Page 10 - Coolant - Houghton Training

The Mechanics of Metalworking Fluids

Remove the Oil Layer
This layer is what seals off the air supply to the sump and provides nutrients for the

bacteria. By keeping oxygen from the coolant, anaerobic bacteria will thrive. These

types of bacteria are more dangerous to the chemical components of the coolant than
any other types. The oil acts as their food source and they combine with it to create a

biofilm, which forms somewhat of a skin on the surface. These biofilms are difficult to

remove, and once they are formed, only lead to contamination of the entire machine.

The simplest method to remove floating oils are a variety of mechanical skimmers,

which mount to the sump, pull off the oil layer with some type of media (disk, belt, or
tube), and drain it to a collection container. Some of this variety are also equipped with

a mini separation tank so there is no wasted coolant, as it may be picked up during the

process since most coolant contains some mineral oil. There are also coalescers, which

pull the oil off via a collection apparatus, and transfer it to a drum or tank for
separation. The de-oiled coolant then is introduced back the sump. This type of unit is

the best type, since it requires very little maintenance and keeps the fluid in circulation.

Some of this variety also incorporate additional aeration devices and can filter small
floating particulates