What method should be used to warm up pump turbines prior to discharge?

To warm up pump turbines prior to discharge, the best method is to shut the discharge valve and run the pump at slow speed. This approach allows for a controlled increase in temperature without subjecting the turbine to excessive strain or thermal shock. By running at slow speed, the lubrication system can effectively provide sufficient lubricant to the bearings and other moving parts, preventing potential damage due to cold starts.

This method also ensures that the internal components of the pump and turbine reach an even temperature gradually. If the discharge valve were to remain open or if high speeds were used, it could lead to inefficient operation or even mechanical failure, as the components would face sudden temperature changes or stresses that they are not designed to handle.

Using other methods, such as connecting the turbine while it is locked or attempting to warm it through high-speed operation, could lead to improper functioning or safety risks, including equipment damage and inadequate lubrication. Therefore, the option of shutting the discharge valve and operating the pump at a slow speed is a best practice that promotes safe and efficient operations.