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EMCO Venturi Nozzles Series VES

EMCO venturi nozzles and venturi tubes have specific uses and are often used as primary elements in flow measurement of steam, air, liquid, vapor, chemical substances and gas. 

Venturi nozzles and Venturi tubes applies 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 Venturi effect takes its name after the 18th century Italian physicist, Giovanni Battista Venturi, who is the discoverer of the effect, The way it works is in accordance to the differential pressure principal and in accordance with the ISO 5167-3 standard.

Functions And Features

  • Used for flow measurement of steam, liquid, air, water, vapour and gas
  • Highly accurate in measuring flow rate
  • Lowest pressure loss in the family of primary flow elements

The venturi nozzle is available with weld ends or flanged process connection depending on client applications and requirements. Always produced from solid bar the venturi nozzle 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.

EMCO venturi Nozzle, Type VES

Principle:The venturi nozzles are delivered with single pressure tappings or annular ring chamber for minus pressure. 

Images & drawings

EMCO Venturi nozzle with condensing chambers
for steam flow measurement in a vertical pipe line.

 EMCO Venturi nozzle with annular ring chamber for
minus tapping and inlet pipe section.

Dimensions for weld ends, DIN and ANSI flanges

For dimensions of flanges and weld ends, click the product sheet at the top of the page.

Design and calculation standards
ISO 5167-3
DN 65 - DN 500
Pressure rating
PN 10 - 640, 150 - 2500 lbs
β (d/D)
d > 50 mm (ISO 5167-3) or according to process data
Bore (d)
preferred range 0,316 < β < 0,775
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
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
Pressure taps
½” NPT ext., ½” BSP ext., ½” butt weld ends, ½” or ¾” flanged, others on request.
Single pressure tappings or 2x4 tappings each arranged with an external annular ring to equalise the pressure.
Tap lenghts
150 mm, others on request
Tap location
At least 45 degrees apart, for sizes below DN 150. To be stated with order
Technical Data
approx. 1,4 – 1,5 % (according to ISO 5167)
Pressure loss
approx. 15 % of the differential pressure measured
Limits for Reynolds No
15 % of the differential pressure measured
shut-off valves
Condensing chamber for steam flow
Bracings for tapping support
2 x D In- and outlet pipe sections, other lengths on request