Differential pressure sensors offer functionality beyond their primary purpose. Explore the unexpected measurements and applications that these multi-purpose sensors can be adapted to support.
Help Guides
Measurement and instrumentation help guides
Measuring flow rate of a liquid or gas using a dp sensor
An introduction to the dp flow method of using a differential pressure sensor for measuring the flow of liquids and gases.
Measuring density of a liquid using a dp sensor
This guide provides an overview of methods for measuring liquid density using differential pressure sensors in various tank configurations and conditions.
Measuring liquid level in a tank using a dp sensor
Differential pressure sensors can be used to measure liquid level in a tank. Here we will explain how a DP sensor is used to measure liquid level.
Measuring vacuum as a negative gauge pressure using a dp sensor
Learn how a differential pressure sensor (dp sensor) can be used to measure a partial vacuum as a negative pressure relative to local surrounding air pressure.
Measuring vacuum as an absolute range using a dp sensor
Find out how to use a differential pressure sensor (dp sensor) to measure a partial vacuum as a positive pressure relative to full vacuum.
Measuring barometric pressure using a dp sensor
Learn the method to convert a differential pressure (DP) sensor for barometric pressure measurement.
Measuring absolute pressure using a dp sensor
Learn the method to convert a differential pressure (DP) sensor for absolute pressure measurement.
Measuring gauge pressure using a dp sensor
Differential pressure sensors can double as gauge pressure sensors. Here we will explain how a DP sensor is used to measure gauge pressure.
How do you choose the correct pressure range for a pressure sensor
The pressure range is the most complicated and confusing specification parameters to define for a pressure sensor.
Can you have a minus 20 psi gauge vacuum measurement range
Is it possible to have a vacuum pressure measurement device with a -20 to +50 psi gauge pressure range, since I’ve never seen a pressure instrument with a range greater than -15 psi?
Stop sea water level or depth sensor failures due to pitting or corrosion
Despite sea water being one of the harshest environments where a liquid level sensing device can be used, it is surprisingly common to find sensors that have been installed and fail much sooner than expected, should never have been specified in the first place.
Checking the LHR error of a 0-5 Vdc output pressure transducer
We have a transducer which is rated for 0-2000 psi, and it outputs 0-5 Volts. The specification document states that the accuracy is a combined LHR of +/- 0.5 %FS, how would we check this?
Output signal orientation for a negative gauge pressure range
Since a negative pressure range works backwards to a positive gauge or an absolute pressure range, and that zero pressure corresponds to a full scale measurement, it has led to the use of both a forward and reverse output signal to measure suction or vacuum pressure in relation to ambient atmospheric air pressure.
Measuring negative pressure using a positive differential pressure range
How can you use a differential pressure measurement device to measure a negative pressure if it has been factory configured to measure a positive pressure range without making any adjustments to the electronics or the signal output?
Calculating required pressure range for fuel tank level measurement
Using a pressure measurement instrument to measure fuel level is very common, however most are scaled in bar or psi pressure ranges, and if they do happen to be scaled in level units, they are typically water level based, such as mH2O or ftH2O.
What does negative and positive gauge pressure mean
You may not be aware but nearly every pressure measurement device you are using has a positive or negative gauge reference.
Can you measure vacuum using a gauge pressure range
The most common type of pressure range for pressure measurement instrumentation is one which has a gauge reference. So if you want to measure vacuum pressure, it would be convenient to use a gauge pressure device which is the most widely available pressure range format.
What is the difference between vacuum and absolute pressure
Often you will see a measurement of vacuum pressure described as an absolute pressure reading, so is there any difference between the two?
Pressure Measurement
One of the most common measurements on any machine or process is pressure. Air, gas and liquids are used extensively on many types of machines as the medium used to operate moving parts.
Determine range of pressure gauge needed to measure force generated by hydraulic press
Work out what pressure gauge is needed based on the bore size of the cylinder and the maximum force generated by a press.
What are the advantages of using Wired Sensors instead of Wireless Sensors
This article explores the many advantages of wired sensors compared to wireless sensors in order to help you make a decision on whether to opt for a wireless sensor network over a wired sensor installation.
How do you measure the volume of a liquid using pressure
It is not possible to measure the volume directly, and unfortunately there is no such device as a volume sensor, however if you know the dimensions of the space filled with liquid, you can easily determine the volume.
