Bourdon Tube is a flattened length of thin hollow metal tubing which is formed into a C shape.
Measurement & Instrumentation Guides
Guidance and reference articles for sourcing, setting up and using measurement equipment.
Burst Pressure
Burst pressure is a design safety limit which should not be exceeded. If this pressure is exceeded it may lead to mechanical breach and permanent loss of pressure containment.
Bonded Seal
Bonded seal is a metal washer with an elastomer seal bonded to its inside diameter, which is used to provide a pressure seal when placed between two flat surfaces that are screwed together using a male and female parallel thread.
BFSG – Bonded Foil Strain Gauge
Bonded foil strain gauges (BFSG) are metal based foil elements that are incorporated into a flexible electrically insulating material which can then be bonded to a surface with adhesives. As stress is applied to the material, the BFSG will deform and the resistance changes. If a voltage is applied across the BFSG it can be […]
BSL – Best Straight Line
Beast straight line (BSL) is the mathematically derived straight line which runs through the middle of a set of readings in such a way to achieve the smallest error across all the results. The measurement precision of a device is often specified in relation to the maximum deviation from the best straight line.
Vacuum
This guide provides an overview of measuring vacuum pressure including suggested vacuum measurement products and question & answers.
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.
Compensated Temperature Range
The compensated temperature range defines the limits of operation for a specified measurement accuracy. e.g. A pressure sensor has an accuracy of 0.25% full scale over a compensated temperature range of -20 to +80 degC. Since temperature errors are often significant for many measurement devices, a manufacturer will incorporate digital or analogue temperature compensation. If the measurement device is […]
HVAC
Product selection & help guide for measurements on a HVAC systems in buildings & laboratories.
Bidirectional
Bidirectional is typically used to indicate that a particular parameter such as an electrical signal or measurement range will generate values in both the positive and the negative direction. For example a sensor which has a -10 mbar to + 10 mbar gauge pressure range with a 0 to 10 Vdc output is said to […]
Food Grade
Food grade products and substances are designed to be safe when used inside equipment and processes which are used in the production of food, pharmaceuticals and drink. Food grade products and substances prevent contaminant substances from entering the food manufacturing process which could cause physiological harm.
UKAS – The United Kingdom Accreditation Service
The United Kingdom Accreditation Service (UKAS) is a national organisation recognised by the UK government which audits and certifies calibration standard laboratories in the United Kingdom. Those who use the calibration services of a UKAS accredited laboratory are assured that the calibration will be carried out to a very high standard.
Overpressure Protection
Overpressure is used to describe a condition where the pressure value has exceeded operational limits or a threshold pressure.
Al2O3
Al2O3 is the chemical formula for Alumina (Aluminium Oxide) which is a ceramic material that has high caustic chemical resistance and electrical insulation.
Ratiometric
Ratiometric is used to describe an output signal which changes in proportion to a change input or supply voltage.
M10 x 1
This is a metric fine thread with a outer diameter of 10 millimetres and a thread pitch of 1 millimetre.
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?
daPa – Dekapascal Pressure Unit
Find conversions for the daPa (dekapascal) pressure unit.
Measurement Signal
A guide to measurement signal types for sensors & instrumentation, with explanations, applications and choice of products for analog & digital signals.
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.
mV/V – Millivolts per Volt Output Signal
It is an electrical signal which is proportional to the applied excitation voltage and is also referred to as a ratio-metric or strain gauge output.
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.
Barometric Pressure
A guide to barometric pressure measurement including explanations, applications and choice of products for measuring barometric pressure.
Pressure Calibration
This guide will answer many of your questions about using & selecting pressure calibration equipment.
Using Hydrostatic Pressure Transducers for Measuring Fluid Level
There are a number of methods and technologies for measuring the level of a fluid with hydrostatic pressure transducers.
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.
Stainless Steel Pressure Sensors
There are many materials used for constructing pressure sensors, but those made from stainless steel are considered the most reliable and durable.
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.