ENGINEMAN 1 & CThe temperature regulator consists of a valveand a thermostatic control unit mounted on thevalve. The thermostatic control unit consists ofa temperature-control element and a controlassembly.The temperature-control element is essentiallytwo sealed chambers consisting of a bellows con-nected by a flexible armored capillary tube to abulb mounted in the engine cooling-waterdischarge line. One chamber is formed by thebellows and cap, which are sealed together at thebottom; the other chamber is in the bulb. Theentire system (except for a small space at the topof the bulb) is filled with a mixture of ether andalcohol which vaporizes at a low temperature.When the bulb is heated, the liquid vaporizes andthe pressure within the bulb increases. This forcesthe liquid out of the bulb and through thecapillary tube to the bellows. As the bellows ismoved down, it operates the valve.The control assembly consists of a spring-loaded mechanical linkage which connects thetemperature-control element to the valve stem.The coil spring in the control assembly providesthe force necessary to balance the force of thevapor pressure inthe temperature-controlelement.Thus, the downward force of the temperature-control element is balanced, at any point, by theupward force of the spring. This permits the valveto be set to hold the temperature of the enginecooling water within the allowed limits.The regulator operates only within thetemperature range marked on the nameplate; itmay be adjusted for any temperature within thisrange. The setting is controlled by the range-adjusting wheel, located under the spring seat. Apointer attached to the spring seat indicates thetemperature setting on a scale which is attachedto the regulator frame. The scale is graduatedfrom 0 to 9, representing the total operating rangeof the regulator.The location of a temperature regulatormay be located in either the seawateror freshwater circuit. In most engines, theregulator is located in the freshwatercircuit.When located in the seawater circuit, theregulator controls the amount of seawater flow-ing through the coolers. As the temperature ofthe freshwater becomes greater than thetemperature for which the regulator is set, theregulator actuates a valve to increase the flow ofseawater through the coolers. On the other hand,when the freshwater temperature is below thetemperature for which the regulator is set, theregulator actuates the valve and decreases the flowof seawater through the coolers.In installations where the regulator is in thefreshwater circuit, water is directed to the coolerwhen the temperature of the water is above themaximum setting of the regulator. After passingthrough the cooler where the temperature of thewater is lowered, the water returns to the suctionside of the freshwater pump to be recirculated.When the temperature of the water is below themaximum setting of the regulator, the waterbypasses the cooler and flows directly to the suc-tion side of the pump. Bypassing the cooler per-mits the water to be recirculated through theengine; in this way, the temperature of the wateris raised to the proper operating level.Regardless of whether the regulator is in thefresh or seawater circuit, the bulb which causesthe regulator to operate is located in thefreshwater discharge line of the engine.Temperature regulators not only control thetemperature of the freshwater but also controlindirectly the temperature of the oil dischargedfrom the lubricating oil cooler. Control of thelubricating oil temperature is possible because thewater (freshwater or saltwater) that is passedthrough the regulator and the freshwater cooleris also the cooling agent for the lubricating oilcooler. When the lubricating oil is cooled byseawater, two temperature regulators are installedin the seawater circuit. The temperature regulatorbulb of the regulator that controls the temperatureof the freshwater is installed in the freshwater cir-cuit; the bulb of the regulator that controls thetemperature of the lubricating oil is installed inthe lubricating oil system.MaintenanceTo allow proper operation of a temperatureregulator, the valve stem must not bind in thestuffing box, but must move freely. The valvestem must be lubricated frequently where it entersthe stuffing box and also around the threadedsleeve used for the manual control. A smallamount of grease should also be used on the bevel3-8
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