Faced with less time and personnel to devote to an increas- ing range of control and measurement problems, engineers must often weigh the cost of inaccuracy against the initial and maintenance costs of flowmeters. This demand for higher accuracy and lower cost over the lifetime of the device is driving the development of enhanced functionality.
Most of the recent innovations in flowmeter technology are related to mass measurement. The developing trend is a result of a growing awareness of the need to measure mass flow, and a critical understanding of the variables that can affect an instrument's specified accuracy.
The trend to replace orifice meters and other differential pressure producing devices is an example of how both of these influences are at work. The orifice plate and differential pressure transmitter still dominate the flow measurement market and are perceived to be the lowest-cost solution. How- ever, recent studies show that this technology is rapidly losing market share.
The single biggest weakness of the differential pressure meter is turndown. All flowmeter accuracy statements are based on a specified operating range. A flowmeter's operating or turndown range can vary depending on the technology. Given the opportunity, most engi- neering professionals will specify a device with wider turndown to improve the measurement's accuracy.