Honeywell MPR, ABP, and TBP Series Board Mount Pressure Sensors User Guide
- June 7, 2024
- Honeywell
Table of Contents
Liquid Level Height Sensing Using
Selected Honeywell Board Mount
Pressure Sensors: MPR, ABP, and
TBP Series
A Technical Note
INTRODUCTION
This technical note demonstrates how to calculate the liquid level height in an unpressurized or pressurized container by using a board-mounted pressure sensor to measure the hydrostatic pressure.
EQUATIONS AND CONSTANTS
The full equation for pressure liquid level height versus pressure is:
Liquid Level Height = Pressure Exerted/(Density * Gravitational Constant)
However, for most applications at lower altitudes the simplified equation may
be used:
Liquid Level Height = Pressure/Specific Gravity, or H = P/SG where:
H = Height, in inches, of the liquid being measured
P = Pressure, in inches of water (inH2O), of the liquid being measured
SG = Specific gravity constant of the liquid being measured (See Table 1.)
Table 1: Approximate Specific Gravity Constants of Common Liquids1
| Liquid | Specific Gravity Constant |
|---|---|
| Water at 4°C | 1 |
| Water at 20°C | 0.998 |
| Ethyl alcohol at 20°C | 0.789 |
| Isopropyl alcohol at 20°C | 0.785 |
| Seawater at 25°C | 1.028 |
FINDING LIQUID LEVEL HEIGHT
Using an unpressurized container
Using the equation H = P/SG, the two examples in Figure 1 show how different media at different pressures may have the same liquid level height. The pressure sensor shown is Honeywell’s ABP Series, enhanced accuracy, digital or analog output, compensated/amplified, basic board mount pressure sensor. The MPR Series is an I 2 C or SPI digital output sensor.
Figure 1. Two Examples of Finding Liquid Level Height Using an Unpressurized Container
Example 1:
Water at 4°C| Example 2:
Ethyl alcohol at 20°C
---|---
H = 8.5 inH2O/1.00| H = 6.7 inH2O/0.789
H = 8.5 in| H = 8.5 in
Example 1:
Example 2:
Using a pressurized container
Instead of using a single ported sensor, as was used in measuring the liquid level height in an unpressurized container, the pressure sensor used here needs to be a dual-ported, liquid media compatible (wet/wet) device. The sensor is mounted at the bottom of the container. This positioning gives a liquid-coupled measurement. Although a small air bubble may be present due to trapped air between the container and sensor, this method, for the most part, directly measures the pressure which indicates the height of the liquid.
Example: What is the liquid level height of a container where
P1 = 9.0 inH20, P2 = 0.5 inH20, and the liquid is water at 4°C?
Using the difference between P1 and P2 as P, the equation in Section 2.0
becomes: H = (P1 – P2)/SG:
H = (9.0 inH20 – 0.5 inH20)/1.00
H = 8.5 in
Figure 2. Pressurized Container
Due to
the relative unavailability of dual-ported sensors tolerant of liquid media on
both ports, two single-ported gage or absolute pressure sensors have
traditionally been used in this situation. This method not only carries the
cost penalty of having to buy two sensors instead of one but may also double
the measurement error. For this reason, ABP Series and TBP Series
differential sensors are preferred.
SOLVING FOR SENSOR PRESSURE RANGE WHEN THE CONTAINER HEIGHT IS KNOWN
Example: What is the required pressure range of a sensor if the maximum height
of the container is 25 inches, and the liquid is water at 4°C?
Solving for P, the equation in Section 2.0 becomes: P = H x SG:
P = 25 in x 1.00
P = 25 inH20
A 25 inH2O full-scale pressure sensor is used (1 psi ≈ 27.7 inH2O at 4°C),
such as the ABP Series liquid media capable sensor ABPANT001PGAA5 or MPR
Series MPRLS0001PG0000SAB as shown in Figure 3.
The ABPANT001PGAA5 sensor provides an analog output proportional to the applied pressure in the container, from 0.5 Vdc (no pressure applied) and 4.5 Vdc (1 psi applied). In this example, the MPRLS0001PG0000SAB the sensor provides an SPI digital output proportional to the applied pressure of approximately 9430370 counts at 16 inches of water from the 24 bit ASIC when the water level is at 16 in.
Figure 3. Known Container Height
REMOTE OR TOP MOUNTING
This method, as shown in Figure 4, allows the sensor to be remotely mounted
using tubing to make the connection between the bottom of the container and
the sensor. A single piece of tubing, or a piece of tubing connected to a
tube, is used to run from the bottom of the container to the sensor.
