Pulsar Process Measurement Ltd have supplied The Wrightington, Wigan and Leigh NHS Trust with Modbus-enabled Ultra 5 non-contacting ultrasonic measurement systems as the first phase of a project to monitor and control fuel oil stocks across four major hospitals. The new systems will allow staff to monitor and re-order fuel oil from a central location, improving safety by removing a need to access the tanks, reducing the risk of over-ordering and fuel stagnation and improving efficiency.


A major hospital maintains a significant fuel oil stock on site, in the case of Wigan’s Royal Albert Hospital this amounts to 80,000 litres over two tall tanks. Besides providing some fuel to feed the main, dual-fuel boilers, hospitals also maintain emergency back-up electricity generators and by law must store enough fuel on site to run them for a minimum of three days in case of power cuts. Fuel oil is therefore an important commodity, with a total of more than 200,000 litres held across four sites within the Trust. Tank gauges and dipsticks have been in use, meaning that staff had to access the top of these high, vertical tanks to take measurements which were then recorded manually, with the obvious potential for an accident to occur.

Phase two of the project involved Leigh Infirmary, which has two fuel oil tanks totalling 40,000 litres capacity. Pulsar supplied Ultra 5 level controllers with a local display of volume, volt-free contacts for alarm use and optional Modbus connectivity, and an ultrasonic transducer was selected that mounted simply to the top of the 6m high vessels. The transducer emits a pulse that reflects from the liquid surface, the same transducer picking up the returning signal and calculating the distance. The Ultra 5 controller than uses a pre-programmed routine to convert that measurement to display the contents of the tank – in this case in litres. The Ultra 5 controllers are wall-mounted local to the tanks so that staff can simply read off the measurement with no need to access the tank itself, while the Modbus connection provides the ability to link the signals to a desktop display.

Commenting on the installation, Trust Engineer Mark Hogan said, “We are really pleased with the Pulsar equipment and the advice and support we got. Our people no longer must climb the tanks, and our aim is to manage stocks and regulate deliveries right across the Trust from a desktop system.”