1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
nevsk [136]
3 years ago
13

A vacuum pump is used to drain a basement of 20 °C water (with a density of 998 kg/m3 ). The vapor pressure of water at this tem

perature is 2.34 kPa (abs). Atmospheric pressure is 100 kPa (abs). What is the maximum height that the pump can be placed above the water and still drain the basement?
Engineering
1 answer:
lord [1]3 years ago
8 0

Answer:

The maximum theoretical height that the pump can be placed above liquid level is \Delta h=9.975\,m

Explanation:

To pump the water, we need to avoid cavitation. Cavitation is a phenomenon in which liquid experiences a phase transition into the vapour phase because pressure drops below the liquid's vapour pressure at that temperature.  As a liquid is pumped upwards, it's pressure drops. to see why, let's look at Bernoulli's equation:

\frac{\Delta P}{\rho}+g\, \Delta h +\frac{1}{2}  \Delta v^2 =0

(\rho stands here for density, h for height)

Now, we are assuming that there aren't friction losses here. If we assume further that the fluid is pumped out at a very small rate, the velocity term would be negligible, and we get:

\frac{\Delta P}{\rho}+g\, \Delta h  =0

\Delta P= -g\, \rho\, \Delta h

This means that pressure drop is proportional to the suction lift's height.

We want the pressure drop to be small enough for the fluid's pressure to be always above vapour pressure, in the extreme the fluid's pressure will be almost equal to vapour pressure.

That means:

\Delta P = 2.34\,kPa- 100 \,kPa = -97.66 \, kPa\\

We insert that into our last equation and get:

\frac{ \Delta P}{ -g\, \rho\,}= \Delta h\\\Delta h=\frac{97.66 \, kPa}{998 kg/m^3 \, \, 9.81 m/s^2} \\\Delta h=9.975\,m

And that is the absolute highest height that the pump could bear. This, assuming that there isn't friction on the suction pipe's walls, in reality the height might be much less, depending on the system's pipes and pump.

You might be interested in
A cylindrical tank is required to contain a gage pressure 520 kPa . The tank is to be made of A516 grade 60 steel with a maximum
enot [183]

Answer:

t= 4.5 mm

Explanation:

Given that

P = 520 KPa ( gauge)

Maximum allowable normal stress ,σ= 150

d= 2.6 m

Wall thickness = t

The normal stress for pressure vessel given as

\sigma=\dfrac{Pd}{2t}               ( hoop stress)

We always take maximum stress for safe design.

\sigma=\dfrac{Pd}{2t}

Now by putting the values

150\times 1000=\dfrac{520\times 2.6}{2t}

t= 4.5 mm

So the minimum thickness, t, of the wall is 4.5 mm

4 0
3 years ago
How does warming up the tires on a car increase grip with the pavement?
ICE Princess25 [194]

Answer:

because burning rubber increases the grip power

8 0
2 years ago
Can u say what’s this
tatuchka [14]

Answer:

particles of a solid object packed together

7 0
2 years ago
Read 2 more answers
What oil specification is used to express the thickness (viscosity) of the oil?​
Marianna [84]

Answer:

Viscosity is notated using the common classification “XW-XX”. The number preceding the “W” (winter) rates the oil's flow (viscosity) at zero degrees Fahrenheit (-17.8 degrees Celsius). The lower the number, the less the oil thickens in cold weather.

7 0
2 years ago
Responding to the campaign of 4 classes, 7A, 7B, 7C, 7D contributed the amount of support proportional to the numbers 8,6;7;5 kn
Zolol [24]

Writing life on my fantasy planet

8 0
2 years ago
Other questions:
  • What is the main role of matrix in composites! a)-to transfer stress to the other phases b)- to protect phases from environment
    7·1 answer
  • Refrigerant 134a enters a horizontal pipe operating at steady state at 40°C, 300 kPa, and a velocity of 25 m/s. At the exit, the
    11·1 answer
  • Reusable refrigerant containers under high-pressure must be hydrostatically tested how often?
    10·1 answer
  • 8. Which of the following is a characteristic of no-till farming?
    8·1 answer
  • Write a script (Program 2) to perform t he following matrix operations. Use output commands to clearly output each problem with
    15·1 answer
  • For a 20 ohm resistor R, the current i = 2 A. What is the voltage V? Submit your answer as a number without units. ​
    12·1 answer
  • Write what you already know about college majors. What are they? Can you think of any examples? When do you have to pick one? Ca
    10·2 answers
  • The difference in potential energy between an electron at the negative terminal and one at the positive terminal is called the _
    11·1 answer
  • Defination of rolling
    13·1 answer
  • What is the fastest plane in the world
    13·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!