Page 237 - Bluebook Sereco english

Lifting units

• PVA
• AL www.sereco.it

In several points of a plant for the treatment of civil or ticular characteristic of flow self-adjustment accord-
industrial waste water it is necessary to lift more or less ing to the water level in the suction well.
considerable quantities of sewage. Moreover the lift- The air-lift (AL) pumps are instead used prevalently for
ing units often absorb most of the total energy required the lifting of water and sand or water and sludge mix-
by the plant. It is therefore more and more necessary tures from the sand remover or clarifiers bottom. They
to maximize the relevant hydraulic efficiency. have to be preferred to the standard centrifugal pumps
SERECO catalogue offers, as lifting units, two mod- for their easy operation, absence of mechanical mov-
els symbolizing the whole category: the Archimedean ing parts in contact with the fluid to be lifted and
screw pump (PVA) typical for the lifting of very high therefore extreme reliability, flow clearance that prac-
flow rates and the air-lift (AL) used for the lifting of tically coincides with the delivery piping cross section.
fluids full of sands or suspended solids. Both lifting units require a tailored design from time to
The Archimedean screw pump plants (PVA) are gener- time in order to maximize the hydraulic efficiency. Just
ally used at the inlet or at the intermediate stages of for this reason the dimensions proposed in the data sheets
the plant, for the lifting of the whole inflow and/or for are only indicative and approximate and do not absolute-
the sludge recycle and transfer. They shall be preferred ly cover the whole range of the available products.
to the standard centrifugal pumps due to the very large We wish also to remind you that, on request, SERECO
flow clearance which makes the clogging practically can also design specific lifting plants with centrifugal
impossible, the high hydraulic efficiency and the par- pumps.