When using a Beam Style wrench to tighten fasteners, make sure you look at the pointer straight on with the scale, otherwise reading from an angle may make it appear to read higher or lower than the setting required.
Some Beam Style wrenches have a plastic handle on the end which acts as a a pivot point. The handle needs to be centred on its pivot while tightening the fastener for it to be as accurate as possible. If either end of the pivot handle is touching the bar it will change the effective length of the arm and the amount of torque that is applied to the fastener.
These wrenches have an adjustable handle and internal spring. By twisting the handle this adjusts the setting to the required torque value. Once the desired pre-set torque value is reached while tightening a fastener, the wrench will "click" and slip slightly, which helps to prevent too much torque being applied. The great advantage of using this style of wrench is that your don't have to necessarily look at the scale, it's all by feel of when the "click" happens.
As Adjustable Torque Wrenches can go out of calibration over time, it's important to ensure you have someone like TWCS who has the experience and equipment necessary to keep your tool in check and most importantly in calibration!
These are typically the most accurate, generally with +/-2% accuracy, and have easy to read gauges.
As these are precision tools, they are not only the most expensive, but should also be handled very carefully. Like other torque wrenches, they still need to be kept within calibration and also have to be checked regularly.
All electronic Torque wrenches require batteries. TWCS recommends the practice of removing the batteries from the wrench when it is not in use. Old batteries can leak and damage your wrench components.
The accuracy on your wrench should always be within +/-4%. Your wrench should be accurately calibrated from the factory when bought new, but this is not always the case either, I have come across quite a few that are not within calibration after being purchased. Always check you have been provided with a certificate and that the seller can guarantee the readings are accurate before purchasing a new wrench.