Fox Venturi Products (Fox Valve) has been the leading global supplier of venturi eductors and venturi transport systems for dilute phase pneumatic conveying of powders, pellets, and bulk solids since 1963. Fox Eductors, also referred to as jet pumps, enable the use of low-pressure air (below 14 psig or 1 bar) to be used to move powders, pellets, and bulk solids with no moving parts. These venturi eductor systems can be used to convey product at up to 15 tons per hour over distances up to 500 feet.

Suck away, vent, or remove gas using Fox air-operated vacuum jet ejectors driven with compressed air, N2, or any gas. Vapors to be removed can be hot, explosive, dusty, or corrosive. Fox stock ejectors vent gasses with no moving parts for 24/7 reliability. Stock ejectors in 316SS and PVC, 1/2″ to 4″.

Fox Liquid Eductors are venturi jet pumps that use liquid to create vacuum to mix, blend, or dilute other liquids, dry solids, or gasses into a liquid stream. They are used to replace or eliminate pumps when simple, ultra-reliable liquid mixing is required.

Fox Mini-Eductors are small venturi eductors that use pressurized gases or liquids to generate suction for a variety of sampling, pumping, mixing, or vacuum-generation applications. Fox stocks a broad range of off-the-shelf mini eductors in 316 Stainless, Teflon, CPVC, Monel, Hastello

Liquid-driven venturi jet eductors are used to mix solids into liquids. Powders or pellets can be introduced from:

• Bag Dump or Big Bag Feed to Eductor
• Screw Feeder – for accurate dosing to create required solution
• Vacuum Pick-Up – to suck up powders from totes or drums

Fox Venturi ejectors have been used to eliminate blowers and fans in gas-handling, exhausting, gas dilution, vacuum, and fume removal applications since 1961. With no moving parts, Fox ejectors can provide reliable, maintenance-free gas venting in applications where the alternative of using a blower or fan is both unreliable and unreasonably expensive. This is especially true when handling hot, corrosive, explosive or dust laden gasses and fume. Motive gas can be air, natural gas, N2, H2, steam, argon – or any gas.

Fox Air and Gas venturi ejectors have no moving parts. No shafts, no motor starters, no seals, no maintenance. Their rugged construction and simplicity of design enables operation in corrosive, dusty, or high temperature environments.

Ejectors eliminate the need for blowers or fans with XP motors, Teflon-coated blades, or other very expensive blower options that add enormously to cost but still don’t protect your process from intermittent failure.

Many ejector applications do not require use of compressed air at 50-100 psig to accomplish the needed fume or vapor venting – although the ejector can always be designed to use an existing compressed air supply. For continuously operating air ejectors that must vent or exhaust from a process and discharge to a low pressure, a matched blower running at 2 – 3 psig can be provided. This blower can be located far from the corrosive, explosive, or dusty location of the ejector.

If you need 24/7 reliability, lower installed cost, and reduced maintenance, use ejectors for your demanding gas handling applications.

Fox gas ejectors have been engineered and installed in demanding applications in the above industry for 40+ years.

There is no simple rule or equation or chart that is useful for predicting motive flow for air or Nat gas or hydrogen at all temps and all pressures. The best way to get the right answer, fastest, is to complete the Fox Data Sheet datasheet or otherwise describe the pressures, temps, and flow rates. We can then input into our proprietary computer algorithms that will predict performance, motive flow, etc.

Fox has a large inventory of stock air ejectors that are stored both assembled and unassembled, in line sizes from 1/2” to 6” in carbon steel, stainless, and PVC (to 3” only). If your application has a low discharge pressure, the chances are good that components of stock ejectors can be quickly modified to become an optimized venturi jet for your specific application – and can ship in a week or less. Completely custom ejectors, for deep vacuum or higher discharge pressures may require 4 – 8 weeks – which can often be expedited with a rush premium.

In certain applications, and only when discharging to low pressure, this can work over a limited range. However, as a general rule it is always best to maintain a constant MOTIVE gas flow rate and adjust the suction gas flow with a dedicated valve on the suction line.

Most applications need to simply vent or exhaust vapours. The maximum vacuum level – at the no-flow or shut-off condition – is usually irrelevant. But here is a quick guide with air at 80 – 100 psig, off-the-shelf ejectors can pull down to about 10 psia (or -20” Hg vacuum). Custom built single stage ejectors can reach 2 – 3 psia. Two stage ejectors can reach 1 psia.

Fox ejectors below a 5” line size are machined from bar at our plant in New Jersey. We are not locked into fixed geometries by castings made overseas or anywhere else, and we do not simply thread together stock components. We have complete machining and welding capability in-house, which is why we can usually offer an expedited option for rush projects.

Any ejector that can suck in a large gas flow rate will pull a significant vacuum level if the suction gas flow rate, or suction load, stops. An ejector cannot be designed with a limited shut-off vacuum level. There are various solutions – one easy one is to install a vacuum break valve on the suction line, that opens to bleed in free air, thus protecting the process vessel from vacuum.

Since the motive flow goes through a sonic choke in the ejector nozzle, the motive flow is held constant if motive pressure is constant (use a pressure regulator.) If suction inlet pressure is also fixed (such as atmospheric at 14.7 psia), placing a Fox sonic choke on the suction port of the ejector will establish a fixed suction flow rate. Since both flows are fixed, mixture ration is established. This approach can only be used for fixed, constant flow rates -and will not work to maintain a constant mixture ratio with varying flow rates

Yes – but this approach is only used for limited liquid flow rates – like emptying very small sumps that collect refrigerants, hydraulic oil leaks, fuel.

Yes – in-line gas ejectors are available for certain applications, but they are:

1. a) limited to low discharge pressure applications,
2. b) are significantly less efficient than standard ejectors,
3. c) Are not typically in-stock at Fox Valve, and
4. d) are more expensive that stock ejector.

This is usually a high-cost penalty for avoiding installation of one elbow to accommodate a stock ejector.

Stainless is ok for high gas temps up to about 1200ºF. Inconel is used for gases up to about 1600ºF, and other nickel alloys can be used up to 2000ºF

Fox manufactures a complete line of mini eductors for gas sampling through 1/4” and larger lines.

• Venting Explosive, Corrosive, or Dusty Gasses
• Venting Trucks, Tankers and Railcars
• Extracting Hydrocarbon Vapours
• Purging Gas Pipelines
• Sulphur Fumes and H2S Gas Venting
• Gas Turbine and Rocket Engine Testing
• Back-Up/Emergency Vacuum Source