Castle Calibration
for immediate help or booking call us on 01723 584250 or email

Frequently Asked Calibration Questions

Do you have a question about our calibration and repair service? Check out the Frequently Asked Questions below! Can't find the answer you're looking for? Contact us!

Returning instruments to Castle Group for calibration, service or repair is a simple procedure. Instruments should be returned in their original packaging, where possible, or in suitable packaging which will prevent damage.

Equipment returned for service, repair or calibration should be sent to:

Service Department
Castle Group Ltd
Salter Road
Scarborough Business Park
North Yorkshire
YO11 3UZ

When returning items such as sound level meters or vibration meters please include all parts of your kit, including calibrators, cables, cases, microphones, accelerometers, etc. Please note that calibrators are charged separately to meters during calibration.

Upon receiving your instruments Castle Group will asses their current state and raise a quotation depending on the amount of work required. If your instruments are in good condition and only require service and calibration you will be quoted according to current prices. Any repair work which is required will be included in a quote and no work will be carried out until agreed between yourself and Castle Group.

Castle Group produces a price list for instrument calibration, all of which can be found at Each instrument falls in a particular pricing band which is scaled depending on the functions of each meter.

If you have a piece of equipment that you can’t find on online, don’t worry. Contact us to speak to one of our highly trained engineers who will do their utmost to help.

Each piece of equipment will be charged separately, and the prices listed cover service and calibration. Rest assured that we’ll never undertake any further work without your approval, and a reasonable charge for replacement parts and labour will be quoted to you first.

Our target is to turn around calibrations within a working week and we endeavour to do this at all times. If you’re in need of a shorter turn around, contact us and we’ll do our best to arrange this for you.

During busier periods and where any additional repair or replacement work needs to be carried out this may take longer due to acquiring parts etc.

To speed up the process, it’s always recommended to ensure you supply your official order as your equipment arrives with us, allowing us to begin work immediately.

Rental options are available should you require temporary replacement instruments during a repair or calibration.

Instruments such as sound level meters and vibration meters have to conform to a strict standard and annual calibration ensures that your meter is working correctly and giving accurate and reliable measurements.

All calibration work done by Castle Group comes with a traceable certificate or UKAS certification (when requested).

For more information about exactly what you’re getting for your money, contact us and speak to one of our service and calibration engineers who will be more than happy to help.

It’s well known that Sound Meters inevitably need to be calibrated to keep performing accurately, but a question we’re often asked is, “How often does my Sound Meter need to be Calibrated by a calibration lab?“. Answering this question is both easy and a not so easy, dependant on a few factors.

Here’s the easy answer:

The maximum interval between calibrations as advised UKAS:

  • Dose meters – 1 year, although there should be an extended level of testing every other year
  • Sound Level Meters to IEC61672 – 2 years
  • Other Sound Meters (built to older or different standards) – 1 year
  • Calibrators – 1 year
  • Barometers (as supplied with Castle Class 1 calibrators) – 1 year

All of the figures stated above are guidelines of the maximum interval, and they assume that equipment is in regular use and are supported by good working practice. In non-typical use, such as:

  • in areas with high or low moisture,
  • in extreme temperatures, or
  • where equipment is used irregularly

it’s then appropriate to calibrate your equipment more frequently.

The not so easy answer depends entirely on various factors

  • Instrument specifications and manufacturer’s instructions – What does the manufacturer recommend.
  • Any requirements of the test specification – Does the application specifically define a maximum calibration period.
  • Expected use of the equipment – heavy use or harsh environments should shorten the calibration period.
  • Review of calibration history – The calibration period should be reviewed and changed if necessary; a history of stable results may increase the period.
  • Reference to the maximum period recommended in the table at the back of the LAB23 document depending on the type of equipment used.

There is some very clear guidance on the subject from UKAS (United Kingdom Accreditation Service) and you can download their document by following the link –

There is one further point that you should consider and that is whether you are ever likely to have to rely on your measurements in court in defence of a noise induced hearing loss claim. In this case, all equipment should be calibrated at least annually. You won’t find this point in any UKAS guidance, but is just something we have learned first hand with our experience of mitigating noise induced hearing loss claims.

Summary – Sound Meter Calibration

As you can see, the general statement that equipment is okay to be calibrated every 2 years largely isn’t true, so you should be aware that this should at very least be reviewed regularly!

And please don’t forget that a proper calibration is not just a few points checked with an acoustic calibrator – we are talking about a full check of the electrical performance of the equipment at multiple points of frequency and level without the microphone fitted, followed by acoustical checks also at multiple frequency and level points, with the microphone included as part of the system – beware ‘cheap’ calibration houses as you will get what you pay for!

Contact Us Today To Get Started

You can find out pricing and build your calibration quote online, or alternatively fill in the contact form below and one of our expert engineers will contact you as soon as possible and help you as best we can.

Or call and speak to one of our service and calibration engineers who will be happy to help 01723 584250

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