Sentinel Mechanical Engine Protection Systems slow to idle or shut down diesel engines before minor problems cause major damage. By controlling fuel flow, Sentinel Systems protect engines from loss of oil pressure, loss of coolant and high oil and coolant temperatures. A major advantage of the all-mechanical Sentinel System is that you can count on reliability ÷ there are no wires or connections to corrode.
Sentinel Systems are available with two options: a manual remote shutdown override and a light/buzzer warning of imminent shut-down. Temperature and pressure shut-off points can be set within wide limits and various options allow Sentinel Engine Protection Systems to be tailored to an individual vesselâs specifications.

The Basic Engine Protection System

During normal operation, oil pressure from the engine keeps the ball valve in the Sentinel Master Control in the raised position, allowing fuel to flow to the engine. With a loss of oil pressure, the ball valve drops and fuel flow is cut off or reduced, depending on the type of system specified.
When coolant or transmission oil temperature exceeds the setting of the Sentinel Heat Sensor, its seal opens and dumps oil pressure from under the Master Control piston, causing the ball valve to fall and halt the flow of fuel. Set to activate at any temperature from 180°F to 255°F, the Heat Sensor comes with 1/2ä NPTF or 3/8ä NPTF threads.
The Sentinel Coolant Loss Valve is kept closed by the flow pressure of the coolant. Loss of pressure causes the valve to open and dump oil pressure from under the Master Control piston, stopping fuel flow.

Customized Operation

Because the piston design in the Master Control utilizes engine fuel pressure to assist in closing the fuel valve, the Master Control can be closed at a higher working oil pressure than its original low idle setting.
For example, a Sentinel Master Control installed in a Detroit Diesel engine has a primary oil pressure setting of 5 psi for idle conditions. However, when running at governed speed under load, this engine produces approximately 70 psi to 80 psi fuel pressure. Under these conditions, the Sentinel Master Control closes the fuel supply to the engine when diminishing oil pressure reaches 15 psi, not the primary setting of 5 psi.
Temperature and pressure shut-off points can be specified within wide limits and various options allow Sentinel systems to be tailored to individual specifications. Settings can be done at the factory or on the job by the shop mechanic. On suction side applications, the Master Control is installed between the fuel filter and the injection pump. On injection engines, it can be installed between the final filter and the head.