In this method, the engine speed is reduced until the temperature of the exhaust inlet falls below 420 °C. Fresh Water used for washing must be slightly hot and the water is injected through a regulating valve connected to the turbine side.
This is done to avoid thermal shock to the machinery. While performing water washing the drain is kept open. When the water feed is closed the drain is observed until no water comes out.
The engine is run for further 20 minutes with less rpm to dry out the turbine from water. Before increasing the rpm, the drain is shut and any abnormal vibration must be observed.
For Dry-washing carbon granules are used which are injected inside the turbine through a compressed air system.
The engine speed is not reduced as there is no risk of thermal stresses in dry washing.