Compressors in refrigeration systems need sufficient lubrication with appropriate refrigerant oil. Some oil is always carried over with the refrigerant into the refrigeration plant - even the latest compressors cannot avoid this.
To prevent the oil is not causing capacity losses, i.e. blocking heat exchanger surfaces, it needs to be removed from the refrigeration cycle. With the automatic WITT oil management, valuable refrigerant oil is returned from the collection point back to the compressors in a controlled manner. That way it does not need to be manually drained, which is not only time saving, but also prevents accidents related to this kind of maintenance. In addition returning and re-using the oil saves operating costs (maintenance, disposal, refill of oil) and protects the environment.
The WITT oil management is initiated right where the majority of refrigerant oil is collected in the refrigeration system. For ammonia system this is the lowest spot in the surge drum. Since refrigerant oil is insoluble in common ammonia systems and the densities differ (oil is heavier than ammonia) it settles at the bottom of the surge drum. The WITT oil management is also possible with soluble oils, i.e. in CO2 systems.
The WITT BDP oil recovery unit is installed at the lowest point of the ammonia surge drum and collects that way the refrigerant-oil-mixture entering the BDP vessel. With hot gas that is either time-controlled or demand controlled with the optional oil sensor the refrigerant-oil-mixture is pushed to a heat exchanger (WITT DWR). Inside the WITT DWR remaining liquid refrigerant is evaporated. An optional oil filter (WITT OF) at the outlet is making sure only clean oil is returned to the compressor.
In refrigeration systems with multiple compressors it is recommended to use a HDB3 stainless steel oil receiver to collect and distribute the oil to the compressors.
You can find above mentioned optional equipment such as sight glasses, oil filters or oil sensors under Accessories.