• Home
• Products
• Reference
• Contact

• Instrument Type
• 4-20mA Transmitters
• 0-5, 10V Transducers
• mV/V Sensors
• Digital Sensors
• Absolute Sensors
• ATEX Transmitters
• Calibration Pumps
• Calibrators
• Digital Gauges
• Digital Manometers
• DP Transmitters
• Indicators - Pressure
• Liquid Level Sensors
• Loggers - Pressure
• Loggers - Liquid Level
• Switches
• Accessories
• Your Application
• Absolute Reference
• Air/Pneumatics
• Barometric/Atmospheric
• Certificates & Approvals
• Data Logging
• Differential
• Electrical Signal
• Flush Diaphragm
• Gauge Reference
• High Accuracy
• High Frequency Response
• High Range
• High Temperature
• Intrinsically Safe
• Level Measurement
• Low Ranges
• Measuring Range
• Media Compatibility
• Miniature
• Overpressure Protection
• PC Interfacing
• Pressure Calibration
• Process Connection
• Testing
• Sensor Technology
• Submersible
• Temperature & Pressure
• Vacuum
• Water Level
• Water Pressure
• Your Industry
• Manufacturers

Home

Pressure Sensor and Instrumentation News

Installation tips for improving the measurement accuracy of pressure transmitters and extending the operational service life

For the best frequency response from a pressure sensor use an un-amplified piezo-resistive transducer that provides a mV output directly from a strain gauge bridge.

There are two reference points for measuring a vacuum pressure: either you can measure how much the pressure is below local atmospheric pressure or how much it is above absolute zero vacuum.

The TK Industrial Pressure Transmitter is now available from stock and can be delivered within 24 hours

The DMP331P flush diaphragm pressure transmitter can be used on liquids or gases up to a maximum temperature of 300 Degrees Celsius.

Unfortunately if you are looking for a black and white answer to this question it is not as simple as that. Distinguishing between a pressure transducer and a pressure transmitter can depend upon which country you are working in and which manufacturer you are dealing with. As with a lot of engineering terminology the original definitions have become a little blurred and have not always been used in the way that was originally intended.

The PD33X high precision differential pressure transducer can measure with an accuracy of ±0.15% full scale over a temperature range of -10 to +80°C with the analogue signal output and ±0.1% with the RS485 digital output signal.

Not all pressure transmitters use the same sensing technology and some are more suited to measuring high pressures than others. It is high pressure spikes that are the most common cause of pressure transmitter failure and they will punch or rip a hole in a diaphragm if the right precautions are not implemented.

Determining whether you need gauge or absolute reference pressure is as important as selecting the pressure range itself, particularly for low pressure measurements. If you get it wrong your measurements are going to be out by approximately 1 bar, which could be a huge error if you have specified a 10 bar range for example.

Pressure sensors that utilise silicon sensing elements offer many advantages over other pressure sensing technologies, they are small, lightweight, highly repeatable, stable over time, dynamically responsive and very sensitive to variations in pressure.

Differential pressure measurement can be one of the most complex and confusing applications when it comes to choosing the right pressure sensor for the job. Not only must you consider the differential pressure range required, but also whether the sensor is designed to withstand the system pressure which is often much higher than the differential pressures being measured.

Primary pressure standards such as dead weight testers offer the highest level of pressure measurement precision and accuracy for most pressure calibration laboratories, but they are mostly manually operated and the results have to be typed into the computer or handwritten into calibration reports.

The LMK331 Screw-In Level Pressure Sensor has an aggressive media resistant construction which makes it suitable for measuring fluid level of a wide range of corrosive chemicals.

If you break down the SI unit (Systeme International d'Unites) for pressure which is the 'Pascal' (Pa) you can begin to understand why there are so many types of pressure measurement units.

The AS motor-sport pressure transducer is an economical sub-miniature pressure sensor specially designed for use on auto-racing engines and chassis systems.

Prolonged immersion in saline liquids will lead to irreparable damage to pressure measurement instrumentation if the sensor housing is not made from a corrosion resistant material that is suitable for long term submersion in corrosive fluids such as sea-water.

The DPS low differential pressure transducer is an affordable sensor for measuring air-flow differential pressure in semiconductor processing clean-rooms, pharmaceutical research laboratories, building ventilation air ducts and factory air conditioning.

CNS rangeable low range level transmitters are specifically designed for shallow depth sensing in reservoir, rivers, streams, water treatment works, weirs, water tanks, filtration pits and open channels.

