Jet Pumps for Gas Applications: Versatile Solutions for Gas Handling
Jet pumps designed for gas applications can utilize steam, air, or liquid as their operating medium, offering flexible solutions for various industrial needs.
Typical Applications:
- Gas Exhausting (Continuous Removal): This involves consistently removing gases from an area while maintaining a stable pressure. It’s ideal for continuously recurring gases or fumes, such as smoke from welding or machining operations. This process can also be used for injecting oxygen into a liquid stream. In cases where the gases being removed are undesirable, a reactive motive fluid can sometimes be used to neutralize them.
- Gas Evacuation (Volume Reduction): This application focuses on reducing the pressure within a defined volume or tank by pumping gases down from an initial pressure to a lower final pressure. Sizing is typically determined by the time required to achieve the desired pressure reduction. Examples include purging detrimental gases from a reaction vessel or removing steam from a vessel to enhance operator safety before opening. A common variation is using eductors to prime piping or systems with liquid, which can raise liquid levels to pump intake, prevent dry starts, or establish a siphon.
Benefits of Gas Jet Pumps:
- Improved suction flow and discharge pressure capabilities.
- Specifically designed for gas handling and evacuation.
- A cost-effective solution for general vacuum service.
- Can use steam or air as a motive force to create vacuum levels down to 5 inches Hg Absolute.
- Enhanced performance.
- Available with an investment cast body.
- Standard material is 316 stainless steel with NPT connections.
- Special sizes available with fabricated construction.
- PVC construction is also an option.
How Gas Jet Pumps Work:
Jet pumps (eductors) operate on fundamental principles of fluid dynamics. A high-pressure motive stream, which is a compressible fluid (like gas), is accelerated through a converging-diverging nozzle. This acceleration can cause the gas to exceed the speed of sound. This high-velocity motive fluid then passes into a secondary chamber. Here, the friction between its molecules and those of a secondary gas (the suction fluid) causes the secondary gas to be pumped. Both fluids intimately mix and are then discharged from the eductor.
NCI (uniquely) has more than 50 years of experience with jet pumps and in tank mixing applications. Our tank mixing experience covers both tank mixing eductors and propeller type side entry mixers involving tanks in sizes up to one million barrel (42 million gallons) capacity.
related: how does an eductor work?
There are three connections common to all jet pumps (venturi eductors).
MOTIVE Connection: This connection is where the power for the eductor is generated, by increasing the velocity of the motive fluid. The eductor nozzle in this section takes advantage of the physical properties of the motive fluid. Eductors with liquid motives use a converging nozzle as liquids are not generally compressible. Eductors with gas motives utilize converging-diverging nozzles to achieve maximum benefit from the compressibility of the gas. All nozzles for eductors have smooth flow paths. Flow paths with sudden steps or roughness on these high velocity surfaces cause jet pumps to operate less efficiently.
SUCTION Connection: This connection of the eductor is where the pumping action of the eductor takes place. The motive fluid passes through the suction chamber, entraining the suction fluid as it passes. The friction between the fluids causes the chamber to be evacuated. This allows pressure in the suction vessel to push additional fluid into the suction connection of the jet pump. The high velocity of the motive stream in this section of the eductor directs the combined fluids toward the outlet section of the eductor.
Discharge Connection: As the motive fluid entrains the suction fluid, part of the kinetic energy of the motive fluid is imparted to the suction fluid. This allows the resulting mixture to discharge at an intermediate pressure. The percentage of the motive pressure that can be recovered is dependent upon the ratio of motive flow to suction flow and the amount of suction pressure pulled on the suction port. The mixture then passes through the diverging taper that converts the kinetic energy back to pressure. The combined fluid then leaves the outlet.
General Performance Table
Jet Pumps for Gas
Using Air, Liquid or Steam as Operating Medium| Model | ML/LM | MLE/ELL | SG/GL | GH/HG |
|---|---|---|---|---|
| Operating medium | Liquid | Liquid | Steam, Air | Steam, Air |
| Operating medium pressure range | 20-250 PSIG | 20-250 PSIG | 60-120 PSIG | 20-80 PSIG |
| Maximum Vacuum | 29 IN. HG. | 29 IN. HG. | 24 IN. HG. | 24 IN. HG. |
| Outlet Pressure (PSIG) | 20 | 20 | 12 | 20 |
| Functions | Evac/Exh/Prime | Evac/Exh/Prime | Evac/Exh/Prime | Evac/Exh/Prime |
Jet Pumps for Steam
Using Steam as Operating Medium| Discharge Head Level - Model | Low - SG / GL | High - HG / GH |
|---|---|---|
| Operating Steam Pressure Range | 60-150 PSIG | 35-150 PSIG |
| Oper. Steam Press. to Elevate Liquid 50 FT. | 150 PSIG | 75 PSIG |
| Suction Lift (with Water Temp to 120°F) | to 20 FT. | to 20 FT. |
| Minimum NPSH | 13 FT. | 13 FT. |
Total customer satisfaction comes from the combination of quality products purchased at a reasonable price and delivery quickly and when promised.
Jet Pumps are in stock from 1/2″ up to 3″ sizes. Jet Pumps are stocked in Carbon Steel, 316SS and Bronze. Tanks Eductors are stocked in sizes from 3/8″ up to 3″ in both Carbon Steel and 316SS. We also stock tank eductors in both Polypropylene & PVDF (KYNAR) materials in sizes from 1/4″ thru 1-1/2″.
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