The advantage of this method is that the media has an air column between it
and the pressure sensor, helping to isolate the sensor from harsh media. A
possible concern is that if the tubing interface or sensor has even a small
amount of mechanical leakage, it can have a significant impact on accuracy,
which shows up as drift over time of the measurement.
Figure 4 . Remote or Top Mounting
USING A TBP SERIES UNAMPLIFIED SENSOR
A TBP Series, compensated/unamplified basic board mount pressure sensor with
the liquid media option, may be used to measure liquids that are compatible
with silicone. Figure 5 shows an example circuit that may be used to amplify
the output.
Figure 5. Example Output Amplification Circuit
Example: What is the required value of Rg if P = 27.8 inH2O maximum, the
sensor used is 1 psi, and the liquid is water at 4°C?
Equations used:
Rg = 100000/(Gain-1)
Gain = Span/Signal
To account for part-to-part sensor and amplifier offset variation, use a 100
kOhm potentiometer to calibrate Vout:
Vout = 0.5 Vdc (no pressure applied)
Resulting amplifier output:
P at 0 inH2O = 0.5 Vdc
P at 27.8 inH2O = 4.5 Vdc
Span = 4.5 Vdc – 0.5 Vdc
Span = 4 Vdc
TBPDANS001PGUCV full scale output = 1.5
mV/V, or 7.5 mV when using a 5 Vdc supply:
Gain = 4 Vdc/0.0075 Vdc
Gain = 533
Rg = 100000 Ohm/(533 – 1)
Rg = 100000 Ohm/532
Rg = 188.0 Ohm
EVALUATION TOOLS
SEK002 Sensor Evaluation Kit (See Figure 6)
The MPR Series and digital versions of the ABP Series may be used in
conjunction with the SEK002 Evaluation Kit (purchased from Honeywell
authorized distributors). The SEK002 allows the user to obtain sensor
readings without needing to develop any code.
The SEK002 is plugged in as a shield board to an Arduino™ Uno Rev3
Microcontroller Board. Honeywell evaluation software downloaded to the user’s
PC controls the Arduino Uno Rev3 to take sensor readings that are then
displayed on the PC’s screen.
Figure 6. SEK002 Sensor Evaluation Kit (Shown with ABP Series Sensor and Arduino™ Uno Rev3)
MPR Series sensor on breakout board (See Figure 7)
Selected MPR Series sensors (catalog listing contains a “B” suffix) are available mounted on a breakout board which allows easier connection to the SEK002 Sensor Evaluation Kit.
Figure 7 . MPR Series Breakout Board
Warranty/Remedy
Honeywell warrants goods of its manufacture as being free of defective
materials and faulty workmanship during the applicable warranty period.
Honeywell’s standard product warranty applies unless agreed to otherwise by
Honeywell in writing; please refer to your order acknowledgment or consult
your local sales office for specific warranty details. If warranted goods are
returned to Honeywell during the period of coverage, Honeywell will repair or
replace, at its option, without charge those items that Honeywell, in its sole
discretion, finds defective.
The foregoing is the buyer’s sole remedy and is in lieu of all other
warranties, expressed or implied, including those of merchantability and
fitness for a particular purpose. In no event shall Honeywell be liable for
consequential, special, or indirect damages.
While Honeywell may provide application assistance personally, through our
literature and the Honeywell website, it is the buyer’s sole responsibility
to determine the suitability of the product in the application.
Specifications may change without notice. The information we supply is
believed to be accurate and reliable as of this writing. However, Honeywell
assumes no responsibility for its use.
For more information
Honeywell Advanced Sensing Technologies services its customers through a
worldwide network of sales offices and distributors. For application
assistance, current specifications, pricing or the nearest Authorized
Distributor, visit our website or call:
Asia Pacific Europe
USA/Canada| +65 6355-2828
+44 (0) 1698 481481
+1-800-537-6945| Arduino is a trademark
or registered
trademark of Arduino, LLC in
the United States and/or other countries.
---|---|---
Honeywell Advanced Sensing Technologies
830 East Arapaho Road
Richardson, TX 75081
sps.honeywell.com/ast
008317-3-EN | 3 | 05/21
© 2021 Honeywell International Inc.
References
Read User Manual Online (PDF format)
Read User Manual Online (PDF format) >>