Document MMgMQbQN14by2q1va15m8VwqM

American Society of Heating ana Ventilating Engineers Guide, 1924-25 To use Table 58, multiply the quantity of condensate to be handled by the factor corresponding to the temperature of the con densate at the pump suction and select a pump suitable for the quantity thus found. The above increase in pump capacity may be. reduced by providing a static head above the pump suction and when this static head is made equivalent to 15 lb. the' absolute boiling pressure of the condensate (measured in feet of water) qo increase is necessary. Allow sufficient head in addition to the total head necessary to over come static head, velocity head,' pipe friction and boiler pressure, whereever condensate is to be returned direct to a boiler from the pump. TABLE 63. DUPLEX PISTON TYPE RETURN PUMPS WITH RECEIVERS STANDARD PRESSURE Sizb op Pump 3X2X3M 4MX2MX4 5K X3MX5 6X4X6 7Ji X 5 X 6 Receiver Capacity Gallons 12 20 40 60 100 Sq. Ft. Direct Radiation 6000 10,500 19,500 30,000 45,000 Lb. Condensate per Hour 2000 3500 6500 11,000 15,000 Minimum Steam Pressure 50 40 35 35 30 Low Pressure 4M X 2 X 4 12 6000 5K X2HX5 20 10,000 6X2MX6 40 120,000 6X3X6 40 180,000 6X3M X 6 60 290,000 2000 3500 4000 6000 9000 25 20 15 20 25 Return line vacuum heating pumps may be divided into three classes as follows: 1. Direct acting reciprocating steam driven vacuum return line pumps. 2. Reciprocating power driven return line vacuum pumps.. 3.' Motor driven return line vacuum pumps. In estimating the size of the vacuum pump, it is not sufficient to know merely the square feet of equivalent direct radiation. There are other variables which enter into the problem such as the following: 1. The degree of tightness of the system. 2. The efficiency of the radiator traps. 3. The temperature of the condensate at the pump. 4. The probable cooling effect of the return piping. 5. Are lift points required: in the return? 6. What vacuum must be. maintained at the pump? 7. Do large volumes of high temperature water enter the return piping near the pump? 8. Are the runs of piping long from the source of steam supply to the farthest radiator? High pressure traps should never discharge directly into a vacuum return. An excessive amount of vapor will form due to re-evaporation 80 :American Society of Heating and Ventilating Engineers Guide, 1924-25 of a considerable part of the hot condensation. This may cause a very material reduction in the vacuum maintained by the pump. Fig. 17 shows a method of disposing of the greater part of the vapor of re evaporation and at the same time lowering the temperature of the condensate. Fig. 17. Method of Discharging High-Pressure Apparatus into Low-Pressure Heating Mains and Vacuum Return Mains through a Low-Pressure Trap L'Discharge from VacuumPump (jiobe tbfve t'Li/brrcahr BalerFeedPump andReceiver S7pti/ef/cf/iaFFiliL'H'hmnqaQzdr'ibfve '* . , c Drum io Sewer Floor Line Fig. 18. Method of Connecting Vacuum Pump and Automatic Boiler-Feed DISPOSAL OF VACUUM PUMP DISCHARGE The discharge from reciprocating vacuum pumps of either the steam or power driven type is a mixture of water and air so that some means must be provided for releasing the entrained air. This requires water surface area in either a tank having a large horizontal cross section or a stand pipe of enough sectional area to permit a low velocity water flow downward while the entrained air is escaping to the surface against the 81