Quick Answer
Load cell calibration uses NABL-calibrated reference masses (for compression load cells) or a precision force standard machine (for tension/shear types). The calibration applies force at defined load increments and records sensitivity, linearity, hysteresis, and creep per OIML R 60 and ASTM E74.
Key Takeaways
- Load cell calibration parameters: sensitivity (mV/V), linearity error, hysteresis, and creep.
- Reference standards: NABL Class F1/F2 masses for low capacity; deadweight machines for high capacity.
- Calibration per OIML R 60 for trade-verified weighing systems.
- Prism calibrates load cells from 1 N to 5000 kN (500 tonnes) capacity.
- Load cell calibration certificate states sensitivity in mV/V/rated capacity and expanded uncertainty.
Load Cell Types Calibrated at Prism
| Load Cell Type | Configuration | Common Applications |
|---|---|---|
| Compression (canister) | Column or disc type, compressive loading | Weighbridges, silo weighing, press monitoring |
| Tension (S-type) | S-shaped body, tensile loading | Crane scales, overhead weighing, material testing |
| Shear Beam | Bending beam, single-ended | Platform scales, conveyor weighing, floor scales |
| Single Point | Bending beam, compact | Retail scales, counting scales, small platforms |
| Pancake / Low Profile | Very low profile, high capacity | Process weighing, hydraulic press monitoring |
| Pin Load Cell | Cylindrical pin replaces shackle pin | Crane hooks, lifting points, link pins |
Load Cell Calibration Procedure
Reference Setup
Connect NABL-calibrated reference load cell (Class A) in series with the test load cell, or use NABL-calibrated reference masses for deadweight loading.
Pre-load Cycles
Apply 3 pre-load cycles to 100% of rated capacity to condition the load cell and establish repeatability baseline.
5-Point Ascending Load
Apply load at 20%, 40%, 60%, 80%, 100% of rated capacity. Record mV/V output at each point.
Hysteresis Test
Release load in 5 steps. Record output at each step. Calculate hysteresis as max difference between ascending and descending readings.
Creep Test
Apply 100% rated load and hold for 30 minutes. Record output change — creep should be < 0.02% of rated output for Class C3 load cells.
Certificate
Issue NABL certificate with sensitivity (mV/V), non-linearity, hysteresis, creep, and expanded uncertainty. Include OIML accuracy class.
Frequently Asked Questions
What is load cell sensitivity and how is it stated on the calibration certificate?
Load cell sensitivity is the rated output (RO) in mV/V at rated capacity. A typical strain-gauge load cell has sensitivity of 2.0 mV/V ± 0.1%. The NABL certificate states the as-found sensitivity and deviation from rated output.
How often should load cells be calibrated?
Load cells in legal-for-trade weighing systems (platform scales, weighbridges) require annual NABL calibration. Load cells in process weighing (reactors, silos) should be calibrated annually or after any structural modification.
Can Prism calibrate load cells above 1000 kN?
Yes. Prism calibrates load cells up to 5000 kN (500 tonnes) using portable reference force transducers and hydraulic loading frames.
What is OIML R 60 for load cells?
OIML R 60 is the international recommendation defining the metrological requirements for load cells used in weighing instruments. It defines accuracy classes (C1 through C6) based on minimum dead load output, maximum hysteresis, and creep specifications.
Does load cell calibration require removing it from the weighing system?
For most load cells, laboratory calibration (requiring removal) gives higher accuracy. For permanently installed load cells (silo weighing, press monitoring), in-situ calibration using hydraulic loading frames is possible.
Written by
Er. Parthiv Kinariwala
Managing Director · Prism Calibration Centre · NABL CC-2480 · Ahmedabad
Er. Parthiv Kinariwala founded Prism Calibration Centre in 2004 and has over 20 years of hands-on experience in calibration engineering, NABL accreditation, and industrial compliance. His team performs 10,000+ calibrations annually from the Vatva GIDC laboratory, serving 5000+ industries across Gujarat.
Prism Calibration Centre — Vatva GIDC, Ahmedabad
Prism Calibration Centre
F-101, Rudraksh Complex 2, Phase 3, GIDC Vatva, Near Jasoda Nagar Cross Road, Ahmedabad — 382445, Gujarat, India
Phone: +91 98245 26444
Email: info@prismcalibration.com
NABL: CC-2480 · ISO/IEC 17025:2017
Hours: Mon–Sat, 9:00 AM – 7:00 PM