ENGINEMAN  1  &  C The temperature regulator consists of a valve and a thermostatic control unit mounted on the valve. The thermostatic control unit consists of a   temperature-control   element   and   a   control assembly. The  temperature-control  element  is  essentially two sealed chambers consisting of a bellows con- nected by a flexible armored capillary tube to a bulb   mounted   in   the   engine   cooling-water discharge  line.  One  chamber  is  formed  by  the bellows and cap, which are sealed together at the bottom; the other chamber is in the bulb. The entire system (except for a small space at the top of the bulb) is filled with a mixture of ether and alcohol which vaporizes at a low temperature. When the bulb is heated, the liquid vaporizes and the pressure within the bulb increases. This forces the   liquid   out   of   the   bulb   and   through   the capillary tube to the bellows. As the bellows is moved down, it operates the valve. The  control  assembly  consists  of  a  spring- loaded mechanical linkage which connects the temperature-control element to the valve stem. The  coil  spring  in  the  control  assembly  provides the force necessary to balance the force of the vapor  pressure  in the   temperature-control element. Thus, the downward force of the temperature- control  element  is  balanced,  at  any  point,  by  the upward force of the spring. This permits the valve to be set to hold the temperature of the engine cooling water within the allowed limits. The   regulator   operates   only   within   the temperature range marked on the nameplate; it may  be  adjusted  for  any  temperature  within  this range.  The  setting  is  controlled  by  the  range- adjusting wheel, located under the spring seat. A pointer attached to the spring seat indicates the temperature setting on a scale which is attached to  the  regulator  frame.  The  scale  is  graduated from 0 to 9, representing the total operating range of the regulator. The   location   of   a   temperature   regulator may   be   located   in   either   the   seawater or  freshwater  circuit.  In  most  engines,  the regulator    is    located    in    the    freshwater circuit. When  located  in  the  seawater  circuit,  the regulator controls the amount of seawater flow- ing through the coolers. As the temperature of the   freshwater   becomes   greater   than   the temperature for which the regulator is set, the regulator actuates a valve to increase the flow of seawater through the coolers. On the other hand, when  the  freshwater  temperature  is  below  the temperature for which the regulator is set, the regulator actuates the valve and decreases the flow of seawater through the coolers. In installations where the regulator is in the freshwater circuit, water is directed to the cooler when the temperature of the water is above the maximum  setting  of  the  regulator.  After  passing through the cooler where the temperature of the water is lowered, the water returns to the suction side of the freshwater pump to be recirculated. When the temperature of the water is below the maximum  setting  of  the  regulator,  the  water bypasses the cooler and flows directly to the suc- tion side of the pump. Bypassing the cooler per- mits  the  water  to  be  recirculated  through  the engine; in this way, the temperature of the water is raised to the proper operating level. Regardless  of  whether  the  regulator  is  in  the fresh or seawater circuit, the bulb which causes the   regulator   to   operate   is   located   in   the freshwater discharge line of the engine. Temperature regulators not only control the temperature of the freshwater but also control indirectly the temperature of the oil discharged from the lubricating oil cooler. Control of the lubricating oil temperature is possible because the water  (freshwater  or  saltwater)  that  is  passed through the regulator and the freshwater cooler is also the cooling agent for the lubricating oil cooler.  When  the  lubricating  oil  is  cooled  by seawater, two temperature regulators are installed in the seawater circuit. The temperature regulator bulb of the regulator that controls the temperature of the freshwater is installed in the freshwater cir- cuit; the bulb of the regulator that controls the temperature of the lubricating oil is installed in the lubricating oil system. Maintenance To allow proper operation of a temperature regulator, the valve stem must not bind in the stuffing box, but must move freely. The valve stem must be lubricated frequently where it enters the  stuffing  box  and  also  around  the  threaded sleeve  used  for  the  manual  control.  A  small amount of grease should also be used on the bevel 3-8