Q. What should one look for in a load cell calibration service facility?
A. Ultimately, your measurement requirements will dictate this. Most calibration facilities will have documented procedures for calibration however, have they documented the uncertainties involved with each procedure? How certain that your 1000 lb load cell is reading 1000 lbs when it returns from the calibration facility? That will be dependent on how well they determine the calibration uncertainty. ISO standards do dictate that uncertainties be determined, but this does not guarantee that you will be getting a calibration that provides uncertainty well below the manufacturer's performance specification. As compression calibration values vary significantly based upon setup, it is best to have calibrated as close to the intended use as possible. See technical paper for more details.
Q. How often should one have their load cell calibrated?
A. The manufacturer will recommend every year. What they typically won't tell you is that once a year is not always necessary. ASTM E-74 is the standard used by NIST. The requirement of that standard is that a load cell used to calibrate other load cells be calibrated one year after it was manufactured. If it is stable, it can go to a two year interval and remain as such until it proves to have instability beyond a certain amount. Keep in mind that this is for a load cell that is used to calibrate other load cells. Other standards do apply. However, if you are using a load cell to measure the pulling force of swimming sea turtles (yes, this is a true application) once a year, it is probably safe to say that spending the funds to have this equipment calibrated once a year would be wasteful. Ultimately, check for a governing standard in your industry. If there isn't an applicable standard dictating intervals, develop your own interval based upon sound judgement, experience, and past data. However, keep in mind that if required, justification will be necessary as to the interval chosen, but if chosen on sound principles and documented as such in your processes, that should not be a problem.
Q. Can one calibrate their own load cell?
A. The answer is yes. For example, if you are familiar with micrometers, you are most likely familiar with the fact they they are dimensional devices that need to be calibrated as well. This is typically performed with gage blocks, which many companies have on-site. The gage blocks are used by trained individuals and that saves the company money by preventing every set of micrometers from having to be sent out for recalibration. It is only the standard (the gage blocks) that are sent out at various intervals. As with the Force Calibration Machine (FCM), a company may have many load cells that may be calibrated with this standard. It is by using this standard and having it calibrated once every year or two that a customer is able to save time and money. Also, it provides a customer to be able to calibrate a system rather than just the load measuring device. As a result, internal calibrations and measurements can be conducted while complying with any internal quality standards such as ISO 17025 and ISO 9001.
More questions? Feel free to contact us!
A. Ultimately, your measurement requirements will dictate this. Most calibration facilities will have documented procedures for calibration however, have they documented the uncertainties involved with each procedure? How certain that your 1000 lb load cell is reading 1000 lbs when it returns from the calibration facility? That will be dependent on how well they determine the calibration uncertainty. ISO standards do dictate that uncertainties be determined, but this does not guarantee that you will be getting a calibration that provides uncertainty well below the manufacturer's performance specification. As compression calibration values vary significantly based upon setup, it is best to have calibrated as close to the intended use as possible. See technical paper for more details.
Q. How often should one have their load cell calibrated?
A. The manufacturer will recommend every year. What they typically won't tell you is that once a year is not always necessary. ASTM E-74 is the standard used by NIST. The requirement of that standard is that a load cell used to calibrate other load cells be calibrated one year after it was manufactured. If it is stable, it can go to a two year interval and remain as such until it proves to have instability beyond a certain amount. Keep in mind that this is for a load cell that is used to calibrate other load cells. Other standards do apply. However, if you are using a load cell to measure the pulling force of swimming sea turtles (yes, this is a true application) once a year, it is probably safe to say that spending the funds to have this equipment calibrated once a year would be wasteful. Ultimately, check for a governing standard in your industry. If there isn't an applicable standard dictating intervals, develop your own interval based upon sound judgement, experience, and past data. However, keep in mind that if required, justification will be necessary as to the interval chosen, but if chosen on sound principles and documented as such in your processes, that should not be a problem.
Q. Can one calibrate their own load cell?
A. The answer is yes. For example, if you are familiar with micrometers, you are most likely familiar with the fact they they are dimensional devices that need to be calibrated as well. This is typically performed with gage blocks, which many companies have on-site. The gage blocks are used by trained individuals and that saves the company money by preventing every set of micrometers from having to be sent out for recalibration. It is only the standard (the gage blocks) that are sent out at various intervals. As with the Force Calibration Machine (FCM), a company may have many load cells that may be calibrated with this standard. It is by using this standard and having it calibrated once every year or two that a customer is able to save time and money. Also, it provides a customer to be able to calibrate a system rather than just the load measuring device. As a result, internal calibrations and measurements can be conducted while complying with any internal quality standards such as ISO 17025 and ISO 9001.
More questions? Feel free to contact us!
MVProducts and Services, Inc.
Phone: 704-657-9410
Fax: 866-366-2556
Phone: 704-657-9410
Fax: 866-366-2556
Last Updated: June 2010
© 2009 MVProducts and Services, Inc.
© 2009 MVProducts and Services, Inc.