What is the relationship between elevation and air pressure

Date: 2019-04-08 17:00:19

Many clients had the same question (or we can call it problem) after they bought the air bag OCA laminator (such as OM-K6edge, K5edge), the problem is that their machine keep pumping vacuum and never start the second step (Lamination step), sometimes they even can smell the burn from inside.

 

Why does this happen?

 

This is because of the "practical vacuum" did not reach  the "set vacuum". (This is only for the "vacuum" meter)

For example, the factory setting of the "Vacuum" meter is -98Kpa, if the maximum vacuum your machine only can reach -97Kpa, then your machine will always keep pumping vacuum unless it reach -98Kpa.  (That's why some clients said their machine never start the lamination step).

 

How to solve this problem?

 

1, When you get your machine, please check the blue seal ring on the lamination plate, make sure there has no any dust and space, because dust and space will make air leak, and your vacuum won't rise up.

2, After checked the blue seal ring, start your machine and write down the maximum vacuum your machine can reach.

3, If your maximum vacuum is more than -98Kpa, then your machine can work properly, but if your maximum less than -98kpa, then you will have the same problem above (pump always working and never start the second step)

4, After problem confirmed, then go to the "vacuum" meter and click the blue button (Note: only click, don't press the blue button over 2 seconds, because it will enter the advance setting model. And please DON'T set the vacuum meter in the advance model), go to "P_1" and set it less than your maximum vacuum, the difference normally is "-1", for example, if the maximum vacuum is -97.2, then please set the "P_1" to -96.2

 

Read the follow information to help you understand this easily.

 

Atmospheric pressure decreases exponentially with altitude. 
 

We are actually living near the bottom of an ocean of air.

At sea level, the weight of the air presses on us with a pressure of approximately 14.7 lbs/in2.  

At higher altitudes, less air means less weight and less pressure.  Pressure and density of air decreases with increasing elevation.  

Pressure varies smoothly from the earth's surface to the top of the mesosphere.  This table compiled by NASA gives a rough idea of air pressure at various altitudes (as a fraction of one atmosphere).
 

fraction
of 1 atm
average altitude
(m) (ft)
1 0 0
1/2 5,486.3 18,000
1/3 8,375.8 27,480
1/10 16,131.9 52,926
1/100 30,900.9 101,381
1/1000 48,467.2 159,013
1/10000 69,463.6 227,899
1/100000 96,281.6 283,076
Determining atmospheric pressure:

 
where:
p = atmospheric pressure
(measured in bars)
h = height (altitude)
p0 = is pressure at height h = 0 (surface pressure)
h0 = scale height 

This equation shows that the atmospheric pressure decays exponentially from its value at the surface of the body where the height h is equal to 0.

When h0 = h, the pressure has decreased to a value of e-1 times its value at the surface.
 

The surface pressure on Earth is approximately 1 bar, and the scale height of the atmosphere is approximately 7 kilometers.

Earth:   p0 = 1  and   h0 = 7

 Problems:

1.  Estimate the pressure at an altitude of 3 kilometers in Earth's atmosphere. 

Answer:   


2.  Estimate the pressure at an altitude equivalent to the height of Mount Everest (the highest point on Earth).  The altitude of Mount Everest is 8,848 meters.  (Change meters to kilometers.)

 

3.  Estimate the pressure at an altitude equivalent to the height of Mount Kilimanjaro, 5,895 meters.

 

4.  Estimate the pressure in the Earth's stratosphere at a height of 35 kilometers.  This pressure will be approximately equivalent to the pressure on Mars.

 

5.  Using your graphing calculator and the NASA table at the top, prepare a scatter plot of the altitude in kilometers (x-axis) and the air pressure (y-axis).  Find an exponential model equation for this data.

 

6.  Using your findings from questions 1, 2, 3 and 4, prepare a scatter plot of the altitude in kilometers and the air pressure.  Find an exponential model equation for this data.

 

7.  Compare the three equations you have obtained comparing altitude and air pressure.  What are the similarities?  What are the differences?  Explain.

 

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