Temperature Regulators.—Autornatie devices designed to regulate the temperature of the circulating medium in heating apparatus have been used for several years. These devices, however, have not been wholly successful in regulating the temperature of rooms, because they have been actuated by the return water to the heating apparatus, and have been designed to close the damper when the temperature of the return water reached a certain point, As it is desired in heating cars that the return should be, in cold weather, at a much higher tempera ture than in moderate weather, it is evident that the temperature of the return affords no indication of the temperature of the car. Suffice it to say that for car-heating purposes especially, the temperature of the car and not the temperature of the heating, pipes must govern in automatic devices.
Of recent years several devices have been introduced that have gone a step further, and have been so arranged that they are actuated by the temperature of the ear itself. In the line of improvement here indicated, the Johnson regulator has been introduced to a limited extent. This is a device in which a thermostat is used to make electrical contacts; one con tact when the temperature of the ear reaches 72° and an opposite contact when the tempera ture reaches 70°. The electrical contact made at 72° closes the circuit of the battery so as to actuate an eleetro-pneumatie valve, which admits air under pressure from the auxiliary reser voir of the air-brake apparatus to a pneumatic steam-valve. This is an ordinary form of steam valve in which the valve-stem is connected to a diaphragm by means of which the valve is closed by the air pressure above referred to. When the temperature of the car reaches 72°. provided the apparatus has been set for that temperature, the steam is automatically shut off from the car. When the temperature falls to 70°, an opposite contact is made which. oper ating the electro-pneumatic valve in the opposite direction, the air-supply from the auxiliar reservoir is shut off, and the diaphragm of the pneumatic steam-valve is allowed to open, and steam is again admitted to the car.
The Consolidated Car-Ileatiny Co.'s Regulator is a graduated apparatus, and is so arranged that the steain-valre nt all temperatures tel 60' stands wide open. At 60° the valve begins to close, and gradually approaches its seat until the temperature of the car reaches 74°, when the valve is entirely closed. The amount of steam which can pass the steam-valve when the temperature of the car is 65° is about four times as much as is sufficient to maintain an even temperature in the car when once heated up—in other words. steam sufficient to condense to about 295 lbs. of water in one hour's time. At 68° the increase of temperature of the car closes the valve, so that about 150 lbs. of water will condense from the steam which passes this
valve in one hour's time. At 70° the flow is about 75 lbs. per hour. At 72° the flow is about 20 lbs. per hour. At 74° to 75° the valve entirely shuts off. It is evident that the tempera ture of the car equipped with this apparatus would rise to that temperature at which just snfficient steam passes the steam-valve and into the car as is necessary to maintain an even temperature. and at no time is it necessary that the steam-valve should actually shut off. It gives a throttling action upon the flow of steam. Taking into consideration the rapid rate at which this valve closes. it will he seen that. under conditions of railway service, the temper ature of the car would be kept practically constant. In actual practice it has been found that the temperature of the car will be kept at 70° and within a maximum variation of 2°.
The detailed construction of this apparatus can be seen from Fig. 4. Two metallic dia phragms are employed, which are brazed together at the edges, and have metallic hubs soldered to their opposite faces at their centers. (See section on line .4.) A small quantity of a liquid whose boiling-point is GO' F. is placed within the space between the two dia phragms. The opening to this space is then hermetically sealed. The diaphragm is then attached into a bronze framework in such a manner that the expansion of the diaphragms is communicated by means of it lever to a bell-erank, which through a rod actuates the steam valve below. This pipe is 5 ft. long and holds the two parts of this apparatus in rigid adjust ment, and also offers a protection to the rod. At a temperature below GO' F. the liquid placed between the two diaphragms remains in the form of a liquid, and the two diaphragms are collapsed. Above the boiling-point of the liquid in these diaphragms a vapor pressure is generated between the two diaphragms. forcing them apart and causing a motion in the vertical rod and its connecting inechanisin itgainst the tension of the spring shown in the framework of the regulator. The steam-valve is caused to close partially by this same movement.. When the temperature rises to 70' the valve almost reaches its seat, and simply allows sufficient steam to pass to preserve tin even temperature in the car. If a ventilator is open or in any way the air in the car is chilled. the effect on the diaphragms is to lower their temperature and to cause them to collapse, which is followed by a corresponding opening movement in the steam-valve. The results of tests with this apparatus have shown that the temperature of a car can be automatically held within a maximum variation of 2° with an external temperature varying front 50' above zero to 6° above zero in a run of 300 miles.