Section 322. Standard of pressure

The minimum pressure of gas so furnished
  or supplied which shall be permitted in any service  main  in  any  such
  city  shall  be sufficient to balance a column of water one and one-half
  inches in height. The maximum  pressure  therein  allowed  shall  be  an
  amount  sufficient  to balance a column of water three and three-fourths
  inches in height, plus  an  allowance  at  the  rate  of  one  inch  for
  variation  of  each  one  hundred  feet  of  increase in altitude in the
  distributing system between the holder and  the  point  of  consumption,
  except that no maximum pressure shall be prescribed in service mains the
  pressure  of  gas from which is regulated by service governors, supplied
  and maintained without charge to consumers.