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SOI – Silicon on Insulator

SOI – Silicon on Insulator

Silicon on Insulator (SOI) is a type of material technology which can be utilised in the manufacture of pressure sensor diaphragms to allow operation at higher temperatures.

Repeatability

Repeatability is the amount of change in a measured reading at the same measurement point after a defined number of cycles over the measurement range or a set of environmental limits.

Accuracy

Accuracy of a measurement instrument defines how much a measurement value may deviate from the perfect measured value.

Precision

Precision is the measure of how closely a set of readings will be to a reference line that passes through the middle of all the points.

PVC – Polyvinyl Chloride

PVC is a widely used plastic which is cheap to produce and hard enough to be used as a component parts construction material.

PUR, PU – Polyurethane

Polyurethane is a durable polymer used for coating cables, a water tight sealing compound and a potting compound to protect electronics from damage.

FFKM – Perfluoroelastomer

Perfluoroelastomer (FFKM) is a seal material type which has a much higher temperature rating than the more common FKM and can be used on temperatures up to 300°C. FFKM also has a broader chemical resistance than FKM.

Oxygen Service

Select Oxygen service measurement products to use in atmosphere which contains high levels of Oxygen or measure gas containing high concentrations of O2

NO – Normally Open

Normally Open (NO) refers to the state of an electrical switch contact which stays open until a preset threshold has been met and the switch closes, e.g. a NO pressure switch set at 10 bar will close once the pressure exceeds 10 bar.

NC – Normally Closed

Normally Closed (NC) refers to the state of an electrical switch contact which stays closed until a preset threshold has been met and the switch opens, e.g. a NC pressure switch set at 10 bar will open once the pressure exceeds 10 bar.

NL – Non-Linearity

Non-Linearity is the deviation error derived from the straightness of a set of recorded measurements when compared to a straight line, such as bsl or tsl, drawn through all the results. The maximum non-linearity error is normally expressed as a percentage of full scale.

NPL – National Physical Laboratory

National Physical Laboratory (NPL) – national measurement institute for the United Kingdom. This organisation is responsible for maintaining the primary measurement standards for the UK.

Mechanical Stop

Mechanical Stop is an internal component which protects pressure sensing components from overpressure by limiting the deflection of the diaphragm.

MTBF – Mean Time Between Failures

MTBF or mean time between failures is a theoretically calculated value which considers all the components used in the construction of a measurement device.

MSL – Mean Sea Level

MSL or Mean Sea Level is the average height of the ocean surface. Mean sea level is a significant datum reference for meteorological and altitude related pressure measurements, e.g. standard atmospheric pressure at mean sea level is 1013.25 hPa or 29.92 inHg.

Long Term Stability/Drift

Long Term Stability or Long Term Drift is the amount of change of a measured reading at exactly the same pressure and ambient conditions over a given period of time which is typically quoted as an annual figure.

Isolation Diaphragm

An Isolation diaphragm is a thin membrane which is used to isolate the media on one side of a diaphragm from media on the other side.

IP Ratings

The IP Rating is an accepted engineering standard for defining the protection of electrical equipment from dust and moisture ingress.

Pressure Hysteresis

Pressure Hysteresis is the difference between two separate measurements taken at the same pressure but one where the pressure was increasing and the other where the pressure was decreasing. The hysteresis is caused by the natural reluctance of a pressure sensing material such as a diaphragm to return to its original position, shape or form […]

Gauge Reference Pressure

Gauge reference pressure is a pressure measured relative to atmospheric or barometric pressure. The most used pressure reference is gauge pressure which is signified by a (g) after the pressure unit (e.g. 30 psi g), and means that the pressure measured is the total pressure minus atmospheric pressure. There are two types of gauge reference […]

Flush Diaphragm

A guide to flush diaphragm pressure & level measurement instrumentation, including explanations, applications and a choice of products with flush process fittings.

FSO – Full Scale Output

Full Scale Output (FSO) can have two meanings. The first meaning is that it is the resulting output signal or displayed reading produced when the maximum measurement for a given device is applied. The second meaning applies to the difference between the minimum and maximum output value. Full Range Output (FRO) and Full Span Output […]

FS – Full Scale

Full Scale (FS) is the difference between the lowest and highest possible measurement point

FKM – Fluoroelastomer

Fluoroelastomer is a fluorinated carbon based rubber material which is mostly used on pressure measurement equipment to seal joints between components which are either pressurised or water-tight.

Dry/Dry

Dry/Dry describes a differential pressure measurement device which is only compatible with dry/non-condensing gas on both the positive and negative pressure side.

Dry Cell

Pressure sensing technology which excludes any fluid filled components. The advantages of a dry cell pressure sensor are: More sensitive and responsive to measuring low pressures No risk of oil contamination if the containment isolation diaphragm fails. Compact size Lower cost of manufacture  

Digital Compensation

Digital compensation is the process of correcting measurement signals using look up tables or mathematical formula.

Ceramic Pressure Sensors

Ceramic pressure sensors are devices which have sensing diaphragms made from Alumina (Al2O3) with either a screen printed thick film strain gauge circuit or a variable capacitance cell. Ceramic diaphragms are very inert and provide a high level of protection from aggressive chemicals.

Cardinal Points

Cardinal points are the markings around the outside of a round analogue gauge dial which define the measurement increment divisions.

Bourdon Tube

Bourdon Tube is a flattened length of thin hollow metal tubing which is formed into a C shape.

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.

Period to Frequency Calculator

This tool will convert the period to the equivalent frequency value, by calculating the number of cycles or revolutions per unit period of time from the time it takes to complete one full cycle or revolution, f=1/T, ω=2π/T

Frequency to Period Calculator

This tool will convert frequency to a period by calculating the time it will take to complete one full cycle or revolution at the specified frequency, T=1/f, T=2π/ω

Area to Diameter of Circle Calculator

This tool will calculate the diameter of a circle from the area, and will convert different measurement units for area and diameter, ø=2√(A/π)

0 to -2000 Pa vacuum transmitter

Pressure transmitter with a 0 to minus 2000 pascal pressure range and 2 wire 4 to 20 mA output signal. DMP343 Low Range Pressure Sensor Pressure Range: 0 to minus 20 mbar (-2000 Pa) gauge Output Signal: 4-20mA (2 wire) Electrical Connection: DIN43650A plug IP65 Pressure Connection: G1/2 DIN 3852 male

River & Coastal Water Submersible Level Sensor with SDI-12 interface

The most popular device is the SLS-D submersible level transmitter with SDi-12 output, this can be supplied with various measurement ranges and cable lengths to suit the installation. There is also the SLS-DMB which is a ceramic based sensor with a Marine Bronze housing which is suitable for permanent submersion in estuary and seawater installations. USB-SDI12-PRO […]

Volume & Density to Mass Calculator

This calculator is used to determine the mass from the volume and density, and show a conversion scale from volume to mass centred around each calculation, m=Vρ

Mass & Density to Volume Calculator

This calculator will determine the volume of a substance from the measured mass and known density, and also display a mass to volume conversion scale, V=m/ρ

Mass & Volume to Density Calculator

This calculator will determine object density from entered mass and volume, and display two conversion scales of mass vs density and volume vs density, ρ=m/V