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Prompt Pressure Calibration

On-site and off-site pressure calibration available nationwide

Accredited calibration of all types of pressure devices including pressure gauges, vacuum gauges, manometers, barometers and more!

Pressure Calibration

Calibrate.co.uk are specialists in the calibration, repair and servicing of pressure equipment, and we are able to provide pressure calibration quickly for a great price.

Whatever your requirements, whether they be onsite or offsite, give us a call to discuss your needs.

We currently able to calibrate pressure equipment such as sensors and gauges within the following parameters:

  • Clean Air: -1 to 700 bar & -1 to 200 bar
  • Mineral Oil: -200 to 700 bar

Please find below a list of our equipment capabilities. Pressure sensors and gauges are sadly not included in our 3 day or free promise.

Pressure Equipment Type 3 Day or Free
Barometers No
Digital Manometers No
Drucks (Digital Pressure Indicators) No
Force Gauges (to 1000N) No
Oil Pressure Gauges (700bar) No
Air Pressure Gauges (200bar) No
General Pressure Gauges (2800bar) No
Relief Valves No
Roughness Gauges No
Vacuum Gauges No

If your item you want calibrated, give us a call and we may still be able to help!

Pressure Gauges (0-40000psi)

We can accurately test and measure all types of gauges with our traceable hydraulic calibration equipment. When testing a gauge we conduct rising pressure tests and falling pressure tests. This ensures that your gauge accurately measures increases as well as decreases in pressure.

As well as calibration of pressure gauges, we also offer minor repairs and readjustments of zero errors and range errors.

Vacuum Gauges

We can calibrate vacuum gauges up to -1bar. To do this we use a fully traceable pressure calibrator which can precisely pull a vacuum from zero to -1bar.

Chart Recorders

We also calibrate pressure chart recorders. To do this we use our traceable hydraulic pressure equipment and our precise temperature calibration equipment. However, please remember when you send your chart recorder in for recalibration that you make sure to include the corresponding charts for your device.

Digital Pressure Gauges

We calibrate these in exactly the same way as normal pressure gauges. However, we also perform basic functionality checks on your device to make sure everything is working correctly. Since digital pressure gauges often have additional functions, these checks can help to spot common problems and steps can be taken to repair them.

Digital Manometers

To accurately calibrate these devices we apply a known pressure from a reliable, traceable source to national standards. We then increase the pressure in periodic steps across the full range of the instrument, ensuring that your meter is operating to its full capabilities.

Pressure Release / Pressure Relief Valves

We can calibrate and set release valves to the customer’s required parameters. When sending in your relief valve, you can state the pressures you would like the valve setting to. If no values are stated, we will calibrate the whole scale of the unit.

Drucks (Digital Pressure Indicators)

We perform multiple tests when calibrating a druck. The first set of tests we perform are rising pressure tests; the purpose of these tests is to make sure that your druck is maintaining pressure and also that the pressure your druck is outputting is stable and accurate.

Secondly, we test all electronic functions of your druck. This includes voltage, current and resistance measurements.

On-Site Pressure Calibration

We pride ourselves on the experience of our technicians. Many have worked for many years in the offshore, oil, gas, chemical and petrochemical industries. To discuss your on site pressure calibration requirements give us a call.

We have previously carried out sub contract on site calibrations for many companies not just in the UK but also in the following regions and countries.:

Africa, Asia, Europe and the Middle East, Azerbaijan, Bahrain, Oman, Cyprus, Kuwait, Nigeria, Russia, UAE, Saudi Arabia.

To get in touch with us either fill in our calibration request form or alternatively call us directly on 0845 365 3944.

Further reading regarding calibration of a pressure gauges:

Pressure Calibration – Calibration of a Pressure Gauge

Pressure measuring instruments are commonly used in a wide range of applications. From pressurized bottles to domestic gas appliances and from natural gas boarder stations to liquid truck containers, pressure instruments are frequently found in various installations. In order to ensure the proper performance of pressure instruments, regular calibration must be performed. There are several types of pressure measuring instruments, but the following three types are mainly handled by calibration laboratories:

–       Manometers with analogue or digital indication

–       Pressure Transducers

–       Pressure Transmitters

Manometers with analogue or digital indication

These manometers are complete mechanical measuring instruments that indicate units of pressure (bar, Pa, psi, etc.). Depending on the application they may consist of the following parts:

–       Manometers with analogue indication:

  • Pressure transducer
  • Analogue conditioning module
  • Electrical power supply unit

–       Manometers with digital indication:

  • Pressure transducer
  • Analogue conditioning module
  • Analogue to digital converter
  • Digital processing module
  • Electrical power supply unit

Both types, analogue and digital, can be also equipped with analogue or digital outputs (alarm signals etc).

Pressure Transducers

They convert the measured pressure into an analogue electrical signal that is proportional to the applied pressure. Depending on the model and the application, the analogue output signal can be voltage, current or frequency. Pressure transducers need external continuous power supply.

Pressure Transmitters

They are units consisting of a pressure transducer and a module for conditioning and amplifying the transducer signal. Depending on the type and application, the output information of a pressure transmitter can be voltage (5V, 10V, etc), current (0-20mA, 4-20mA, etc), frequency or a digital format such as RS 232. Pressure transmitters also need external continuous power supply.

