US Laws, Codes, Statutes & Cases

 
    §  27-945 Water supply for standpipe systems. (a) Primary water supply
  for standpipe systems. Every standpipe system  except  nonautomatic  dry
  standpipe  systems  shall  have  a primary water supply available at all
  times at every hose outlet, or made  available  automatically  when  the
  hose  valve  at  any  outlet is opened. Such primary water supply may be
  from one or more gravity tanks from a pressure tank  or  tanks,  from  a
  direct  connection  to a city water main, from a connection to a private
  water main, or from an automatic fire pump.
    (b)  Method  of  providing  water  supply   for   standpipe   systems.
  Combinations  of  two or more of the following methods shall be used; in
  using such combinations, the siamese connections shall be considered  as
  a source of supply.
    (1) Direct connections of standpipes to the city water system provided
  one of the following conditions is met:
    a.  A  statement  furnished  by  the  bureau  of  water  supply of the
  department of environmental  protection  indicates  a  pressure  in  the
  street main that is capable of maintaining a static pressure of at least
  fifteen  psig.  at the highest hose outlet between the hours of eight a.
  m. and five p. m.  on a normal working day  when  a  street  level  fire
  hydrant  within  two hundred fifty feet of the building is supplied from
  the same street main and  is  discharging  at  least  five  hundred  gpm
  through a two and one-half inch hydrant butt.
    b. For buildings forty feet or less in height with an area of not more
  than  twenty thousand square feet per floor, there is a four inch direct
  connection to the street main that is fed two ways or there  is  a  four
  inch  direct connection to each of two street mains on two street fronts
  so installed that shutting off one service will not interfere  with  the
  supply of the other, and there is sufficient pressure in the street main
  to  maintain  a  minimum  static  pressure  of  twenty-five psig. at the
  highest  required  hose  outlet  and  the  department  of  environmental
  protection states that the required street pressure is available.
    (2)  A private yard main when meeting the conditions of a direct water
  connection to the city water system.
    (3) Gravity tanks provided:
    a. The minimum quantity of water reserved  for  standpipe  service  is
  thirty-five hundred gallons in each standpipe zone.
    b. The bottom of the tank shall be at least twenty-five feet above the
  highest  hose outlet that such tank supplies, (except the roof manifold)
  and those hose outlets in a penthouse  enclosing  mechanical  equipment,
  except as otherwise provided in subparagraph e of this paragraph.
    c. Each zone of the standpipe system having three risers or more shall
  have a total fire reserve capacity of five thousand gallons or more from
  one or more gravity tanks for each zone.
    d.  Where a group of two or more buildings, connected or separated, is
  operated under a single control, a single gravity  tank  having  a  fire
  reserve  capacity  of  at least five thousand gallons may be accepted as
  the primary water supply for  the  several  standpipe  systems  of  such
  group,  provided  a dead riser is carried from the bottom of the tank to
  an underground header or  cross  connection  system  and  provided  each
  building unit has a post indicator type control valve outside or an o.s.
  and  y.  control  valve  inside  the  building  at  a readily accessible
  location. The underground cross connection  may  not  cross  any  public
  street without the approval of the city departments having jurisdiction.
    e.  Useable  storage  or  office  space  on  penthouse floors shall be
  provided with a riser  outlet  valve  within  the  distances  stated  in
  section  27-935  of this article. In lieu of elevating the bottom of the
  gravity tank twenty-five feet above these  outlets,  an  automatic  fire
  pump  with  local supervisory alarms may be installed. The pump shall be

  capable  of  delivering  two  hundred  fifty  gpm.  at  a  pressure   of
  twenty-five  psig.    above  the  normal  static pressure at the highest
  outlet supplied by the pump.  The  pump  shall  take  suction  from  the
  gravity  tank and be so arranged as to permit the siamese connection and
  any required manual fire pump to supply  these  outlets.  No  more  than
  three  stories  of  any  penthouse  or of penthouse and building stories
  combined, may be supplied by this method.
    (4) Pressure tanks shall be acceptable as the primary  supply  to  the
  system provided all of the following conditions are met:
    a.  A  pressure  tank,  or  tanks,  so proportioned and located that a
  pressure of at least fifteen psig will be available at the nozzle of the
  highest required hose station, exclusive of roof outlets, when  all  the
  water has been discharged from the pressure tank.
    b. The storage quantities stated for gravity tanks in subparagraphs a,
  c and d of paragraph three of this subdivision are met and an additional
  volume  equivalent  to  one-half  of the required water storage space is
  provided for the required air.
    c. An air compressor is provided with suitable automatic  control  and
  of sufficient capacity to build up air pressure of at least seventy-five
  psig.  in  the tank within three hours and to maintain thereafter an air
  pressure between seventy and eighty psig. The  automatic  control  shall
  also maintain the proper air-to-water ratio in the pressure tank.
    d.  Pressure  tanks shall be supplied with water through a fixed pipe,
  independent of the standpipe riser, and at least two inches in size. The
  water supply and connection shall be capable of supplying the tank at  a
  rate  of  at  least  sixty-five gpm without reducing the pressure in the
  tank. The tank shall have a fixed water level plate on the end  opposite
  the gauge glass, or other equivalent indicating device.
    (5)  An  automatic fire pump shall be acceptable as the primary supply
  to the system provided:
    a. The building is three hundred feet high or less, or if the building
  is higher than three hundred feet, the automatic fire pump is used  only
  for  the  lower  three  hundred feet. The zones above three hundred feet
  shall be supplied by either a gravity tank conforming to paragraph three
  of subdivision (b) of this section or  a  pressure  tank  conforming  to
  paragraph  four of subdivision (b) of this section and in addition shall
  be supplied by the manual fire pump required by section 27-946  of  this
  article.
    b.  The  automatic  fire  pump  supplying  the system or section has a
  capacity of at least five hundred gpm with a discharge  pressure  of  at
  least  twenty-five  but  not  exceeding  seventy psig (above the normal)
  static pressure at the highest hose outlet within the zone  supplied  by
  the pump plus the frictional resistance from the pump to the outlet at a
  flow of five hundred gpm.
    c. The electrical power to the pump is connected to the street side of
  the building service switch.
    (c)  High  and  low risers and cross connections in standpipe systems.
  When tanks are used for the primary water supply, the standpipe  systems
  may use separate riser systems serving, respectively, low and high parts
  of  the  building.  Separate  gravity tanks or pressure tanks may supply
  each zone, but in every case the standpipe system shall be  so  designed
  that  every hose outlet of the entire system can be supplied through the
  required cross connections from every siamese connection and from  every
  manually operated fire pump located at or below the street level.
    (d)  Use  of  standpipe  riser  for  sprinkler  system  water  supply.
  Standpipe risers may be used to supply water to sprinklers in  buildings
  classified in occupancy group E, one hundred feet or more in height, and
  in  existing  office  buildings,  one hundred feet or more in height, in

  accordance with applicable provisions of this subchapter  and  reference
  standards RS17-1 and RS17-2.