How to create a list of specification parameters for a pressure sensor
Before purchasing a pressure sensor, there are a number of application questions you will need to answer to ensure it is fit for purpose
How to determine milk tank level and volume from pressure
How do I convert the pressure reading to quantity of milk at bottom temperature which varies approx 10 deg C
Why use 4-20mA and 3-15 psi rather than 0-20mA & 0-15psi
Why we mainly use 4-20 mA current and 3-15 psig pressure and not use from zero to 20 mA or 15 psig?
How do you measure flow rate with a dp cell
How do you use a dp cell measuring a span of 0-500 mmH2O with an o/p of 4-20 mA to control a flow rate of 0-1000 L/h for a flow meter range?
What is the difference between zero offset and zero drift?
Zero Offset relates to the zero setting tolerance during manufacture and Zero Drift relates to the expected maximum change in zero over time.
Choosing PVC, PUR, FEP and TPE cable types
When specifying the electrical connection for the DMP, DMK, LMP and LMK series of pressure/level transmitters you will need to choose from a selection of cable types.
Using Sealed Gauge Reference Pressure Sensing Devices
Sealed gauge or SG is a type of pressure reference typically used when a vented reference is not possible because of the type of sensing technology or the need to provide secondary containment overpressure protection.
Material Compatibility Resources
Incompatibility between a sensor and the media being measured is one of the major causes of premature failure.
What is the difference between sealed gauge and vented gauge reference?
Gauge reference pressure measuring devices read pressure relative to atmospheric pressure. This ensures that the pressure reading is nominally zero when the pressure on the device is released.
Liquid Level Measurement
Questions and answers about liquid level measurement
Simulating 8000 foot altitude with a pressure gauge
We are trying to simulate an environment of 8000 feet in altitude inside a cylinder. We are located in an area that is 200 feet above sea level.
Determining calibration error of Bourdon tube pressure gauge
How do you calculate maximum gauge error in pressure measurement with a bourdon gauge instrument?
Measuring the volume of liquid in a horizontal cylinder tank
We have a horizontal cylindrical type tank which has a diameter of 2 meter and a length of 7 meters. This tank is used for storage of chemicals.
How to get a 10 volt signal from a 4-20mA output pressure sensor
I have a 4 to 20mA pressure sensor, is there a way of converting the output to a 10 volt signal so I can use a voltage input data acquisition card?
What can cause random variation in pressure transducer output
I have a 10bar pressure transducer with a 4-20mA output which is showing a random variation across a span of 0.3mA (+/- 1.5mA) at a fixed pressure.
Problem with zero drift when installing submersible pressure sensor
I‘m having a problem zeroing a submersible pressure sensor. Before placing it in the water, the zero offset is trimmed on the indicator, and then it is submerged to full range depth of 10 metres. During the first few minutes we notice that the full scale reading drifts by about 10mm in the negative direction […]
Shunt resistor calibration explanation
What is the method of shunt calibration in relation to an indicator connected to a pressure transducer?
Difference between vented and non-vented water level measurement
A hydrostatic level probe typically uses pressure sensor to measure the water level. The main component of a pressure sensor is the sensing diaphragm which converts the difference in pressure between either side of the diaphragm into a measured signal. The front of the diaphragm measures the water level pressure (hydrostatic pressure) plus the barometric […]
Temperature Measurement
Questions and answers about temperature measurement
Determining water tank volume using hydrostatic pressure
Can a pressure measurement device be used to measure the volume in a rainwater harvesting tank?
What is difference between working, burst and over pressure
I have a confusion regarding the difference between the maximum working pressure, overpressure and burst pressure for pressure transmitters.
Converting non-vented depth readings & barometric pressure to true depth
I have level data from a non-vented transducer & barometric pressure data, how do I determine the true depth?
Process Connections
Find answers to questions about process connections used to install measurement instrumentation.
Flow Measurement
Flow measurement online tools, help guides, products types, questions and answers.
Advantages and Disadvantages of using a 4 to 20 mA Signal
A 4-20mA current signal has become very popular for many applications beyond it’s original intended purpose in the process industry. It is now used throughout industry as the preferred measurement and control signal for many different types of systems. Despite the popularity of the 4-20mA signal, it is not the best solution for every application […]
Not Reading Zero when Pressure is Vented to Atmosphere
It is not unusual for a pressure measurement device to read slightly above or below zero with no pressure applied.
