Clamp-on ultrasonic technology is perfectly suited for portable versions of the flowmeter, as these devices need to be installed and removed without breaking the integrity of the pipe. Transducers are simply mounted externally and the measurement signal propagated through the pipe wall to achieve the measurement of flow. This non-wetted technology is particularly useful with aggressive or corrosive-process liquids and gases.
Portable flowmeters are particularly advantageous in certain cases: where intermittent measurement is required, to survey flow where no metering provision had originally been foreseen, or to check existing in-line flowmeters. A portable ultrasonic flowmeter needs a power supply, which is unlikely to be available adjacent to a new measurement point. An integral battery pack is therefore required, which has historically resulted in hazardous area use being controlled by a hot work permit along with the paperwork, downtime and working practices that this rightly requires.
Advancements in battery technology now allow portable flowmeters to be approved for use in hazardous areas. ABLE Instruments & Controls has been supplying portable ultrasonic technology since 1985, and worked towards such a solution for many years. The company designed a portable meter which achieved ATEX approval in April 2010.
However, the portable meter is often used as a temporary measurement solution. It is left to collect data over time, continuously monitoring variations in flow during operation or upset conditions of the plant. An integral power source suitable for hazardous areas is therefore not enough. Battery longevity and the ability to lengthen the period of operation are equally important.
ABLE’s portable ATEX flowmeter battery pack provides up to 24-hour operation and the ability to replace batteries within a hazardous area. The batteries are intrinsically safe and do not require the flowmeter to be directly connected to an external power supply in order to be charged.
The flowmeter weighs less than 25kg in its rugged aluminium case, making it suitable to carry onboard a helicopter for offshore service. The quick-install clamp-on ultrasonic transducers use award-winning WideBeam® technology. This provides accurate and reliable flow metering with high tolerance to wide flow velocities, fluctuating pressure and temperature and entrainment. The flow computer has all the necessary features, data logging capabilities and outputs needed for such a task. Unique zero-matic® path software eliminates zero drift and allows zero flow to be set without the need to shut down the flow. The device is the latest in ultrasonic flow metering technology.