However, a recent ARC study states that price and the economic downturn will remain the major issues working against broader market penetration.
While the initial price of ultrasonic flowmeters remains higher than that of other technologies, high accuracy ultrasonic models can be more cost-effective than well-established magnetic flowmeters (magmeters) for line sizes of greater than eight-inch diameter. Capabilities are increasing considerably and prices are dropping at a steady pace, fueled by rapidly growing market demands.
Ultrasonic technology has evolved dramatically since its infancy in the early 1970s. Today, it is a high-accuracy, custody-transfer grade method of liquid and gas flow measurement.
Ultrasonic flowmeters use no moving parts, offer very low pressure drop and do not require regular calibrations. They use transit time principles to measure the difference in travel time between ultrasonic pulses (beams) transmitted across the pipe at an angle, in the direction of, and against the flow. This travel time difference is proportional to the volumetric flow rate.
Sensor constructions featuring a single beam or multiple beams through the center of the pipe have been subject to flow profile effects. Multiple beam inline transit time ultrasonic flowmeters, with five, and recently also with three beams, caused a major breakthrough in accurate flow metering. Viscosity or flow profile dependence is gradually eliminated to zero as the number of beams is increased. Beam placement and flowmeter characterization by means of wet factory calibration are also important factors for the accuracy enhancement.
As a result of technological improvements, the American Gas Association approved the use of multibeam ultrasonic meters for custody transfer of natural gas in 1998. Early last year, the American Petroleum Institute released a draft standard approving the use of transit time meters for custody transfer of liquid hydrocarbons. While strong demand for ultrasonic flowmeters exists in custody transfer applications, savvy flowmeter users are becoming aware of the advantages for reliable process use. The total cost of ownership (TCO) and return on investment (ROI) for these meters often look good, considering the superior performance, low maintenance and longevity of ultrasonics.
Recently, Krohne introduced a new inline, three-beam ultrasonic flowmeter with high accuracy and repeatability and a competitive TCO and ROI. However, TCO and ROI for a flowmeter purchase are complex to calculate and unique to each application. TCO takes into account initial pricing, maintenance and operation costs over the flowmeter’s lifetime. ROI gives an indication of the impact of the investment on the bottom line.
How to choose
Important points to consider when you are choosing your flowmeter technology are:
Accuracy—Accuracy is serious business and comes with a price tag attached to it. Too much accuracy is costly; too little can save on initial investment, but can have enormous costs associated with it if safety, product quality or yield are compromised.
Operating and maintenance costs—Ultrasonic meters have low operating costs because there is negligible pressure drop and no filters are required. Maintenance costs are low because there are no moving parts and recalibrations are not required. Using a standard flowmeter throughout the plant reduces spare stock holdings.
Longevity—The ultrasonic meter’s design, with robust construction and no moving parts, can survive in challenging applications for a very long lifetime. Krohne sold its first ultrasonic meter to a major oil company in 1980, and it is still in use today.
Reliability—Multibeam ultrasonic meters provide built-in sensor redundancy and advanced diagnostics to assure high reliability.
Liesel Oliveira,[email protected], is a M. Sc. Ch. E. and follows flow and level measurement market trends for KROHNE.