How to Connect a 4-20mA Current Loop Pressure Transmitter
All devices connected to make up a 4 to 20 milliamp current loop are connected in series.
Symptons and Causes of Damage to Pressure Transducer Diaphragms
It is possible to view part of the diaphragm on most pressure transducers and some which are completely exposed such as flush diaphragms are particular vulnerable to mechanical damage.
Measurement Accuracy
There are many contributing error factors which go into a total uncertainty calculation. The way accuracy is defined for pressure instruments on technical data sheets can vary significantly across manufacturers and product types.
Measuring the Pressure of Hot Media
Installing pressure sensors close to high temperatures can lead to significant measurement errors and irreparable damage to the sensor & electronics.
Are all IP68 Water Resistant Protection Ratings the same
It is often assumed that devices with an IP68 rating are suitable for immersing underwater for an indefinite period at any depth. Not all devices that are IP68 are intended to be continuously submerged, some only require a temporary rating to protect from occasional submersion. For example a pressure transmitter installed below ground level will […]
Using an Absolute Sensor to Measure Gauge Reference Pressure
When it is necessary to present gauge reference pressure data, an absolute pressure sensor can be used in some situations if a gauge pressure sensor is not available. An absolute pressure sensor will measure total pressure independent of atmospheric pressure changes, unlike a gauge pressure sensor which measures pressure relative to atmospheric pressure. To convert […]
Determining the Signal Cable Length of a Suspended Liquid Level Transducer
Deciding the correct length of cable for a suspended IP68 transducer is an important part of specifying, if the cable is too short it is difficult and expensive to join two cables together and make the seal liquid tight. There are two separate parts of the installation that need to be considered to determine the […]
Why are Submersible applications so demanding of Pressure Transducers?
Placing a sensing device in a liquid is one of the most hostile environments to ensure a long reliable service life. The extra considerations for design engineers include: Keeping pressurised liquid out. Preventing condensation damage to the internal electronics. Corrosion protection for all the materials used in the transducer construction. Adequate protection from lightning surges […]
Transforming a 2 wire Current Loop into a Voltage Output Signal
If you are running a signal cable over a long distance or have a spare current output pressure transmitter, it is possible to convert the output signal to a voltage type to make it compatible with voltage only input devices. A typical current output is 2 wire 4 to 20 mA which is designed to […]
Does the type of Engineering Units matter for Pressure Transmitters
When selecting a part number for a pressure transmitter you will need to choose a pressure range. Usually a manufacturer will designate pressure ranges in the most common unit used by it’s customers. For the USA the most common unit is psi and for Europe it is bar, but what if you are working with […]
Considerations for monitoring Landfill Water Level
In recent years regulations for environmental control, health and safety issues have become much more stringent for existing and new landfill sites. The regulations encompass many considerations and some involve the measurement and control of water level in many positions around a waste disposal site. One application is ensuring contaminated water is contained within a […]
How does changes in Local Gravity affect Hydrostatic Pressure
The value of hydrostatic pressure for a fixed height column of fluid is directly proportional to the gravitational strength at a particular geographical location. Generally if the height above sea level is increased the hydrostatic pressure will decrease. Also since the world is wider at the equator than the poles the gravitational pull will increase […]
How Gravity affects the performance of Pressure Transducers
Any pressure transducer which relies on a force collecting diaphragm for sensing pressure, will be sensitive to a change in orientation. A pressure transducer diaphragm is designed to flex when a force is applied to it. If the diaphragm is orientated horizontally it will sag slightly under the force of its own weight. If the […]
Incompatible Pressure Sensor Specifications
We occasionally receive requests for combinations of pressure sensor features that are not practical to include in the same specification. Below is a list of the most requested parameter combinations that are declined including explanations. Low Pressure Range with High Media Temperature – the thin and large diameter diaphragms used in the construction of low […]
What does the suffix a, abs, d, dp and diff, g, rel and sg mean after the pressure units in a pressure range?
There is a loose convention across manufacturers for designating the type of reference that a pressure sensing device has, which can be confusing if you are unfamiliar with specifying this often overlooked but critical specification parameter.
