Flow measurement expert Katronic’s ultrasonic clamp-on flowmeters measure 16 RAS/SAS (returned/surplus activated sludge) lines in pipes up to 85 years old, in a large sewage treatment works. They were supplied by ABB and installed by Z-Tech. A novel approach saved a lot of time during the commissioning process.
Accurate measurement of RAS/SAS flow is vital to properly balance sludge processes. The sixteen grey cast iron pipelines, ranging between 80 and 790mm diameter, have had between 60 and 85 years of sludge running through them and building up on their inner walls.
Portable flowmeters provide 24-hour flow surveys. Katronic flowmeters share a common ultrasonic platform and user interface, so a trial performed using a Katronic portable will exactly match the operation of a fixed system.
Following the successful trial, the water company purchased 16 KATflow 150 fixed systems. Smaller pipes are measured with a single path (one pair of transducers) and those over 300mm diameter use two pairs to improve accuracy where flow may be inconsistent. The transducers are remotely positioned between 50 and 80m from the transmitters. Stainless-steel mounting rails were used to position the transducers accurately and firmly to the pipe.
A positioning assistant on the main display of every flowmeter gives dynamic feedback on transducer placement, so a compact Katronic Commissioning Module can be used with a KATflow 200 portable flowmeter in a way that lets operators remain by the pipe to position the transducers correctly, giving an identical result when the remote KATflow 150 transmitter is connected. KATflow 150 transmitters can be fitted with up to 11 outputs. ABB initially supplied the flowmeters with active 4-20mA outputs. Z-Tech subsequently adding a Profibus PA output card to each flowmeter to link to the site SCADA system. For more information, contact: Martin Hardwidge, firstname.lastname@example.org.