Document QgGeGo92paRG1NeJmOyzqDBJ6

American Society of Heating and Ventilating Engineers Guide, 1930 the heater or boiler. A float-controlled valve is placed on the air outlet of the separating tank and so arranged that when the water of conden sation has insufficient head to flow by gravity to the point of use, the air will be confined in the upper part of the tank. Its operation is such that when the pump continues to deliver water and air to the tank the pres sure within the tank increases until it becomes sufficient to discharge the water, thus lowering the water line and eventually permitting escape of Fig. 3. Method of Connecting Vacuum Pump, Feed Water Heater and Single Control Hydro-Pneumatic Tank or Air Separating Tank the surplus air through the float-controlled air valve. The confined air pressure in the tank plus the gravity head in the tank discharge pipe, must be sufficient to cause flow to the place of disposition. This confined air pressure, plus the column of mixed air and water in- the pump discharge to the tank, constitute the total head against which the pump must act. Fig. 3 shows a hydro-pneumatic separating tank, as well as a freelyvented separating tank, for alternate use as conditions require. Where the pressure in the heater, boiler, etc., varies materially from time to time and where it is desired to save energy by diminishing the head against which the pump shall work, a hydro-pneumatic type tank may be used, instead of a plain tank set at a higher elevation, to over come-the peak pressure in the boiler or heater. - Table 13 gives the size of plain and hydro-pneumatic tanks for air separating purposes and also those for storage of returns. In the latter case the tanks are based upon storing the quantities of water which will be discharged during five minutes at the basis of hourly rates given in the first column. When the' head on the delivery side of steam-driven vacuum return pumps exceeds 15 lb. per square inch the condensate should be delivered 320 Chapter 19--Pumps and Traps Table 13, Sizes of Plain and Hydro-Pneumatic Separating Tanks Condensation Pounds per Hour 4.000 6.000 8,000 10,000 16,000 24,000 34,000 45,000 60,000 For Air Separation Only Diameter Inches Length Inches 12 24 12 36 18 30 18 48 24 48 30 48 24 72 36 60 36 72 42 60 36 96 42 72 42 96 AmFob Separation and Water Storage Diameter Inches Length Inches 24 36 24 48 24 72 30 48 30 60 36 60 36 72 36 96 42 72 42 96 48 72 48 96 to a vented receiver located close to the level of the vacuum pump outlet. This receiver should be connected to a separate steam or power driven water pump capable of delivering against the maximum head and should be controlled by a throttle valve or motor control, actuated by some suit able means, from the water line in the receiving tank. Typical vacuum pump connections for several different conditions of service, are shown by Figs. 4, 5 and 6. LIFTS In vacuum heating systems where condensation is to be raised to a higher level it should be accomplished by means of lift fittings. Lifts of 6 ft. or over should be made in steps rather than in one rise or through drag lift (consisting of long upwardly-inclined pipes.) In any case the pipes between the lifts should grade downward toward the pump. SPECIFICATIONS FOR PUMPS General.--Reciprocating and power driven pumps should be specified as to make, size, working water and steam pressures, piston speed, tem perature of water to be handled, electric motor characteristics, and to insure economy in production, such standard practices as subsequently indicated. The kind of drive should be specified for power-driven pumps. Centrifugal and rotary pumps should be specified as to make, type, capacity, temperature of water to be handled, speed and motor char acteristics, including the following: " (1) Name of motor manufacturer; (2) manufacturers rated horsepower; (3) the maximum temperature rise (deg, cent.)-for any part of the motor above the temperature of the surrounding air; (4) full-speed in revolutions per minute; (5) current characteristics; (6) whether the motor is to be 321