On the SensorsONE website you will find an online Pressure Sensor Application Tool (PSAT) to help you select specification parameters for pressure transducers & transmitters.

Measuring low pressures requires very sensitive diaphragms and many of the sensor technologies that are available are only compatible with low humidity gases.

The PD-39X Differential Pressure Transmitter uses two absolute pressure transducers to measure the pressure on the positive and negative side ports.

Typically hydraulic methods are used to apply force or weight loading on a sample of material such as concrete or soil. When carrying out destructive testing high level pressure spikes are generated when samples start to weaken in reaction to the stresses being applied.

Traditional transducers for measuring the pressure of plastic melt extrusion use mercury or oil filled capillaries to isolate the sensing element from the very high media temperature and require a relatively thin isolation diaphragm to transmit the pressure through the fluid.

Digital Autozero & Span is a new contactless calibration adjustment option for the TK Industrial Pressure Transmitter and the TPSA Precision Pressure Transmitter.

The KL1 termination enclosure is used to connect submersible cable at the top of a borehole or well to less expensive overground cables which run back to the control and monitoring station.

0.1% accuracy battery powered digital pressure gauge with intrinsic safety option for hazardous areas available to order or buy online.

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. They may look as robust as any other pressure sensor on the outside housed in a high IP rated stainless steel case, but inside there is a very thin diaphragm which is highly sensitive to acceleration and mechanical stress.

In order for any pressure transmitter to function within its designed performance levels a minimum voltage must be maintained across the two electrical connections to the device. Since the electrical configuration is a current series loop circuit any load resistance added to the circuit will consume power resulting in a voltage drop across the component. This voltage drop must then be subtracted from the available voltage supply in order to determine the net voltage available for powering the pressure transmitter.

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. This is straightforward if the head of the tank is vented since the pressure will be the same as the atmospheric pressure and the pressure sensor can use a pressure reference which is vented to atmosphere. However the storage tank maybe isolated or restricted in some way from venting to atmosphere, perhaps to prevent hazardous liquid vapour escaping. In these cases the pressure in the top of the tank maybe higher or lower than the outside air pressure and therefore the pressure sensor will need to be compensated for the gas pressure in the head of the tank.

Although it is not always clearly explained on manufacturer’s technical data sheets there are two widely used ways to define the room temperature accuracy of a pressure sensor. The relevance of each will depend on how you intend to install the pressure sensor and how important it is to achieve the optimum accuracy.

Not even the most accurate pressure instruments will hold their accuracy indefinitely; they are all prone to drift over time. Any device that is constructed to measure pressure is going to have some complexity in its construction incorporating an assortment of materials with different physical properties. When exposed to many pressure and temperature cycles these materials will expand and contract and drift by varying degrees from their original state.

Two of the main factors influencing the type of hydrostatic level sensor to use for a particular application are the viscosity and the corrosive nature of the liquid being measured.

There are many ways to measure the height of a fluid and one of the most popular is to use a pressure sensor since any change in liquid height above the pressure sensor is linearly porportional to the change in pressure exerted by the head of liquid immediately above the pressure sensors position.

The first step in selecting a pressure transmitter for liquid level measurement is too determine whether to measure it by immersing the pressure transmitter or by mounting it externally to an outlet pipe or the wall of a storage tank.

Measuring hydrostatic liquid level is normally carried out using a vented gauge reference pressure sensor. However, venting the inside of a pressure sensor to the outside world is not always possible and when it is, failures can occur due to internal condensation particularly with submersible pressure sensors and loggers.

If the process pressure you are measuring has a dynamic temperature range, determining whether a pressure transducer is going to tolerate the temperatures it will be subjected to will ensure a longer service life and prevent premature failure.

Battery powered digital pressures gages are generally more accurate and easier to read precisely than mechanical dial pressure gages.

One of the main causes of failure in submersible applications of pressure transducers and transmitters is moisture ingress either via liquid seeping in through the interface between the cable and the pressure sensor or down the inside of the cable from the cable termination at the surface. In order to minimise the risk of moisture penetration some design features and installation practises need to be considered to ensure the submersible pressure sensor lasts as long as possible.

Unfortunately there is no universally adopted convention for specifying the accuracy of pressure sensors. Although there are standards such as IEC60770 and DIN16086 most manufacturers do not specify them in their data sheets. It is therefore up to the user to analyse each data sheet to understand what parameters are included in the accuracy statement and what technique was used so that a true comparison can be made.

