Tank cleaning applications can be adversely affected by pressure loss problems which can have a direct impact on cleaning efficiency. A good example of this is where cleaning heads were installed and then subsequently found to be having very little impact on the tank walls. The tanks in question were large 10 meter diameter storage vessels that required periodic, as opposed to regular cleaning. In theory the 4 nozzle rotary jet heads should have had sufficient reach to provide adequate cleaning but, when observed, the jets were barley reaching the walls.
Following the investigation it was found that frictional pressure losses were causing a significant pressure drop between the pump and the cleaning head. The pipe run was quite long with an effective length of 50 meters and in addition, there was a 12 meter climb. Also, the tanks were larger than before so a natural conclusion would be that a larger tank cleaning system would be needed. However, what was not accounted for was the additional flow in the existing pipework, which then caused an increase in pressure losses. The result was that the cleaning heads only ‘saw’ a 4 bar pressure drop, as opposed to the 8 bar required.
As the cleaning required on this particular application was only periodic the time taken to clean was not critical. Therefore, swapping the cleaning heads from a 4 nozzle to a 2 nozzle configuration meant that the cleaning time was doubled, but crucially the flow rate was lowered. This reduced the frictional pressure losses incurred and allowed the new 2 nozzle configuration to ‘see’ the higher pressure drop and therefore, delivered a more powerful cleaning jet.
This relatively simple reconfiguration meant that the time, expense and inconvenience of having to upgrade existing pipework was avoided and enabled the existing tank cleaning system to deliver the higher flows required for more effective cleaning.