How can I determine the best Hei-TORQUE model for me? With a few simple questions, you can identify which of the new Heidolph Hei-TORQUE overhead stirrer motors would be appropriate for you. Do you want to accurately measure torque in Ncm, or is a general indication (bars like phone signal) acceptable? → If a Ncm reading is required, you need a Hei-TORQUE Ultimate (Hei-TORQUE Precision). Otherwise, a Value would be fine. Do you want to connect the overhead stirrer to a computer software system for automated monitoring or control? → If yes, you need a Hei-TORQUE Ultimate (Hei-TORQUE Precision), for an RS232 (or USB) interface. What level of torque (turning force) do you require – low, medium or high? This is related to the viscosity of your application – e.g. if you are stirring viscous materials, you need an overhead stirrer with high torque. If you are currently using an overhead stirrer, you can consider the torque of that (at your stirrer speed). → Low torque (low viscosity) – you can use a 100 model. Please note, however, that we do not typically recommend a 100 unit for use with Reactor-Ready – a 200 or 400 would be preferred. → Medium torque (medium viscosity) – a 200 model should be acceptable. → High torque (high viscosity) and low speeds – you need a 400 model. Please note, if you want to work at medium to high speeds, a 200 model would provide more torque than a 400, because the 400s have 2 different gears – different speed ranges with different maximum torques. Please refer to the graphs below: If you require any further guidance, please feel free to contact us – we’ll be happy to help.