For most general purpose applications the DIN43650 plug and socket connector is one of the most widely specified for industrial pressure transmitters. The DIN 43650 plug is very low cost and a IP65 ingress protection rating can be achieved if it is joined correctly to a cable. However care must be taken not to block the vented gauge reference of the pressure transmitter whilst seeking to achieve an IP 65 seal.

In order to convert a current output to a voltage signal for a analogue voltage input card it is necessary to add a load resistor in series with the current loop and use the resulting voltage drop across the load resistor as the input signal.

For long cable runs of 10's or 100's of metres it is necessary to select a high level voltage signal or a pressure transducer which is not going to be easily corrupted or diminish over a long distance.

There are a multitude of strain gauge diaphragm types that are currently being used in the manufacture of piezo-resistive pressure transducers but they all use the same fundamental method to convert pressure into an electrical signal.

Ad hoc applications for pressure testing new products or production machinery do not necessarily require an elaborate data acquisition system with many input channels permanently connected to a PC. If the test is to be carried out in a intrinsically safe area a simpler approach becomes even more desirable.

First you must determine the highest overall accuracy you will need to achieve for the pressure transmitters you will be calibrating. This does not necessarily have to be the manufacturer’s specification since very often the pressure transmitter accuracy is much better than the required system accuracy.

Some fluids will corrode stainless steel over time and although the erosion of material is only fractions of an inch per year in many cases, this is significant when considering the thickness of level sensor diaphragms which can vary between a few thousandths of an inch to 2mm. In these types of applications ceramic sensor elements offer excellent corrosion resistance to the most aggressive media such as acid or alkaline liquids.

For the highest possible pressure sensor accuracy you will need an output signal which is not easily corrupted and has a very high resolution.

For level measurement of fresh-water boreholes with diameter restrictions of less than 1 inch the choice of hydrostatic level sensors becomes much more limited since most are typically 1 - 1.5 inches in diameter.

Hydraulic pressure test stands can be extremely unforgiving to some pressure transducers especially in high dynamic systems which are testing hydraulic actuators or valves.

The mV output is the least processed out of all the different types of pressure transducer output and it is particularly suited to low power consumption and high dynamic response applications.

To improve measurement performance of barometric measurements of a pressure transmitter, the 4-20mA output signal is scaled from 800 to 1200mbar absolute rather than the more usual 0 to 1200 mbar absolute.

If your costs are running high in order to maintain ISO9000 adherence for calibrating pressure gauges used on production machinery, maybe it is time to invest in a precision digital manometer.

All pressure sensors measure relative to some kind of pressure reference. The majority of pressure sensor technologies rely on the physical movement of a sensing diaphragm and the actual pressure measured is the difference in pressure between both sides of the diaphragm.

It is not always necessary to use a process pressure transmitter which is rangeable, repairable and full of digital gizmos in a hazardous area, some times a straightforward 4-20mA signals with no digital functionality will do a more than adequate job for a much lower cost.

OEM manufacturers of measurement instrumentation which have to measure pressure inside their product often choose to integrate the signal conditioning within their own electronics. This enables the manufacturer to use a pressure transducer that has no signal conditioner or compensation electronics fitted and therefore reduces its size and cost.

On most manufacturer's pressure sensor data sheets you will find an over-pressure or proof pressure rating. This is the maximum pressure that the pressure sensor will tolerate without damaging the diaphragm or putting it outside specification tolerances.

Measuring the pressure of high viscosity fluids that congeal at low temperatures is likely to lead to problems with pressure sensors that have recessed diaphragms.

When specifying a pressure range for a hydraulic system there maybe the risk of high pressure spikes caused by sudden opening and closing of valves similar to what happens when you turn a water tap on or off too quickly and generate a knocking sound due to the sudden stress applied to the water pipe.

The harsh corrosive environment which level sensors are subjected to on a ship call for a corrosion resistant construction and robust mechanical design.

What pressure range you select for a pressure measurement application effects the accuracy and the service life of a pressure transducer.

The TK industrial pressure transmitter is a budget pressure sensor with a moderate accuracy developed for pneumatic automation & hydraulic system applications such as CNC machinery, packaging machines, hydraulic press and robotics, where reliability, robustness and affordability are valued higher than precise pressure measurements.

Measuring aggressive media directly can lead to a short life for sensors if they have not been designed and tested for use with a corrosive fluid. The Grundfos direct sensors range of pressure sensors have been developed for long lasting service on boilers, heating and other water management systems.

Home

Request Info | Ask a Question

Site Last Updated:  03/09/10