The Hazen-Williams formula is used to calculate the friction loss of water in pipes, but it is not designed to directly calculate the pressure loss created by special structures such as tubesettler. Tubesettlers are special products designed to increase water filtration, used in water treatment plants.

The pressure loss created by water passing through the lamella can usually be determined using laboratory tests, simulations or special calculation methods. The flow of water through these structures may behave differently than in pipes due to different geometric (hexagon) features, material properties and flow rates.

The Hazen-Williams formula was developed to calculate the friction loss in the flow of water in simple pipelines. Special calculation methods or tests may be required for such structures to determine the pressure loss caused by different structures or special water treatment equipment. Therefore, it may not be accurate or appropriate to calculate the pressure loss of special structures such as lamella directly with the Hazen-Williams formula. Special design calculations or tests may often be required for such structures.