From Chemical Engineering License Review, Second Edition

Permanent Pressure Loss

Venturi Permanent pressure loss through venturis depends upon the diameter ratio ? and the discharge cone angle ?. The pressure loss for smaller angles (5 to 7 ) is 10 to 15 percent of the total pressure differential ( P 1 ? P 2). It is 10 to 30 percent for large angles (> 15 ).

Subsonic Flow Nozzles For subsonic flow nozzles, the pressure loss is given by

where ? is the nozzle throat diameter divided by the pipe diameter.

Concentric Circular Nozzles In the case of the concentric circular nozzle,

Example 2-2

A venturimeter is to be installed in a schedule 40, 6-in line to measure the flow of water. The maximum rate is expected to be 800 gpm at 86 F. A 50-inHg manometer is to be used. Specify the throat diameter of the venturi and calculate the power required to operate it. The discharge cone angle is 5 .

Solution. From Eq. (2-14),

C = 0.98 for venturis if N Re > 10,000 (i.e., fully turbulent flow). Assume fully turbulent flow. Then

where D P is the inside diameter of pipe, ft. Squaring both sides, one obtains

Simplifying and solving for D T gives

Use 2.375 in = 0.1979 ft (a standard size). Check the Reynolds number through the throat of the venturi.

This N Re is greater than 10,000 and therefore the flow is in the fully turbulent region. Therefore, the size of...

Products & Services
Flow Transmitters
Flow transmitters provide electrical outputs that are proportional to flow inputs. They use flow meters to measure the flow of liquids and gases.
Jet Pumps
Jet pumps are typically used for drawing water up from a well. These pumps can be used for either shallow or deep well configurations. 
Air Blow Guns
Air blow guns attach to air lines for the manual actuation and/or control of air discharge. They are used primarily for debris removal and purging, non-contact part cleaning and drying, and general laboratory or industrial applications.
Nozzles alter and control the stream or spray pattern of a fluid in a spray coating or dispensing system.
Air Scrubbers, Wet Scrubbers, and Gas Scrubbers
Air scrubbers, wet scrubbers, and gas scrubbers are air pollution control devices that use a high-energy liquid spray to remove aerosol and gaseous pollutants from an air stream. The gases are removed either by absorption or chemical reaction.

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