Croft quarry in Leicestershire needed to control stone level in choke-fed tertiary crushers. Pulsar's equipment helps to maintain the optimum level in the crusher bowl to maximise production efficiency and consistency of stone size, ignoring the high levels of acoustic and electrical noise present on the plant. Equipment used: Level Star controller (now Ultra 3 controller) dB3 transducer Stone crushers work best when they are full, referred to as "choke fed". The weight of stone pushing down into the crusher increases the efficiency of the process, giving a more efficient use of the equipment and a more even stone size. At Aggregate Industries' Croft Quarry in Leicestershire, Pulsar Process Measurement non-contacting ultrasonic level control equipment has been used to control the level of stone in part of the crushing process. The electrical contractors at the quarry, Protech Electrical Services Ltd, chose to use Pulsar's Level Star level controller [now integrated within the Ultra 3 controller], coupled with their dB3 transducer. The system uses echo processing techniques to measure the level of stone in the crusher, and maintain it between 90% and 70% of the "full" level using a relay to switch a vibratory feeder. A quarry is a very noisy environment, both acoustically and electrically. The Pulsar system is set up to undertake initial signal processing at the transducer head, which can be up to 500m away from the Level Star, so the signal between the transducer head and the controller is extremely resistant to electrical noise. Simple two core shielded cables can be used to connect the transducer with the Level Star [now integrated within the Ultra 3 controller]. The Pulsar system is an ideal solution to the application. The non-contacting measurement means that it is maintenance-free, and the sophisticated echo processing software built into every Pulsar system means that a reliable signal is received regardless both of how the stone lies in the crusher and the level of dust in the air. The dB3 transducer is designed for accurate level measurement up to 3 metres range. Pulsar manufactures transducers that will measure up to 50m range, and for stock control/inventory management application the Level Star control unit will convert distance measurement to volume or weight. [The Level Star controller is no longer available as an individual controller, all the specifications and features of the Level Star controller are now integrated within the Ultra 3 controller]. Posted from the Pulsar archives - April 2011.