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Vortex flowmeters eliminate low-flow problems

Supplier: Endress+Hauser Australia

Steam is an essential process ingredient across a wide range of process industries, from power generation, food and beverage, chemicals to paper and pulp. Increasingly, in most process plants and utilities, steam is supplied by specialist third-party providers. The accurate and reliable measurement of steam is therefore critical to a plant’s cost-effectiveness.


The most common meter used in such measurements is based on vortex technology and these are largely calibration-free, robust and reliable – such as the Endress+Hauser Proline Prowirl 72/73 flowmeters.

There is, however, an inherent shortcoming associated with applying vortex technology as a generic replacement for orifice plate installations measuring steam, but also gases and non-conductive liquids.  This is the low-flow cut-off inherent to all vortex flowmeters which prevents them from accurately measuring flows below a certain level. The common solution for low flowrates in bigger pipes to date has been to use vortex flowmeters in conjunction with reduction piping – a combination of reducers, straight piping and expanders. Such an installation improves the meter’s performance in the low-flow region because it increases velocity locally within the reduced piping section, but adds complexity, pressure drop and cost.

Endress+Hauser has overcome this disadvantage with the launch of its Prowirl R Style and S Style vortex flowmeters that include a reduction by one or even two line sizes inside a single device – with the same flange-to-flange length as a standard meter. With an integrated reduction of line size in a single, simple device, Proline Prowirl 72F and 73F completely eliminate the need for reducers and expanders. Their increased measuring capabilities in the low flow range are accompanied by significant time and cost saving.

Moreover, if the vortex flowmeter was not sized correctly during the engineering process, it can be easily replaced by another one that suits the application and matches customer’s piping. Endress+Hauser’s new vortex flowmeters offer the largest dynamic measurement range (minimum-maximum) and are offered in the broadest variety available in the market. Prowirl 72FR and 73FR reduce the line size by one size, ie DN50 to DN40 and Prowirl 72FS and 73FS reduce the line size by two sizes, DN50 to DN25, for example.

Endress+Hauser’s ruggedly-designed flowmeters can withstand high levels of vibration – up to 1G in all axes. Prowirl 73’s robust construction ensures it can withstand temperature shocks up to 150 K/s. It also has a high resistance to clogging fluids and has full resilience to the water hammer problems associated with steam applications.

Prowirl 73 can accurately measure the volume or mass flow of saturated steam, compressed air, gas and liquids. It directly measures volumetric flow and temperature without the need for an additional thermometer and flow computer. In situations where the pressure fluctuates, Prowirl 73 is able to digitally read in a pressure value using HART, Profibus PA or Foundation Fieldbus – without a loss in accuracy that is usually associated with analogue wiring.

Being a two-wire instrument without the need for any additional power supply or wiring, Prowirl 73 can be easily installed. Additionally, when used with non-abrasive fluids, Endress+Hauser assure the “life-time” calibration of the device. This concept of fit-and-forget ensures a low cost of ownership.