Repair work at the Hammanskraal Drinking Water Project in Tshwane, South Africa, has included replacement of the lower bearing on an Archimedes screw with a Vesconite Hilube polymer bearing.
The bearing has a 202 mm inner diameter, a 300 mm outer diameter and is 407 mm long. The bottom bearing shaft with the hub and base plate weighed 723kg.
It formed part of a turnkey design and manufacturing project to redesign the screw pumps in a project contracted to the Shosalowe Inv / Wamechsi Group.
Vesconite Hilube was chosen because the application is submerged, and Vesconite Hilube does not swell in water. It was also specified in this potable water application since self-lubricating Vesconite Hilube does not require grease, which can be hazardous to human health if consumed, and it is certified for potable water and food contact applications.
Chris Fourie, of Atlas Lifting Equipment, carried out the maintenance on the Archimedes screw between December 2020 and January 2021.
Fourie tends to use phosphor brass or greased eco-bearings for raw sewerage Archimedes screw applications, but specifies Vesconite Hilube for potable water applications.
He will continue to use Vesconite Hilube for the Hammanskraal lower bearings, and envisages that replacement will take place every two years at this plant that operates 24 hours a day and seven days a week.
The Hammanskraal Drinking Water Project’s Archimedes screws were installed in 2017, have a length of 12.6 m, a diameter of 2 m and the screw body weighs 7.6 tons. Powered by a 90 kW motor, it runs at 47 rpm.
It is regarded as important since it is self-regulating, pumping less when the water level is lower and more when the water level is higher.