Calibration Services - FAQ

Calibration Services - Frequently Asked Questions (FAQ):

FUTEK's A2LA and NIST-accredited calibration lab offers calibration and recalibration services for load cells, torque sensors, and strain gauge amplifiers. FUTEK calibration equipment is ISO 17025 and ANSI Z540-1 certified for high accuracy and fast turnaround.

How often should I get my sensor recalibrated?

As sensors are exposed to continuous usage, aging, output drift, overload, and improper handling, FUTEK highly recommends a yearly recalibration interval. Frequent sensor recalibration helps confirm whether the sensor maintained its accuracy over time and provides a load cell calibration certificate to show that the sensor still meets specifications and prepping the measurement systems for audits.

However, when the sensor is used in critical applications and harsh environments, load cells may require more frequent calibrations. Please consult with our Recalibration Team, who will help you evaluate the most economical calibration service interval for your sensor.

How do I know if my sensor, or system, passed calibration?

A sensor calibration must meet the sensor's non-linearity spec, which is found on the sensor's spec sheet. A system calibration, which is the calibration of a sensor and a digital instrument, must meet the sensor's non-linearity times two and is listed on a certificate as system tolerance. A note is added when a sensor, or system, does not meet the specifications.

This document explains every section of the calibration certificate and how to interpret it.

Why should I do a complete system calibration?

A measurement system usually encompasses the sensor, instrument or signal conditioner, cabling, and connectors. A full system calibration ensures that the whole system is performing accurately as expected.

Many of the system calibrations are done live and will need high-precision loads applied. Additionally, the system calibration also takes care of any connectors that may need to be soldered.

Choosing a complete system calibration allows you to start using your measurement solution out of the box. A system calibration creates a plug & play solution where all connectors, cables, and instrument settings are taken care of.

What calibration service comes with my load cell or torque sensor?

It depends on the type of sensor and what is specified on its spec sheet. Please refer to the sensor's spec sheet and look for the standard calibration specified and the loading direction (tension, compression, clockwise, counterclockwise) that is offered with the sensor.

I lost my certificate. How do I retrieve the calibration data?

Calibration summary information may be available online using the sensor's serial number. Please retrieve a summary of your sensor calibration data in our Online Calibration Tool here.

What is R.O.?

R.O. stands for rated output and will be the sensor's capacity, the last calibrated applied load, or the electrical equivalent of those points.

What is NL on my calibration certificate, and how is it calculated?

NL, or non-linearity, is the maximum deviation of the observed output of the sensor calibration curve from a theoretical straight line, ranging from zero to the last calibrated loading point. The difference between these two points is displayed as a percentage of the final calibrated loaded amount or rated output.

What does the zero mean on the table of the loading points?

The zero reading is to eliminate any zero offset (or load cell zero balance) and allow the span from the loading to be presented.

The zero is to show that the sensor was "tared out", or that any natural zero offsets and any effect of fixtures were removed before applying loads.

What is shunt?

Shunt is a positive change in output that is generated from an unloaded sensor when resistance is placed between the -signal and- excitation connections of the sensor. Shunt information can be used to check the health of the sensor over time and assist with setting up devices, such as DAQ systems, by providing a known output without a physical load needed.

Why is converted shunt information shown for a negative direction, or dual directions, when the result of the shunt is positive?

Electrical shunt output is presented into an equivalent load amount using the slope of all directions calibrated. This supplies confirmation of what the shunt change will be if using either direction of the listed calibration information.

How do I use the A2LA equation to convert my sensor's output?

A2LA information is presented in a polynomial equation with applied load indicated with x and output indicated by y. The output is found by solving for y where the applied load is placed in the equation for x. The applied load is found by solving for x where the observed output is placed in the equation for y.

What is "as found"="as left"?

"As Found" information on a calibration certificate is the observed performance of the sensor, or system, as it was first received at our load cell calibration lab. "As left" information is the result after any noted adjustments that are made to help bring the sensor, or system, into the specification. "As found"="as left" means that the "as found" information meets specification and no adjustments were needed to the sensor or system.

I see both "as found" and "as left" data on my calibration certificate, was there an additional charge for this information?

An "as found" and "as left", if necessary, are performed under the same load cell calibration service and do not incur and additional charge.

Tension is offered standard with my sensor; can I order compression only calibration and have both tension and compression?

Dual direction calibration must be performed at the same time and under the same environmental conditions and calibration setup to be effective. A dual-direction calibration service must be ordered to get valid dual-direction calibration information.

What should I send along with my sensor?

Please include all cables that came with the sensor. If you are requiring a full system calibration, please include the instrument alongside your sensor. We do ask that you remove all fixtures from the unit prior to shipment.

A checklist of items coming in for recalibration can be found here.

How long does recalibration take?

FUTEK's recalibrations typically take three or four business days upon receiving the unit. (If there are functionality issues, the turnaround time is around seven business days.) If you require expedited load cell recalibration, please contact our team and we will do our best to accommodate your schedule.

Did you know that FUTEK can perform on-site recalibrations?

Well, we can! Reach out directly to our Recalibration Team.

To get more information about load cell calibration, please visit our main Calibration Services Page. Ready to calibrate your Load Cell, Torque Sensor or Multi-Axis Force Sensor? Contact us to recalibrate your sensor.