The EMCO Venturi nozzle is used for flow measurement of steam, liquid, air, water, vapour and gas. Venturi nozzles apply the Venturi effect, which is the limitation of liquid pressure caused by a narrowed section of a pipe when a fluid flows through it. The design and construction of a Venturi nozzle is based on Bernoulli’s principle and a Venturi nozzle is very stable at high temperature and flow rate. The nozzle works in accordance with the differential pressure principle and the ISO 5167-3 standard.
The venturi nozzle is available with weld ends or flanged process connection depending on client applications and requirements. It is well suited for high-pressure steam boiler applications and is often installed in the main steam pipe between the boiler and the steam turbine. It provides accurate flow measurement and induces less permanent pressure loss compared to the ISA1932 flow nozzle.
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Design and calculation standards |
ISO 5167-3 |
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Sizes |
DN 65 - DN 500 |
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Pressure rating |
PN 10 - 640, 150 - 2500 lbs |
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β (d/D) |
d > 50 mm (ISO 5167-3) or according to process data |
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Bore (d) |
Preferred range 0,316 < β < 0,775 |
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Material |
Carbon steel P250GH, AISI 316, 22Cr Duplex, 25Cr Duplex, 6Mo. Heat- resistance steels:16Mo3, 13CrMo4-5, 10CrMo9-10, WB 36, X20CrMoV121, F91, F92, other materials on request |
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Mounting style |
Weld ends according to EN 9692-1 or ANSI B16.25, flange connection according to DIN, ANSI B 16.5, EN 1092, ISO 7005, NORSOK L-005, or hub connection to specific manufacturer´s standard |
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Pressure taps |
½” NPT ext., ½” BSP ext., ½” butt weld ends, ½” or ¾” flanged, others on request. |
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Tappings |
Single pressure tappings or 2x4 tappings each arranged with an external annular ring to equalise the pressure. |
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Tap lenghts |
150 mm, others on request |
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Tap location |
At least 45 degrees apart, for sizes below DN 150. To be stated with order |
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Accuracy |
approx. 1,4 – 1,5 % (according to ISO 5167) |
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Pressure loss |
Approx. 15 % of the differential pressure measured |
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Limits for Reynolds No |
15 % of the differential pressure measured |
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Shut-off valves |
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Condensing chamber unit for steam flow |
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Bracings for tapping support |
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2 x D In- and outlet pipe sections, other lengths on request |
EMCO Venturi nozzle with condensing chambers
for steam flow measurement in a vertical pipe line.
It must be stored carefully to avoid corrosion and damage. Installation requires centering the nozzle in the pipeline and welding it properly. The pressure tappings should be correctly oriented, and impulse lines need to be sloped for air escape. Safety measures are crucial to prevent exceeding the maximum allowable pressure. The nozzle has minimal maintenance requirements but should be free from deposits. With references to ISO 5167, DIN standards, and flow measurement handbooks, the EMCO Venturi nozzle offers accurate flow measurement when installed and maintained correctly.
Download the installation guide above for more detailed information.
EMCO Venturi nozzle with annular ring chamber for
minus tapping and inlet pipe section.
