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Tech-articleWater efficiency in tank cleaning

Often one of the most important factors in tank cleaning is the amount of water used in the process. The true cost of inefficient water usage in tank cleaning is often underestimated.

The true cost of water

- Raw utility bill cost per m3            

- Cost of filtering and sanitising if recycling wash off

- Cost of caustics, solvents or other cleaning fluids

On top of this if the water needed to clean a tank is reduced money can also be saved in the following ways.

- Lower Pump running costs (electricity)

- Lower Maintenance cost

- Increase working lifetime for the pump.

-Potentially use a smaller pump (reduced capex)

Not only does all this represent a significant financial cost the environmental cost of water waste is also high. With tougher and tougher environmental legislation coming into force each year the drive to reduce water consumption in tank cleaning is getting stronger. 

Reducing water consumption

The choice of tank cleaning system can significantly reduce the amount of water used. The most efficient tank cleaners rely on the impact of the cleaning fluid on the tank surface rather than the ability of water to dissolve residue. This mechanical action is far more effective per litres of cleaning fluid used. So increasing the impact of the cleaning system will almost always improved efficiency.

Tank cleaner selection

Static nozzle systems produce relatively little impact and so are the least efficient in terms of cleaning power per litre of fluid used. They reply almost entirely on the dissolving / cleaning action of the water itself rather than the mechanical action of the spray impacting on the tank wall.

Rotary fan nozzle systems produce medium impact fan jets of fluid which sweep the tank walls. This sweeping action delivers vastly more mechanical energy to the cleaning process. As such far less water is required to achieve the same level of cleaning when compared to static nozzle systems.

Rotary jet or impingement cleaners produce high impact jets and so deliver maximum impact. These jets explode outwards as they hit the surface and will dislodge even very tough residues. This high mechanical action cleaning is the most water efficient.

Pressure

The pressure at which the tank cleaning system is run can also have a big impact on efficiency. As a general rule higher pressure systems will produce higher impact sprays and jets. They will also require higher flow rates and hence use more water per minute. At the same time though improved impact can reduce the overall cleaning time required and thus reduce overall water consumption. In many cases the reduced cleaning time effect can be greater than the effects of increased flow rates and thus an overall efficiency gain is made.

This phenomena is less true for static and rotary fan systems but for rotary jet cleaners operating them at higher pressures improves overall water consumption significantly. For fluid powered rotary jet systems like the Orbitor and Storm Blasters the optimum pressure is normally around 8 – 10 bar.

Tech-articleMore details

For a more in depth discussion of efficient tank cleaning please refer to the technical article linked in the icon.

Tank Washing Engineering Considerations

Tank Washing Nozzle Designs

Tank Wash Nozzle Selection Table