All About Venturi Systems

How Does A Venturi System Work?

A Venturi System reduces pressure when a fluid flows through a constricted section (or choke) of a pipe. In 1797, Giovanni Battista Venturi performed experiments on flow in a cone-shaped tube and built the first flowmeter for closed pipes called the "Venturi tube." A Venturi vacuum is created by a pump with compressed air running through it, yet the pump has no moving parts. Compressed air runs through the initial chamber, then a smaller portal that opens into another larger chamber, which is like the first one.

Constricting a pipe where fluid flows through results in lower pressure. This principle is counter-intuitive to common sense. Why does the pressure decrease? Where does the fluid go if the pathway is constricted? When fluid starts to flow, its velocity around the orifice in the pipe increases significantly because of the restriction in the cross-section. An illustration of this is water flowing through a pipe. Water is a liquid that is not easily compressed. When the water flows through the constricted region of a pipe, the water flows faster. The same volume of water must pass through the same space quicker. The smaller the constricted region of the pipe is compared to the original radius, the faster the speed of the fluid.

The faster the moving fluid, the lower the pressure (i.e., Bernoulli's principle), and the higher the velocity, the greater the difference in differential pressure measured. Abrupt restrictions generate severe turbulence in a fluid. Adding a nozzle that is suited for higher flow velocities to fluids with abrasive particles will reduce turbulence and creates less pressure loss. Turbulence reduction is greater with Venturi nozzles and tubes where the restriction is created by longer, conical constrictions in the pipe wall.

All Venturi systems, including gauges, meters, nozzles, orifice plates, chokes, and pipes can be supplied with different restriction diameter sizes so that the pressure loss and differential pressure generated can be optimized for the process conditions and applications. In fluid dynamics, an incompressible fluid's velocity must increase as it passes through a constriction in accordance with the principle of mass continuity, while its static pressure must decrease in accordance with the principle of conservation of mechanical energy. Therefore, any gain in fluid kinetic energy and velocity as it flows through a restriction is balanced by a drop in pressure.

Advantages of A Venturi System

The best advantages of a Venturi Vacuum System is that it:

• Creates a high vacuum and amplified flow to generate a strong conveying force to move any material with ease.
• Reduces energy costs with less air consumption and uses less pressure.
• Less likely to contaminate airflow because of the straight-through design, which prevents clogging.
• Lightweight and portable; Simple configuration, which is easier to manufacture and less expensive to purchase. Quickly and easily assembled and attaches to an existing configuration. Has no valves and requires no filters.
• Configurable: Standard, Threaded (NPT or BSP) or Flanged connection
• Available in a wide choice of materials: Anodized/hard anodized Aluminum, 304/316L stainless steel, and Teflon. Built to last: materials are treated to ensure longevity in the product's life cycle
• Exceeds multi-stage pumps by 2 to7 times
• No electrical or explosion hazard

Venturi System Applications

Venturi tubes are used in processes where permanent pressure loss is not tolerable and where maximum accuracy is needed in case of highly viscous liquids. It is also used in applications where they replace electrically powered vacuum pumps:

• Gas venting
• Moving metal parts in a machinery rough environment:
  • Hopper loading; Plastic pellets for injection molding
  • Trim Removal
  • Filling operations
  • Material Transfer
  • Sandblasting
• Gas through a transmission line or scrubber: Moves wet and dry material or fluid through a pipe
• Energy Transmission: Transporting solvents and chemicals, for example, oil and gas, steam
• Convert a standard air compressor into a suction machine to secure products with a uniform suction to secure a base to a surface. Using an air compressor as a clamping force also prevents the need for holes on a work surface.
• Measure the speed of a fluid, by measuring pressure changes at different segments of the device:
  • Measure fuel or combustion pressures in jet or rocket engines
  • Measure small and large flows of water and wastewater
• In metrology (science of measurement) for gauges calibrated for differential pressures.
• Water aspirators that produce a partial vacuum using the kinetic energy from the faucet water pressure
• Connect your vacuum bag to make vacu-formed laminates
• Vacuum forming operations for efficient industrial applications
• Atomizers that disperse perfume or spray paint (i.e., from a spray gun).