Variable Area Flowmeter Alarm System

Lee-Dickens Ltd. (UK) has launched a single channel variable area (VA) flowmeter alarm unit suitable for use with a wide range of VA flow meters including models supplied by Emerson and Yokogowa. The BU191 sensor and alarm system is configurable and can be used to alert engineers to low or high gas flow conditions.

Originally designed for BNFL Ltd. for use at Sellafield, the SIL2 /IEC 61508 rated system can easily be fitted retrospectively and used to monitor the flow of any type of gas. The sensor head contains an infra red source and detector and is fitted around the flowmeter to be monitored. It is supplied with 5m of cabling to allow the sensor to be connected to its associated alarm unit. The system includes a sensitivity adjustment allowing it to cater for different flow rates.

The alarm panel features three LEDs which alert engineers visually to the status of the gas flows and power. A white LED indicates that the power status is ‘on’, a separate LED shows green to indicate a healthy level of gas flow changing to red if there is a problem. A third ‘instrument fault’ LED shines amber when power is lost either by the alarm unit or at the sensor head.

Should a power outage cause this LED to switch to amber – it can only be cleared by restoring power, replacing the sensor head and passing the float from the Alarm State to the Healthy State and then by pressing reset.

These units are particularly appropriate for operators monitoring the safety of gas flows in the food, drink, chemicals, pharmaceuticals, nuclear and power industries. The BU191 can be AC or DC powered and fits a variety of meters including the Emerson 1100, Emerson 1300 and Yokogowa RAGK series VA flow meters.