Question 1

Measurement Types

Accepted Answer

The most common measurement types for pressure sensors include absolute pressure, gauge pressure, sealed gauge pressure, differential pressure, and combined pressure.

Question 2

Absolute:

Accepted Answer

Measures pressure relative to a hard vacuum. Typically, these devices contain a small vacuum chamber exposed on one side of the sensor, and the pressure to be measured is applied to the other side. At sea level, an absolute pressure sensor exposed to air will read 1 ATM or 14.7 psi.

Question 3

Gauge Pressure:

Accepted Answer

Measures pressure relative to local atmospheric pressure. One side of the sensor is exposed to the atmosphere (through a small hole in the housing), and the other side is exposed to the pressure to be measured. A gauge pressure sensor exposed to air will always read zero ATM or zero psi because the same pressure is applied to both sides of the sensor. This device must have a ventilation path to allow some atmosphere into the body.

Question 4

Sealed Gauge Pressure:

Accepted Answer

Measures pressure relative to a standard gauge pressure; there is no actual atmospheric reference. Typically, this device includes an absolute reference and electronically adds an offset to represent standard atmospheric pressure. This simulates instrument components that do not require an exhaust path and is typically used in high-pressure environments where atmospheric changes are less significant.

Question 5

Differential Pressure:

Accepted Answer

This device has two pressure ports and measures the difference between them. This can be used to measure small pressure differentials under high-pressure line pressures, such as filter monitoring. Adding a second port and considering line pressure would result in a large number of scenarios having to be considered when designating the device.

Question 6

Combined:

Accepted Answer

Measures both negative and positive gauge pressure. The combined pressure sensor provides a linear output signal from full vacuum to zero pressure and then to full-scale pressure.

Question 7

Output Signal

Accepted Answer

Generally, the electrical output of a pressure sensor changes linearly with the applied pressure. Common output types include:

Question 8

mV:

Accepted Answer

Typically, the mV signal comes directly from the sensor bridge, requiring only simple calibration electronics. The output will be proportional (ratio) to the supply voltage. The supply can be constant current or constant voltage. The commonly used simple passive compensation circuitry limits accuracy to some extent.

Question 9

0.5 to 4.5V Ratio:

Accepted Answer

This is common in automotive applications. The device is powered by a nominal 5V supply, and the output varies proportionally to the supply voltage within a specified range. Some diagnostic codes can be provided by controlling the output outside the range.

Question 10

Amplified 1-5V:

Accepted Answer

A variety of amplified signals can be provided, the most common being 1-5V. These devices typically include a voltage regulator, so the output does not vary with the supply voltage.

Question 11

4-20mA:

Accepted Answer

A common industry standard, requiring only two wires, its advantage is that the signal is not degraded by long wiring. The device draws 4mA at low voltage and 20mA at full scale. This can be monitored by measuring the voltage across a series resistor.

Question 12

Digital:

Accepted Answer

It can provide a variety of digital outputs, including CANBUS, I2C and SPI, URAT, OWI.

Gauge Pressure Temperature Compensated Sensor

WF100E-P

Positive Pressure

WF100E-N

Vacuum Type

WF100E-W

Positiver und unteren Druck

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