Overview
The T4 Series Ventilation Control System is similar to the P/T4 system described above, without the engine room pressure sensor input. The T4 Ventilation Control System uses digital technology and provides complete control of both the engine room intake and exhaust fans using temperature sensors. This system is designed for use in vessels using natural draft combustion air inlets that require engine room cooling air in addition to the air required for the machinery.

It may be configured to use intake, exhaust fans or a combination of both to provide engine room cooling.

Automatic Operation
When the main engines are started, the system automatically switches to Auto Mode. The speed of the exhaust fans is automatically controlled based upon 'the temperature of the engine room space. The T4 maintains the engine room operating temperature at or below the engine manufacturers maximum temperature difference (?T) when underway. As temperatures rise and cooling air requirements increase, the fan(s) will automatically respond to the additional airflow demands and increase in speed. By automatically speed controlling the fans, the electrical loads and noise levels are kept to a minimum level based upon the prevailing operating conditions. Upon main engine shut down, the T4 Ventilation Control System will automatically switch the fan operation to the "QUIET RUN™" mode to remove excess heat and cool the engine room. The operator can set the fan speed limit when operating in the "QUIET RUN™" mode so fan sound characteristics never exceed the desired level. When the engine room reaches the user settable engine room temperature value, all fans will shut down. As the engine room temperature rises, the fans will continue to start and stop automatically, thus providing true thermostatic control of the engine room when dockside or when operating generators. When main engines are restarted, the system will then automatically switch to the "AUTO RUN™" mode. Among the features of the T4 fan control system is the automatic fire shutdown feature, which will shut down the fans in the event of an engine room fire.

Manual Mode
In addition to the two automatic modes of operation there is a Manual Mode. The Manual Mode allows the operator to control the fan speed and direction independently for maintenance or unusual situations. This mode of operation is not recommended for use when underway and the main engines are running.

Specifications
T4.pdf