A hydraulic sand ejector used in slow-sand-filter maintenance combines a top sand feed, pressure-water nozzle, sand-and-water outlet and a separate perforated irrigating-water pipe inside a portable ejector box.
Hydraulic Sand Ejector Interactive Calculator
Explore the flow paths and convert entered pressure and diameter into reference units. No slurry capacity is predicted.
Equation Used
- Entered pressure is converted as a static pressure magnitude, not a measured nozzle operating state.
- Freshwater density is fixed at 1000 kg/m³ for the equivalent-head tile.
- Area is the circular area corresponding to entered diameter, not verified nozzle or throat area.
- No nozzle/throat ratio, motive flow, suction, entrainment, slurry concentration, particle size, lift, discharge backpressure, loss, erosion, blockage, equipment rating or safety model.
The numerical results describe unit conversions and circular geometry. They do not determine how much sand an ejector can move.
Flow paths through the ejector box
Sand enters from above. Pressure water enters the ejector nozzle from the side and the combined sand-water stream leaves through the discharge. A lower perforated pipe supplies separate irrigating water to help feed material toward the ejector.
Historical filtration-plant context
The cited slow-sand-filtration text presents the device for moving filter sand to washing equipment. This page identifies that arrangement without claiming a capacity or operating envelope.
Reference conversions only
Pressure converts by 1 bar=100 kPa. Equivalent static freshwater head is h=P/(rho g), using rho=1000 kg/m³ and g=9.80665 m/s². Entered diameter converts from millimetres to metres, and its circular reference area is piD²/4.
Worked conversion example
At 7 bar, pressure is 700 kPa and corresponds to about 71.38 m of static freshwater head. A 100 mm diameter is 0.100 m and has a circular reference area of 78.54 cm². These are conversions, not ejector performance.
Reference arrangement and calculation limits
The arrangement is shown in Figure 4.8, on page 59, of Slow Sand Filtration from TU Delft OpenCourseWare. A real ejector requires verified nozzle and throat dimensions, motive-water flow and pressure at the device, suction geometry, particle distribution and concentration, discharge line and backpressure, performance maps, erosion and blockage assessment, structure and qualified process design.
Frequently asked questions
Does 7 bar imply a slurry flow rate?
No. Pressure alone cannot determine motive-water flow, suction flow or solids capacity.
Is the entered diameter the nozzle diameter?
The calculator treats it as a reference circle diameter. It is not assigned to a particular nozzle or throat; the area result therefore does not establish a flow area for an ejector.
Can the diagram be used to build or operate an ejector?
No. It illustrates flow paths and does not provide construction dimensions or operating specifications.
Reference
TU Delft OpenCourseWare, Slow Sand Filtration, section 4.2, Figure 4.8 and pages 59–60, describes a portable sand ejector used in filter-sand handling. The pressure, head, diameter and area results on this page are unit and geometry conversions, separate from ejector performance.
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