Crane Wash Filter Plant - keeping things clean in Stratford
3 July 2007, News release from Pulsar Process Measurement Ltd
Pulsar Process Measurement has supplied ultrasonic level control equipment that is monitoring and controlling water levels in a crane washing facility in Stratford-on-Avon, protecting the local water course by minimising run-off and therefore avoiding pollution.
The crane firm in question is AGD, a large supplier of cranes for hire. When they come back into the yard, they have to be thoroughly cleaned and prepared for the next hirer. This is done in an enclosed crane wash area, where dirt from all types of construction sites is pressure washed off. The site is immediately next to the Stratford Canal, which then runs down to join the River Avon below the town. It is important that the water that is washed off the plant is not allowed to contaminate the canal. AGD commissioned Haith Industrial to supply a filter press, and Haith included three Pulsar units to monitor and control the process.
The dirty water from the crane wash flows into a pit, and then via a parabolic screen to a flocculator. Flocculant is added to the tank, and the resulting solids are drawn off to a filter press to create the final filter cake.
The Pulsar units control the process at three points. Clearly, there is only run-off into the sump while the cranes are actually being washed down, and the first unit, a Pulsar Blackbox, monitors the level in the sump. When enough dirty water is in the sump, a relay signal from the Blackbox switches on a pump to feed it to the flocculator. A further Blackbox unit measures the level in the flocculator itself, ensuring that there is no chance of an overflow. Once the solids have been drawn off, the remaining clean water is pumped to a large tank, which then forms the reservoir that supplies the crane wash. The third Pulsar unit, an Ultra 3, measures the level in this stock tank and controls a valve to keep it topped up from mains water. Both the flocculator and the sump are agitated to keep the solids mobile, so the Pulsar equipment has to provide a reliable signal with a turbulent liquid surface.
No waste water is discharged, the only product of the system is the filter cake, and the only input is the top up water.
Companies such as AGD have little other instrumentation on site, and therefore they don't have engineers to support this type of equipment. The Pulsar equipment has to be reliable so that people such as Dave Evans of Haith Industrial don't have to spend all their time solving site problems. As Dave said: "we're very happy with the Pulsar equipment that we buy. We buy a lot of ultrasonic equipment, and Pulsar has proved so reliable we have gone over exclusively to their equipment".