)
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What is pump law 3 Hp and rpm? |
Back (Definition) |
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What is Bernoulli law? |
Pt= P(velocity) + P (static)+losses + gravity |
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Pumps in parallel will increase… |
More flow. (GPM) Rpm will stay the same because there are 2 |
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Pumps in parallel will increase… |
More flow. (GPM) Rpm will stay the same because there are 2 |
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Pumps in series increase….. |
static pressure output |
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Why would you want a all bronze pump? Bronze fitted? |
All Bronze can move domestic water. Bronze fitted can move chemically treated |
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Explain this graph |
Solution: • Plot minimum requirements on Pump Performance Curve (Slide 45) Select the next highest pump curve (7") Plot the estimated operating characteristics at the 7" curve and 110 GPM • Observe next higher BHP line and mark it. Answer: • The proper impeller and motor size - (7" impeller and 2 BHP motor) The WHP required (WHP=Efficiency × BHP) - 68% × 2BHP= 1.36 WHP • Pump discharge pressure @80 USGPM (plot total head and convert to psi) • Discharge Head in PSI + Static - (52ft/2.31)+17.31 = 39.82 PSI •Pump discharge pressure @30 USGPM - (plot total head and convert to psi) • Discharge head in PSI + Static - (55ft/2.31) + 17.31 = 41.11 PSI |
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Explain this chart? |
Solution: • Plot intercept of 225 USGPM and 50ft of total pumping head. • Interpolate pump RPM between two curves • (((1550-1450)/2)×0.7)+1450= 1520 RPM Pump Speed (est) •Interpolate horse power at this RPM. • (((7.5 - 5)/2)x0.4)+5)=5.5 HP at 1520 RPM • Select required pump motor HP using HP interpolation. . Select next motor RPM curve higher (7.5 HP) • The Pump discharge pressure- • (50ft total pump head + 10ft static head)/2.31= 25.97 psi discharge pressure |
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18. List five common causes of pump cavitation? |
a. NPSHA < NPSHR b. inadequate pump fluid flow C. too great of suction lift head d. pumping a fluid that is too viscous (too cold) or e. pumping a fluid too near its boiling point |
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List the symptoms of an air-bound pump? |
a. reduced fluid delivery : b. quieter than normal operation c. warmer than normal casing (especially near the shaft, bearings and seals) d. Ultimately the pump impeller will seize against the casing and e. the bearings and seals will fail. |
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Where is the point of no pressure change? |
At the compression tank |
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Why are two pumps operated in parallel? |
Greater flow |
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Why are two pumps operated in parallel? |
Greater flow |
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Why use two pumps in series? |
Heater total head |
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23. List the four variables depicted on a pump? |
23. List the four variables depicted on a pump performance curve? Slide 46 a. Total Head b.Brake Horse Power C. Volume d. Efficiency |
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When should a pump suction valve be shut? |
Never |
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What type of pump is used with potable water? |
Bronze |
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What is pump datum? |
Back (Definition) |
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What is discharge head? |
Back (Definition) |
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What is pump datum? |
Back (Definition) |
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What is discharge head? |
Back (Definition) |
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What is suction lift? |
Lift on the inlet side of the pump Back |
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What is suction head? |
Back (Definition) |
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What is friction head? |
Back (Definition) |
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What is differential head? |
Back (Definition) |
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Test is hard. Study bronze pump, changed 60 to 50 hz, us gallon to lbs 8.33, lots of math with all the equations |
Yup. Study up. |
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What pump is good for donestic water supply? |
All bronze |
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What pump is good for donestic water supply? |
All bronze |
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How many imperial pounds in US gallons? |
8.33 US Gallons |
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What pump is good for donestic water supply? |
All bronze |
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How many imperial pounds in US gallons? |
8.33 US Gallons |
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The volute changes velocity into static? |
Yes |
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If a pump ( 220Vac, 60 Hz, 380 GPM, 40Ft head, 10 BHP, 1750 rpm) uses 50 hz What is the new BHP?
(Rpm changes because of 50hz) |
(Rpm2 / RPM 1) ^ 3 = (Hp 2 / Hp 1)
5.7 BHP
Just remember hz changes rpm |
