Load and torque measurement services are vital for the machine building industry, but this measurement is also relevant in some other applications. From load cell sensors to strain gaging services and torque analyzers, engineers who are in need of a measurement product or service that can be integrated into a piece equipment need to consider a range of options when looking for the right company for sensing and measurement systems.
Most load cells use strain gauge technology. This technology is very well established and has been proven for more than 40 years. Load cells are frequently used as part of a weighing system because they offer non-intrusive, highly accurate load measurement data, with properly installed and calibrated load cells routinely achieve an accuracy of around 0.03 to 1% (depending on load cell type). Load cell and torque sensor units are designed to operate in a wide temperature range of -452 degrees F to 450 degrees F. Hydraulic load cells can operate at temperatures of -60 degrees C (-76 degrees F).
There are five types of the load cells depending on the primary and secondary element that is used to sense the force. These are: strain gauge type load cells, hydraulic load cells, diaphragm load cells, spool type load cells and ring type load cells.
Precise torque measurement is required by many industries, such as engineering, for various tests. There is also a requirement for modern engines to have improved mechanical performance by increasing their rotating speed, and improved accuracy in various areas including efficiency measurements. There is continuous development in torque measurements. The original design principle of the torque shafts are still employed for specific applications; however the full range of transducers from HBM now includes shaft and flange design torque measurement as well.
Torque is a significant measurement service in a range of applications, including gas turbines. A torque wrench is a tool used to precisely apply a specific torque to a fastener such as a nut or bolt. It was invented by Conrad Bahr in 1918 while working for the New York City Water Department. Torque is an important measurement for almost everything, including the screw caps on medicine bottles, and for many products the permitted tolerances are mandatory. Custom torque sensors exceeding the calibration limit are exercised to their nominal capacity but are only calibrated to 360,000 lbs.in.
Power plants, process plants, ship operators, movable bridge owners and
pharmaceutical labs require accurate knowledge of torque and power in their
rotating machinery to monitor or control their operation. The power delivered
and consumed by engines, motors, turbines, propellers or waterjets provides an
indication and diagnostics of several operational parameters including efficiency, changes or deterioration over time, misalignment, fuel consumption and more. Using measurement services to perform accurate torque and horsepower measurements
using bonded strain gages and wireless telemetry systems can constantly monitor torque and power in areas where that type of permanence is required.
The technology to measure torque and power is the same regardless of
customer, equipment size or application. Two measurements must be obtained:
Torque and Rotational Speed (RPM). Torque is measured using bonded strain
gages whereas RPM is measured using hand held devices, encoders, magnetic
pickups or any other rotational pulse type signal.
For Field Measurements, torque is measured by bonding a full Wheatstone strain gage bridge to the shaft selected for testing. The signal is sent to the data acquisition equipment using a wireless/telemetry system. The signal, which is proportional to torque, is acquired by data acquisition equipment consisting of a computer, data loggers or multimeter. For Permanent Installations, torque and RPM are measured using the same sensors. Using inductively coupled transmission systems or slip rings (when
appropriate) accomplishes transmission of the signal. The data acquisition system typically consists of a display meter with an analog or digital output for connection to a computer based installation.
ISO9000 and many other standards specify the maximum period between recalibration as once every two years and more frequently if the instrument deterioration is significant during that period (typically more than 1%). Calibrating an instrument involves comparing the measurements of two instruments; one with a known magnitude or correctness (standard device), against which you measure the unit under test.
Measurement service engineers are ready to discuss specific torque sensing applications and measurement requirements for your company’s needs.