This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
Every heating and every power plant should be provided with automatic means for closing the dampers when the steam pressure reaches a certain point, and for opening them again when the pressure drops. There are various regulators designed for this purpose, a simple form of which is shown in Fig. 65.
Steam at boiler pressure is admitted beneath a diaphragm which is balanced by a weighted lever. When the pressure rises to a certain point it raises the lever slightly and opens a valve which admits water under pressure above a diaphragm located near the smokepipe. This action forces down a lever connected by chains with the damper and closes it. When the steam pressure drops, the water valve is closed, and the different parts of the apparatus take their original positions. Another form similar in principle is shown in Fig. 66. In this case a piston is operated by the water pressure instead of a diaphragm. In both types the pressures at which the damper shall open and close are regulated by suitable adjustments of the weights upon the levers.
The method of making the pipe connections in any particular case will depend upon the general arrangement of the apparatus and the various conditions. Fig. 67 illustrates the general principles to be followed, and by suitable changes may be used as a guide in the design of new systems.
Steam first passes from the boilers into a large drum or header; from this a main, provided with a shut-off valve, is taken, as shown; one branch is carried to the engines while another is connected with the heating system through a reducing valve having a by-pass and cut-out valves. The exhaust from the engines connects with the large main over the boilers at a point just above the steam drum. The branch at the right is carried outboard through a back pressure valve which may be set to carry any desired pressure on the system. The other branch at the left passes through an oil separator into the heating system. The connections between the mains and radiators are made in the usual way and the main return is carried back to the return pump near the floor. A false water line or seal is obtained by elevating the pump regulator as already described. An equalizing or balance pipe connects the top of the regulator with the low pressure heating main and high pressure is supplied to the pump as shown.
A BATTERY OF IDEAL STEAM BOILERS SHOWING METHOD OF YOKING THE MAIN SUPPLY AND RETURN PIPE.
American Radiator Company.
A sight feed lubricator should be placed in this pipe above the automatic valve, and a valved by-pass should be placed around the regulator for running the pump in case of accident or repairs. The oil separator should be drained through a special oil trap to a catch basin or to the sewer, and the steam drum or any other low points or pockets in the high pressure piping dripped to the main return through suitable traps.
Means should be provided for draining all parts of the system to the sewer and all traps and special apparatus should be bypassed. The return pump should always be duplicated in a plant of any size as a safeguard against accident and the two pumps run alternately to make sure that one is always in working order. One piece of apparatus not shown in Fig. 67 is the feed water heater. If all of the exhaust steam can be utilized for heating purposes, this is not necessary as the cold water for feeding the boilers may be discharged into the return pipe and be pumped in with the condensation. In summer time, however, when the heating plant is not in use, a feedwater heater is necessary, as a large amount of heat which would otherwise be wasted may be saved in this way. The connections will depend somewhat upon the form of heater used, but in general a single connection with the heating main inside the back pressure valve is all that is necessary. The condensation from the heater should be trapped to the sewer.