Document Lpo3OOLVKjqBpZzRMexyaOoDX

American Society of Heating and Ventilating Engineers Guide, 1924-25 pump is maintaining a vacuum of 8 in. of mercury and handling air through a standard orifice corresponding to the air capacity of the pump as previously mentioned. TABLE 68. TWO PUMP ONE MOTOR RETURN LINE SYSTEM VACUUM PUMPS Capacitv Sq. Ft. op Direct Radiation 6000 6000 8000 8000 12,000 12,000 18,000 18,000 30,000 30,000 Capacity G. P. M. 9 9 12 12 18 18 27 27 45 45 Pressure at Pump 10 15 10 15 10 15 10 15 10 15 Motor H. P. k i i m i iy 2 2 3 F ig . 21. V olum e of A ir through Orifices under V acuum TABLE 69. TWO PUMP TWO MOTOR RETURN LINE SYSTEM VACUUM PUMPS S .Capacity q Ft. of Direct Radiation G.Capacity P. M. Pressure at Pump Motor H- P. Air Water 6000 9 10 yk 6000 9 15 yk 8000 12 10 yk 8000 12 15 yi 12,000 18 10 kk 12,000 18 15 ki 18,000 27 10 ki 18,000 27 15 k. 2 25,000 38 10 1 iy 25,000 38 15 i 2 30,000 45 10 1 iy 30,000 45 15 i 2 The capacities given in Table 70 are for pumps having water cylinder with the length of stroke equal to the diameter of the water piston. The capacities for pumps of a greater or less length of stroke may be found by use of the last two columns in this table as follows: Divide the stroke by the piston diameter and find the corresponding . ratio in the column headed stroke bore. The capacity factor opposite this in the last column is then multiplied by the capacity given in the table to give the capacity of the pump in question. PROPORTIONING OF STEAM END OF RECIPROCATING VACUUM PUMPS In proportioning the steam cylinder of the pump the following formula will give results which are safe to use. As X ^ = Aw X + Pa) 86 87