An Elevating Experience with the B1100-1

Introduction

The B1100-1 Barometric Pressure USB Data Logger is capable of measuring minute changes in pressure. We thought the simplest way to collect pressure change data would be to take the USB Barometer to different altitudes, which would affect the atmospheric pressure on the USB Barometer. To test its data collecting abilities, we sent one of our test engineers to a tower in Florida to see how much pressure changed by riding the elevator up to the top.

Objective

This simple experiment demonstrated that valuable performance information regarding elevators and freight lifts is easily collected using the B1100-1 Barometric Pressure USB Data Logger.

Test Setup

Just turn the B1100-1 Barometer on and stick it in a pocket. Then all you need is a working elevator, escalator, or, if you're feeling energetic, some stairs.

Default B1100-1 Settings:

Test Procedure

Our test engineer, with USB Barometer in pocket, went up the elevator at around 9:30 AM. He then came back down the elevator at 11:00 AM to go to lunch. He returned from lunch at 1:00 PM, and went back up the elevator. At 3:00 PM, he went down the elevator to go home.

Results

When we looked at the USB Barometer data in the XLR8R program, we got the following graph:

Pressure versus Time
Barometric Pressure versus Time During Elevator Rides

We then copied the data into Excel to calculate absolute altitude using the following formula:

Altitude equation

We used the average barometric pressure for the city where the tower was for p0. The average sea-level pressure was 101638.6 Pa according to www.wunderground.com on the day our test engineer rode the elevator. As the tower was on the beach next to the ocean, the absolute altitudes are also fairly close to the altitudes from the ground. The graph for that data looked like this:

Altitude versus Time
Calculated Altitude

Discussion

One can see by looking at the graphs exactly when our test subject went up and down the elevator. In the graph that shows pressure, the points of time when the pressure reading is low are when the test subject was at the top story of the tower he was in. When the pressure reading is high, the test subject was on the ground. The sharp changes in pressure represent the elevator rides he took.

Looking at the altitude graph, it seems as though the tower our test subject was working in got taller while he was at lunch. This is due to the changing barometric pressure over the course of the day. To get a more thorough understanding of the pressure changes, we went back to www.wunderground.com to see the hourly changes in barometric pressure.

Using the hourly barometric pressure readings, we constructed this table showing the given barometric pressure at sea level, the measured pressure from the USB Barometer, and the calculated absolute altitude.

Time

Barometric Pressure (Pa)

Measured Pressure (Pa)

Altitude (m)

7:55

101720

101,543

14.7

8:55

101780

101,591

15.7

9:55

101720

100,594

93.8

10:55

101700

100,520

98.3

11:55

101650

101,494

13.0

12:55

101600

101,448

12.6

1:55

101510

100,406

92.2

2:56

101510

100,408

92.0

3:57

101480

101,288

16.0

The altitudes given in this table are much more precise than those shown in the graph using only the day's average barometric pressure. The height of the room of the tower is clearly near 95 meters above sea level, whereas the ground the test subject walked or drove along was around 15 meters above sea level. Therefore, the room our subject was in is approximately 80 meters off the ground.

The following is a graph showing the initial rise of the elevator at altitudes relative to a person standing on the ground.

Ascent Rate
Calculated Rise Rate of Elevator

We can also determine the velocity at which the elevator rises. The rate equation, Equation 2, will give us the average velocity of a certain time frame. Using the same time frame as shown in the graph above we found that the average velocity of the rising elevator is 18.4 m/min. To find more precise velocities, all one would have to do is use the same equation over smaller time intervals.

A more accurate way to find the average velocity of the elevator is to use the slope of a best fit line and use that as the average velocity. Using a best fit line provides a more accurate description of how the elevator moves using the time between the initial and final altitude. In this case we find an average velocity of 0.3211 m/s or 19.2 m/min.

Conclusion

The B1100-1 USB Barometer collects easily understandable and accurate pressure readings that could be used to measure barometric pressure changes due to weather or altitude. The USB Barometer can then be used to calculate different measurements such as altitude and vertical velocity.