Product Announcement from Cooper Instruments & Systems
Torque is measured by either sensing the actual shaft deflection caused by a twisting force, or by detecting the effects of this deflection. Selecting torque measurement equipment can be difficult since different models offer their own advantages. The right supplier can help you select the best equipment for your application. You should choose a supplier with the knowledge and experience to assist before, during and after the purchase. After you've identified the right equipment, in order to obtain accurate measurement, you still need to install it correctly and you will need instrumentation to go with it. Here are some guidelines to help you identify the right equipment for your application.
Understand your Application
First, you must determine that you want to measure torque. Applications for torque sensors include determining the amount of power an engine, motor, turbine, or other rotating device generates or consumes. In the industrial world, you may encounter quality control specifications that require companies to measure torque during manufacturing, especially when fasteners are applied.
Next, you'll need to determine if you are going to measure reaction or rotary torque. A rotary torque sensor is used when you need the transducer itself to rotate, whereas reaction torque transducers are used to measure torque loads where the sensor doesn't have to rotate, as they will only rotate as much as the shaft will deflect (if you turn them too much, they will overload or break). Another component in understanding your application will be your testing environment. Will the sensor be exposed to extreme temperature, corrosive liquids, intense vibration, etc.? Other considerations that may influence your final decision are size, cost, availability and special requirements.
Define your Capacity Requirements
As with load cells, you'll want to choose a capacity over the expected maximum operating torque, so as not to accidentally overload the sensor. Don't forget to factor in all extraneous torque and over hung loads before deciding on the capacity you'll need. While a torque transducer is capable of measuring torque accurately with some radial load, as the radial load increases to the point where an appreciable moment load is applied to the shaft, the resulting deflection will cause output error. You also need to determine if you'll be using the sensor for testing clockwise, counterclockwise or both.
Define your Needs
Consider how you'll be mounting your sensor (for example: flange to flange, square drive, shaft to shaft, etc). If your application requires a rotary sensor, you need to define the RPM requirement for your sensor also. You want to make sure that you mount the sensor in such a way that it "sees" only rotational loading, if possible and not radial loading from whatever is attached. However, one must be cognizant of how support bearings, if employed, can cause errors through drag force caused by bearings and seals. This is also the point at which you'll want to consider size, connectors, accuracy and cost. What kind of output will you need - mV/V, VDC, mA? Finally, determine if you need a built-in encoder to measure speed and angular deflection
Select Instrumentation (if necessary)
If you need an instrument for your application, select it at the same time you select the pressure sensor. This will help ensure the compatibility of the entire system. Don't forget to purchase system calibration with your order. This integrates your sensor and instrument as one system.