Measuring the difference in air pressure between rooms
Monitoring and controlling the pressure in a room is a critical parameter in many indoor environments where the climate must be maintained at a particular temperature, humidity and cleanliness/containment level.
Why do you have to select an elastomer seal material for some types of pressure sensor?
When selecting pressure sensor options, occasionally you will come across a choice of seal materials to choose depending on the sensor design. An all welded construction provides a high integrity and homogeneous material design. The main disadvantages of this kind of sensor design is the lack of flexibility to customise for different applications, induced measurement […]
Calibration Hand Pump performance depends on test volume
Most air hand pumps that are designed to be used as pressure calibrators include a coarse pressure generator and a fine pressure adjuster. The effectiveness of both is dependent on the test volume connected to the pump. The coarse or main pressure generator is typically a piston and cylinder arrangement which is actuated either by […]
What is the difference between a pressure transducer and a transmitter
When browsing through pressure measurement products you will notice that some are called pressure transducers and others are called pressure transmitters.
What is the difference between gauge and absolute pressure measurement
Determining whether you need gauge or absolute reference pressure is a very important to selecting the right pressure range for a pressure instrumentation.
Improve the electrical termination of vented submersible pressure sensors
Submersible cable is more expensive because it has to be reinforced to support the sensor plus its own weight in deep holes without stretching which would lead to a change in sensor position and ultimately sensor calibration. A submersible cable also has a vent tube running through it to allow gauge reference pressure sensors access […]
What affects the performance of low pressure sensors
By their nature low range pressure sensors are very sensitive instruments and there a few factors that need to be considered prior to and during installation.
Supply voltage and load resistance considerations for pressure transmitters
In order for any pressure transmitter to function within designed performance levels, a min. supply voltage must be maintain device operation.
Measuring liquid level in a sealed tank with a hydrostatic pressure sensor
In order to measure the level of a liquid using a pressure sensor you must be able to subtract the pressure of the gas at the top of the tank.
How does the accuracy of pressure measurement devices change over time
Not even the most accurate pressure instruments will hold their accuracy indefinitely, all are prone to drift over time.
Determining the hydrostatic pressure range for a tank level sensor
There are many ways to measure the height of a fluid and one of the most popular is to use a pressure sensor.
Using a screw-in or waterproof pressure transmitter to measure liquid level
The first step in selecting a pressure transmitter for liquid level measurement is to determine whether to submerge or mount the sensor externally.
Using absolute pressure sensors to measure hydrostatic level
Venting a gauge reference hydrostatic pressure sensor to the outside air is not always possible and an absolute reference sensor has to be used instead.
Understanding operating temperature limit specifications for pressure transducers
Understanding the temperature limitations of a pressure transducer will help you extend the service life and prevent premature failures.
How to reduce submersible pressure sensor failures caused by moisture ingress
One of the main causes of failure in submersible applications of pressure transducers and transmitters is moisture ingress.
Pressure Sensor Accuracy Specifications
Understand what parameters are included in pressure sensor accuracy specifications and what techniques were used, so that a true comparison can be made.
IP65 sealing a vented gauge pressure transmitter with a DIN plug
For most general purpose applications the DIN43650 plug and socket connector is one of the most widely specified for industrial pressure transmitters.
Choosing calibrator for pressure transmitters
A guide on what to consider when choosing pressure calibration equipment for calibrating pressure transmitters.
Protecting a pressure sensor from high pressure spikes
When specifying a pressure range for a hydraulic system there maybe a risk of high pressure spikes.
Reduce calibration costs of analogue pressure gauges
Are your costs running high for outsourcing analogue pressure gauge calibration? Then maybe it is time to invest in your own pressure calibrator.
Pressure Measurement Glossary
Look up a word or phrase to find a page with more information on the chosen pressure measurement topic.
Selecting a pressure range for optimal service life and accuracy
What pressure range you select for a pressure measurement application affects the accuracy and the service life of a pressure transducer.
Dynamic pressure measurement with mV output transducers
For the best frequency response use a strain gauge pressure transducer that provides a mV output without any amplification.
Measuring vacuum with negative gauge or absolute ranges
There are two reference points for measuring a vacuum pressure.