Flowplate:_Market_Research_about_Primary

Once the value of these devices is taken into account, it should be possible to give an accurate value for the size of the DP flowmeter market.

The Importance of Primary Elements

Primary elements are an important part of the picture, not only because of their cost, but also because they greatly add to the versatility of DP flow measurement. There are many different types of orifice plates, for example, that have different shaped orifices with different locations. Flow nozzles are widely used for steam flow measurement. And Venture tubes are suited for measuring high-speed gas flows, especially in the larger pipe sizes.

Anyone who wants to understand DP flow measurement should be aware of the different types of primary elements available, and should also be aware of the advantages and disadvantages of each. The table below gives a summary of the main types of primary elements, their applications, and their advantages and disadvantages.

Taking a New Look at DP Flow

DP flow is important because of its large installed base, its versatility, and because it is one of the most studied and best understood flow technologies. DP flowmeters can be used to measure gas, steam, and liquid flows. They have been around for more than 100 years, and have been studied by groups such as the American Gas Association and the American Petroleum Institute. While some DP flowmeters are being replaced by new-technology meters, customers who prefer to stay with the tried and true are continuing to order DP flowmeters. And companies such as Emerson Rosemount, Honeywell, Foxboro, Siemens, ABB, and others are continuing to bring out new and improved pressure transmitters.

Coming to a full appreciation of the true value of the DP flowmeter market will provide a more realistic understanding of where end-users are spending their flowmeter dollars. And it will provide a better understanding of how DP flow stacks up against competing flowmeter types, both new-technology and traditional technology flowmeters.

Flowmeter Type	Liquid, Steam, or Gas	Line Size	Advantages	Disadvantages	Comment
DP-Orifice Plate	Liquid, Steam, Gas	½ inch and up	Low purchase price; Easy to install; Well understood; Industry approvals	Limited rangeability; Creates permanent pressure drop; Uses square root method to calculate flowrate	Most traditional meter
DP-Venturi Tube	Liquid, Gas	2-30 inches	Cam be used for both clean and dirty liquids;	Can be difficult to install due to size	Larger sizes for gas
DP-Pitot Tube	Liquid, Gas	> 1 inch	Low cost; Very little pressure drop	Low accuracy; Limited sampling of flowrate	Measures flow only at one point
DP-Averaging Pitot Tube	Liquid, Gas	> 1 inch	Higher accuracy than single Pitot tube; Virtually no pressure drop	Limited rangeability; Not designed for dirty fluids	Also available as Annubar
DP Flow Nozzle	Steam	2-30 inches	Handles high velocity fluids well; Performs better with dirty fluids better than orifice plate	High purchase price; Not easily removed for inspection and cleaning	Widely used for steam flow measurement

The DP Flowmeter Market

The Importance of Primary Elements

Taking a New Look at DP Flow