Accuracy of pressure measuring instruments is defined by their accuracy class. In the table below, accuracy classes are presented as mentioned in EN 834-1/6:

Accuracy Class

Limits of permissible error

(% of span)

0.1

± 0.1 %

0.25

± 0.25 %

0.6

± 0.6 %

1

± 1 %

1.6

± 1.6 %

2.5

± 2.5 %

4

± 4 %

The most common instruments used by calibration laboratories for pressure calibration are Dead Weight Testers and Pressure Calibrators.

Dead Weight Testers use known traceable weights to apply pressure on a fluid for the purpose of checking the accuracy of pressure measuring instruments. They use a piston cylinder on which a load is placed to make an equilibrium with an applied pressure underneath the piston. Dead weight testers can operate either hydraulically or pneumatically. These testers are considered to be highly accurate and they are characterized as primary standards.

Pressure Calibrators are the most frequently used instruments for pressure calibration. They are digital instruments and they can be handheld or benchtop. They can contain internal or external pressure pump, internal or external pressure transducers and they can also be intrinsically safe for use in potential explosive environments. Pressure calibrators can contain electrical or temperature modules in order to be able to measure and/or generate voltage, current and temperature. These instruments are really easy to use and are very convenient especially for on-site pressure calibrations.

METHOD OF CALIBRATION – CALIBRATION EXAMPLE OF A PRESSURE GAUGE

Before beginning any calibration procedure, all other metrological requirements must be met. The instrument must be left in the laboratory to stabilize for sufficient time into the environmental conditions. The condition of the pressure gauge must be checked to ensure that there is no obvious damage or malfunction. Special care must be given to the manufacturer’s specifications about mounting position, torque or any other special requirements.

In the example below, we will assume that our reference standard is a pressure calibrator with internal pump. The pressure gauge must be connected to the output of the pressure calibrator. Attention must be given to the connections’ tightness in order to avoid leakages which will affect the measurement result.

Before proceeding to the calibration procedure, an initial check must be performed, in order to determine the pressure gauge’s condition:

–       Operate the instrument and bring it at least twice to its upper pressure limit and keep the pressure for at least one minute.

–       During the first pressure rise, check out the indication obtained for the conformity with the specifications.

–       Read the indications of the gauge at 0%, 50% and 100% of its measurement span.

The most usual calibration procedure is the Basic procedure described in Euramet/CG-17/v.01 “Guidelines on the calibration of electromechanical manometers”:

Calibration is performed once at 6 (six) pressure points (spread over the measuring span of the gauge) in increasing and decreasing pressures. Repeatability is estimated from 3 (three) repeated measurements at one pressure point (preferably at 50% of Full Scale).

At each pressure point at least the following data shall be recorded:

–       The pressure indicated by the reference instrument

–       The indication of the instrument under test

–       The values of the influence quantities (temperature, atmospheric pressure)

–       The identification parameters of the instrument under test

–       The identification of the instruments included in the measuring system

The calibration report must present the results in a way that they can be easily evaluated by the end user. Besides the mean value of the increasing and decreasing pressure measurements and the deviation of the mean value from the reference value, the repeatability error and the hysteresis error must be presented as well.

Hysteresis relates to the mechanical hysteresis of the sensing diaphragm where the reading of the pressure gauge varies depending on whether the pressure has been increasing or decreasing prior to the measurement. The hysteresis error is defined as the deviation in value between the increasing and decreasing pressure value measured at the same step point.

Now, let’s assume that we are using the above procedure to calibrate a pressure gauge having a range of 0-40 bar. The calibration report shall contain a table similar to the following one, presenting the results of the calibration:

 

Instrument Indication

Standard Pressure

Deviation

Hysteresis

Increasing Pressure

Decreasing Pressure

Mean Pressure

(bar)

(bar)

(bar)

(bar)

(bar)

(bar)

0.0

0.000

0.000

0.000

0.000

0.000

8.0

7.947

7.920

7.933

-0.067

0.027

16.0

15.847

15.807

15.827

-0.173

0.040

24.0

23.802

23.784

2.793

-0.207

0.018

32.0

31.815

31.808

31.811

-0.189

0.007

40.0

39.809

39.809

39.809

-0.191

0.000

 

There must be of course one more column in the aforementioned table, containing the measurement uncertainty.

In our example, where the calibration concerns an analogue pressure measuring instrument, there are several sources of uncertainty. Some of them are presented below:

–       Uncertainty of the reference instrument in the conditions of use (calibration certificate uncertainty, long term stability, environmental conditions, etc)

–       Uncertainty due to repeatability

–       Uncertainty due to the finite resolution of the instrument under test

–       Uncertainty due to hysteresis of the instrument under test

–       Uncertainty due to estimation of the head correction between the instrument under test and the reference instrument

–       personal bias in reading analogue instruments

Following the principles of the EA-4/02 “Expression of the Uncertainty of measurement in Calibration” we can evaluate the uncertainty for each measurement value.

Written by Sofia


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