CATCH 3639351 - Caterpillar

In selecting the cooling system it is desirable to maximize performance, reliability, serviceability, efficiency and engine life while minimizing initial investment and operation and maintenance costs.There are two types of heat exchanging systems recommended for use with Caterpillar Diesel Marine Engines. These involve the use of either inboard-mounted heat exchangers or outboard-mounted keel coolers.Heat Exchanger
* Maximum cooling for size and weight.* Minimum hull resistance.* Compactness* Small expansion tank required.* Unaffected by still water.* Can be maintained inside vessel.* Higher initial cost.* Additional pump required.* May be adversely affected by debris or silt in the water.* Care and precautions required in bringing raw water into the vessel.Keel Cooling
* Simple, single coolant path.* Simple rugged construction of fabricated keel cooler.* Easy installation of packaged keel cooler.* Relatively unaffected by dirt or debris in the water.* Lower maintenance costs.* Lower initial cost.* Only one pump is normally required.* Low efficiency in still water.* Significant drag at higher vessel speed.* Requires larger capacity expansion tank installation.* Keel cooler maintenance or cleaning can require dry docking.Expansion Tanks
Expansion tanks have several important functions:* Vent gases in the coolant to reduce corrosion and to prevent loss of coolant due to displacement by gases.* Provide a positive head on the system to prevent cavitation.* Provide expansion volume and to prevent coolant loss when the coolant expands due to temperature change.* Provide a place to fill the system, monitor its level and maintain its corrosion-inhibiting chemical additives.Deaerator
A deaerator is a device to separate gas bubbles from engine coolant in the absence of or in conjunction with a factory designed, engine mounted expansion tank. It is mounted in series, in the mainflow of jacket water between the engine and its heat exchanger. In the absence of a factory designed, engine mounted expansion tank, a simple volume chamber is required to handle coolant expansion and to vent the separated gas bubbles to the atmosphere. A deaerator and volume chamber can be used in place of an engine mounted expansion tank.A simple volume chamber can fulfill all the functions of an expansion tank except to separate the entrained gas bubbles from the coolant. The coolant flow through the volume chamber is minimal and not sufficient to separate the bubbles thus the need for a deaerator.The volume chamber should be installed a few [meters (feet)] higher than and connected to the jacket water pump by a continuously upward sloping stand pipe.The 3406 marine propulsion engine has a deaerator, as standard equipment, incorporated into the temperature regulator housing.