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CALIBRATION AND CHECK OF YOUR PRIMA 100 LWD - ADVICE FOR PRIMA USERS
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13/09/2006 |
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A falling weight deflectometer is a very precise measuring device and requires absolute calibration every other year to ensure correct measuring results. Incorrect measurements may have serious consequences for a pavement, as the calculations basing on the data will not be reliable.
 Carl Bro Pavement Consultants offers annual absolute calibration of all kinds of FWD equipment. Our calibration equipment is built into a suitcase which makes it mobile. In this way we can perform calibration on site.
Another solution is to buy the equipment. Contact Carl Bro Pavement Consultants for an offer and further information.
Why is it important to calibrate FWD equipment? Measuring equipment should always be calibrated frequently. Often this can be done in connection with a service visit, where the equipment will be overhauled anyway. If equipment is not calibrated then the measurements will not be correct and data will cause wrong interpretations and solutions. If these solutions are applied in connection with consultancy work, a consultant may end up facing large claims for damages from a client.
Actions for damages can be very expensive if you are not able to prove that the FWD measured correctly. Having an up-to-date equipment means that it will be possible to find out what caused the error and avoid claims and unsatisfied clients.
CBPC calibration equipmentCBPC has developed calibration equipment, which works with the newest technology and principles within this sphere. Furthermore, the equipment is portable allowing us to bring along the equipment to the customer to be used on site.
The calibration procedure
When CBPC calibrates geophones (displacement transducers), three different calibration parameters are used:
• Off set
• Cut off frequency
• Slope
The off set and the natural noise influence the analog card and the channel. The system compensates for this automatically. This means that in practice the value is 0.
Cut off frequency is the exact frequency where the system must compensate for the non-linearity in the low frequency range.
Slope is the amplification required to make geophone and calibration reference show the same peak value.
The three software values have the advantage that they do not change over time and the current development of the calibration can be followed.
Calibration is done at a given rise time (frequency) and peak value, which may be changed by the operator as required.
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