Batch controller ensures exact dispensing

16 August 2011

Precise sensing and dispensing of liquids into a container or process vessel in food, chemical, pharmaceutical, oil & gas and other process industry applications is promised by the new RA33 batch controller from Endress+Hauser.

The controller is designed to monitor flow, temperature and density; controls valves and pumps; and dispenses the exact amount requested by a programmed recipe. It can work with a single valve and pump in automatic or manual mode, or with two valves for two-stage batching. Two controllers can also work together for batch mixing of two ingredients.

The exact volume to be dispensed is calculated based on an analog or pulse signal from a flow sensor and its built-in temperature/density compensation functions. Mineral oil, for example, can be corrected according to the ASTM D1250-04 standard. The volumes of other media can be corrected using expansion coefficients, or the volume can be converted to mass by measuring the density. The RA33 makes an automatic after-run correction to ensure constant and accurate results, and error diagnostics help to detect leakage, fill deviation and "no flow" conditions.

The unit accepts inputs from flow, temperature, pressure and density sensors. Outputs can control two valves and two pumps, and it has up to four digital outputs for one- or two-stage valve control or for the control of other devices such as signal lamps. It also has optional USB, RS485, Ethernet, and Modbus TCP and RTU interfaces for communications with an external control system or PC