Calibration

Calibration FAQs

• What is calibration?

  When you are measuring something accurately, you need to know that the results are really what they say they are. Therefore, it’s necessary to compare your measurement capability to some reference. This might be a simple hand-held calibrator, or reference to an absolute standard in a National laboratory. The choice depends on the purpose for which your measurements are to be used.

• Why should you calibrate your equipment?

  Modern instrumentation is very accurate and reliable. But it’s not perfect and can go wrong, sometimes in ways which are not completely obvious. This is exacerbated by the fact that precision instrumentation is used in hostile environments, such as building sites, where rain, dust, handling and corrosive substances can affect your measurements. For example, dropping an accelerometer on the ground may break a crystal – the device will still have an output, but it may not be as linear as it was when delivered. A calibration will allow you to check this and have confidence going forward. Think of it as a kind of MOT test for your instrument.

• Where are calibrations performed?

  There are many laboratories around the UK which can offer calibration of sound & vibration measurement equipment, and the calibration will be performed in a laboratory under climatically controlled conditions, using equipment which is itself traceable to national laboratories. Of course, calibration can also be performed in the field, using portable calibrators, but the uncertainties will be larger than a laboratory calibration.

• How often should I get my equipment calibrated?

  The standards are not proscriptive on this, but as a rule of thumb, instruments should be re-calibrated every two years, and calibrators annually. For example, the recommendation in BS 4142:2014 follows this approach for industrial noise measurement. However, if your measurements are really critical, you may wish to calibrate more frequently.

• What is a calibration standard?

  Most measurement instrumentation will be built to a national or international standard – for example, BS EN 61672-1 defines the characteristics of sound level meters. A ‘calibration standard’ will define how that instrument is calibrated, so in this case, BS EN 61672-3 documents the procedures for calibration. Very often, calibration standards don’t exist for some types of instruments, so laboratories will perform a series of tests, using their own procedures, to check conformance with the instrument standard.

• What is a traceable calibration?

  When a device is calibrated, you need to know that the reference equipment is also correct within certain tolerances. This sets up a hierarchy of calibration, where you can trace your measurements up to a higher standard. The reference equipment will itself be calibrated behind the scenes, and the documentation allows you to follow that hierarchy typically to a national standard. In practice, all calibrations will have some form of traceability.

• What is UKAS calibration

  UKAS is the United Kingdom Accreditation Service which is a body which audits the procedures and performance of calibration laboratories. UKAS accreditation therefore ensures the laboratory meets minimum standards, often laid out in instrumentation standards. Note that a UKAS calibration may be no better than a well-documented traceable calibration, but it will certainly be more expensive. However, it will often be required if there are legal implications for your measurements.

• Where can I find my calibration certificates

  Calibration certificates can be found on the AcSoft Calibration portal or by emailing wjay@acsoft.co.uk. New purchase equipment is provided with hardcopy calibration certificates only. 

• How can I check my sound level meter's microphone is working?

  Spot calibration performed with a Sound Calibrator at 94dB or 114dB. Microphone tolerances are provided by the manufacturer themselves.

• How long does my calibration last for?

  Most calibrations are valid for 2 years unless this is a microphone set, calibrator, ear/mouth simulator or an impact hammer. Measurement systems or data analysers have a 2 year calibration period but are reccomened to be calibrated yearly due to the units function.

• How often should I get my device calibrated?

  If it has been calibrated in the past this should have a cal due date. If not we recommend yearly for traceability and so we can keep track of the units results and deviations

• Do you offer UKAS calibration?

  We are currently in our UKAS accreditation process but we our lab is not yet accredited to UKAS standards. We do work alongside other labs with UKAS accreditation so this is a service we can provide.

• How long does calibration take?

  Length of calibration can vary depending on the kit but we always aim for a 1-3 day turnaround. Specialist kit can and usually will take longer than 1-3 days but we work alongside the customer to ensure their deadlines are met.

• What is tests are performed during calibration?

  Different tests are performed depending on the kit but we will always test the most sensitive sensors, microphones or any equipment actively performing measurements. Depending on the equipment we will provide tests in accordance with the relevant standards the equipment is manufactured to where possible. 

• What do I need to send in for Calibration?

  The best way to send in your equipment is to send it in for calibration with all the relevant equipment you use alongside the meter or unit. Sending in all cables, microphones, geophones, accelerometers, calibrators etc. This will allows us firstly to see how the equipment is used / its function and to also avoid any delays when asking for cables or sensors that are alongside the kit.

• How do I prepare my equipment to be sent in for calibration?

  No need to worry about clearing or wiping any settings or setups on the meter. We save all settings and setups prior to calibration so these can be applied again once calibration is complete. All that needs to be done is to make sure the equipment is sent in safely and to ensure the equipment is wrapped up in protective wrapping or bubble warp to ensure no damage is done when in transit. 

• How can I perform checks on my unit to ensure it is in working order?

  Depending on the kit the checks you can perform to ensure compliance vary. The best way to check is to look online for manufacturers recommendations and spot calibration setups. If you cannot find a spot calibration setup online then get in touch with the Lab and we can recommend checks and spot calibrations that will be relevant to the equipment.