A batch controller calculates the number of items or the volume of things that are being processed at any given time. If these are solid objects, they work in the form of counters to calculate individual things, but when it comes to gas or liquid, these batches need to be counted by other means. Liquids and gasses pass through tubes when they are transferred and the volume of material must be communicated in the form of velocity, such as through rate per minute. A flow meter deals with volume and the batch controller displays the amount of liquid and gas that is passing through the tanks to the tubes.
When looking for a batch controller, you may select one that accepts pulses per second and gives rates and total readings for batching functions. You should also see hardware and software features and clear monitoring that is accurate and easy to read. You could find a controller that can monitor remotely or up close and can print out results as needed.