Tank eductor placement should create a continuous bulk-flow path through the working liquid while maintaining submergence, avoiding wall impingement and keeping the discharge away from the recirculation suction. Quantity alone does not determine mixing quality. The same eductors can perform very differently when their elevation, angle or direction changes.
Use a plan view and an elevation view for minimum, normal and maximum liquid levels. Show every coil, baffle, column, suction, return and instrument that can interrupt the jet.
Five placement principles
- Sweep the process volume. Aim jets through the largest useful liquid path, not merely across the nearest open space.
- Keep suction and discharge separated. Direct return flow away from the pump suction to reduce local short-circuiting.
- Work around internals. Coils and baffles can create isolated compartments that need their own flow path.
- Maintain access. Units, strainers and header branches need inspection and removal space.
- Check every operating level. A fixed layout must remain submerged and useful from minimum to maximum level.
The selected model’s effective flow-field data provides a starting envelope. It does not replace a tank-specific layout review.
How should an eductor be oriented?
Orientation should support both horizontal circulation and vertical exchange. A purely horizontal ring may leave top-to-bottom stratification in a tall tank; an excessively upward jet may disturb the surface or entrain air. A downward jet can help bottom sweeping but may increase erosion or disturb settled material that should remain undisturbed.
| Orientation | Potential use | Check |
|---|---|---|
| Tangential | Develops circumferential circulation in round tanks | Confirm the centre and upper volume do not become weak zones. |
| Across the diameter | Sweeps through the centre | Avoid direct collision between opposing jets. |
| Slightly upward | Promotes vertical exchange | Maintain submergence and avoid surface vortexing or air entrainment. |
| Slightly downward | Supports bottom movement or selected suspension duty | Review erosion, solids properties and floor clearance. |
Use adjustable mounting only when the connection and mechanical design are suitable for the operating load. Record the final angle so maintenance does not change the validated configuration.
Submergence and changing liquid levels
The eductor inlet region must remain surrounded by liquid for the intended operating condition. If the liquid level approaches the device or its induced-flow openings, circulation and air entrainment behavior can change. Check the lowest credible level, including startup, shutdown and batch transfer.
Tall tanks
Review whether one elevation can exchange the entire vertical column. Multiple elevations or a deliberate vertical component may be required, but each branch changes header loss and pump demand.
Rectangular tanks
Long tanks often need staged flow paths rather than a single circular pattern. Aim successive units so liquid moves through each zone without two jets cancelling one another.
Tanks with coils or baffles
Treat major internals as flow boundaries. Place and aim units so liquid crosses between zones where openings permit it, or provide separate circulation within each zone.
Common layout patterns
Single-direction loop
Several units reinforce one circulation direction around a round or open tank. It is simple, but the centre and vertical column still need evaluation.
Zoned sweep
Units are assigned to separate tank regions divided by geometry or internals. This is useful for long tanks and coil banks, provided branch pressures are balanced.
Multi-elevation layout
Lower units move bottom liquid while upper units support vertical uniformity. Confirm the minimum level and do not assume equal branch flow when elevations and pipe lengths differ.
Use the quantity calculation together with the layout. The required number is whichever is greater: circulation demand or geometric coverage.
How to verify placement during commissioning
- Measure pressure at representative header locations.
- Confirm every eductor is submerged and unobstructed.
- Observe surface movement without treating surface motion as proof of complete mixing.
- Use concentration, conductivity, temperature or another process-relevant measurement at several locations and elevations.
- Record pump operating data, valve positions and liquid level.
- Document final angles and any field adjustments.
If a zone remains slow, investigate header imbalance, blocked passages, wrong orientation, short-circuiting or insufficient motive pressure before adding units.
Continue with tank eductor troubleshooting and pump sizing.
Review the Mixing Eductor commercial hub or send your plan and elevation drawings for a layout review.
Technical reference
For the importance of model, size, material, specification and installation differences, see Spraying Systems Co.’s guide to optimizing in-tank agitation with eductors. Final placement must be checked against the selected model documentation.