	
                           -- HELP SCREEN --



  This screen is presented for calculating required orifice area for
  GAS/VAPOR Sizing. After calculated area is determined, manually enter
  selected orifice area and API letter designation, for automatic calculat-
  ion of maximum flow capacity, reactive force at valve oulet, and noise
  level at a distance of three feet from discharge at outlet.


  Use the ENTER key to move through the input fields for changing any data
  for recalculations. Function key F1 will calculate orifice area.
  When calculation is completed, press F8 to store data for later retrieval
  or F2 for API spec sheet.

                          ͻ
                      ͹ UNIT CONVERSIONS 
                          ͼ
  ͻ
           TO CONVERT                  INTO          MULTIPLY BY      
  ͹
   Millimeters Water Column           in wc            0.0394         
           (mm wc)                     oz              0.0227         
                                       psi             0.001421       
  Ķ
   Millibars  (mb)                    in wc            0.4019         
                                       oz              0.2320         
  Ķ
   Kilograms/cm2  (kg/cm2)             oz            227.60           
                                       psi            14.22           
  Ķ
   Liters per Hour (l/h)             gpm (US)          0.0044         
   Cubic Meters/Hour (m3/h)          gpm (US)          4.403          
   Kilograms/Hour (kg/h)             gpm (US)        1/ 227.1 x G     
   Imperial Gallons/Minute           gpm (US)          1.201          
  Ķ
   kg/h                               scfm          13.93/ M          
   Nm3/h                              scfm             0.6216         
   Nm3/min                            scfm            37.30           
  ͼ

     NOTES: G = Specific Gravity of liquid
            M = Molecular Weight of gas


     If flow is expressed in actual volume, such as cfm or acfm, this
     flow can be converted to scfm as follows:

                            14.7 + p     520
           scfm = (acfm) x   x 
                              14.7     460 + t

           Where: p = gauge pressure in psig
                  t = temperature in deg. F
               acfm = actual cubic feet per minute

                       ͻ
                        REACTIVE FORCE CALCULATION 
                       ͼ

    The formula for determining reaction forces in an Open-Discharge
    system TO ATMOSPHERE through an elbow and vertical discharge pipe
    was revised in 1989 to include the additional forces generated at
    the valve outlet area. In order to determine total reactive forces,
    the following should be added to the calculated force to obtain
    the actual force: ( Ao x P2 ), based on schedule 40 tailpipe.

               VALVE OUTLET    AREA (Ao)          Ao x P2

                    2"        3.356 sq. in.      49.33 lbs.
                    3"        7.393 sq. in.     108.68 lbs.
                    4"       12.730 sq. in      187.13 lbs.
                    6"       28.890 sq. in.     424.68 lbs.
                    8"       50.027 sq. in.     735.40 lbs.
                   10"       78.854 sq. in.    1159.15 lbs.
                   12"      113.040 sq. in.    1661.69 lbs.

    EXAMPLE: If calculated reactive force is 832.40 lbs., and the
             size valve selected, determined by orifice calculation
             is 3" Inlet x 4" Outlet, add 832.40 + 187.13 for an
             actual reactive force of 1,019.53 lbs.


                ͻ
                   PILOT-OPERATED SAFETY RELIEF VALVES   
                                                         
                         ORIFICE AREA, SQ. IN.           
                ͼ
              
  VALVE SIZE    TYPE X33   TYPE X23   TYPE X73   TYPE 226/526   TYPE 727
 
 1x2, 1-1/2x2   0.156 (D)  0.326 (F)     --           --          --
                0.272 (E)    --          --           --          --
    1-1/2x2       --         --         1.336         --          --
              
    1-1/2x3     0.615 (G)  0.838 (H)     --        0.841 (H)      --
              
     2x3        0.647 (G)  1.371 (J)    2.530      1.375 (J)     0.503 (G)
                0.998 (H)                                        0.785 (H)
                                                                 1.287 (J)
              
     3x4        1.487 (J)  3.062 (L)    6.651      3.073 (L)     1.287 (J)
                2.218 (K)                                        1.838 (K)
                                                                 2.853 (L)
              
     4x6        3.603 (L)  6.824 (P)    9.629      6.848 (P)     2.853 (L)
                4.482 (M)                                        3.600 (M)
                5.185 (N)                                        4.340 (N)
                                                                 6.380 (P)
              
     6x8       12.671 (Q) 17.087 (R)              17.149 (R)    11.050 (Q)
                                                                16.000 (R)

   6x DUAL 8                          21.520

   8x DUAL 8                          29.420
              
    8x10                 27.813 (T)               27.913 (T)    26.000 (T)
              
   8x DUAL 10                         44.180

  X = SERIES 200/400/600/900 POSRV










                           CONVERSION CURVE
                   Altitude to Atmospheric Pressure

              Altitiude (thousands)       Atm. Pressure

                       1                     14.3
                       2                     13.7
                       3                     13.2
                       4                     12.7
                       5                     12.2
                       6                     11.8
                       7                     11.3
                       8                     10.9
                       9                     10.5
                      10                     10.1
                      11                      9.7
                      12                      9.3
                      13                      9.0
                      14                      8.8
                      15                      8.5
 


                             END OF HELP

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