These are two centrifuges used onboard ships to separate two liquids with different densities from one another in the case of purifiers or to separate impurities from water in the case of clarifiers.
They contain discs stacked up together numbering 150, separated from each other by a very small gap. A series of holes bored on each disc are aligned near the outside edge which permits entry of dirty oil. Due to the difference in gravity and centrifugal force, the heavier impure liquid ( water) and particles move outside and lighter clean oil flows in and gets separated. The collected sludge can be discharged continuously or at time intervals depending on the construction, automation or system built with the purifier.
Purifiers extend the life of the engines and other machinery by retaining the efficiency of lubrication of the oil. This reduces wear of the machinery, improve energy use, reduce maintenance and downtime and lowers the demand for new lubricating oil which reduces cost for the ship owners.
Differences between purifiers and clarifiers.
Purifiers are used to separate oil from water,can also separate solid particles while clarifiers separate only finer or solid particles from oil.
Purifiers have gravity disc which works on the principle of gravity, while clarifiers have discharge collar a which work on the principle of centrifugal action.
In purifiers the lower disc has holes, while the lower disc in clarifiers have no holes.
Purifiers have disc without neck but clarifiers have disc with small neck.
Purifiers are with automatic cleaning arrangement but clarifiers have to be cleaned manually.
In a purifier before introducing the oil, water sealing is established so that oil fill should not flow out through the heavy liquid outlet while in clarifiers there is no heavy liquid outlet for discharging separated water hence water sealing is necessary.