Augmenting Fire Standpipe Systems

Importance of To provide independent and redundant primary or secondary water supply. Floor outlets eliminate the need to stretch hose lines from the pumper to the upper floors or deep inside a larger area building.

Principles To properly supply a standpipe system, the following principles are involved; Nozzle pressure and friction loss in the attack line, Head pressure due to elevation, Friction loss in the system, Friction loss in the supply line from the pumper to the FDC.

FD Operational Variations

Fire Department Variations: Attack and Supply lines; Some FD’s use a smooth bore or a combination (fog & straight stream) nozzle with 1 ½”, 1 ¾”, or 2” hose with lengths up to 150’, Some FD’s use 150’-200’ of 2 ½” hose with a smooth bore or a combination nozzle, Some FD’s use a short length of 3” hose off the outlet, then connect a gated wye,

Different strokes for different folks Some FD’s use 50’ of 2 ½” hose to a gated wye, supplying two 100’ lengths of 1 ½” – 2” hose with combination nozzles, One large metropolitan FD use 3 ½” hose with 3” couplings to supply the FDC, Some FD’s use LDH with Storz couplings to supply the FDC or as a temporary backup for the system,

Storz Connections

LDH used as replacement to system Reasons for use: 1.Damaged, inoperable or defective standpipe system. 2. Pressure Restricting Valves or Pressure Reducing Valves (PRV’s) that cannot be overridden. 3. Heavy volume of fire requiring greater fire flow.

Hypothetical Situation

Scenario Fire is on the eighth floor of a high rise. For the purpose of this presentation, we will assume the use of 200 ‘ of 2 ½” hose for the attack line, with a 1 1/8” smooth bore nozzle. Supply to the FDC is two individual 50’ lengths of 2 ½” hose.

Hydraulics

Attack Line using a Smooth Bore 1 1/8” nozzle with 50 psi nozzle pressure. Formula: GPM= 29.7*(D2)*Sqrt of the Nozzle Pressure. 29.7*1.265652*7.0710678= 265.8 (266 GPM)

Friction loss in attack line of 200’ of 2 ½” hose: Formula per 100’: FL= C*Q2 / 10000 2 * 2662 /10000 = 14.1512 * 2 = 28.3024 Friction Loss 200” 2 ½” hose= 28 psi

Elevation (head pressure): 5 psi per floor * 8 floors = Elevation = 40 psi.

Friction loss in the standpipe system: Friction loss in system = 25 psi. Note: With the various size of riser pipes, (4”, 5”, 6”) it is a generally accepted practice to use 25 psi friction loss in the system to make it easier to calculate desired engine pump pressure.

Friction loss in two individual 50’ lengths of 2 ½” hose supply line; Formula per 50’: FL = C*Q2 / 2 / 10000 2* 133/2/10000 = 1.7689 Friction Loss in Supply line = 2 psi

Calculations Nozzle Pressure (50 psi nozzle) 50 psi Friction loss in attack line 28 psi Elevation 40 psi Friction loss in standpipe system 25 psi Friction loss in supply line 2 psi Total 145 psi

Engine Pump Pressure = 145 psi

General Operations

To ensure adequate water: Supply the system from two pumpers, if possible, If the system has interconnected standpipe FDC, supply them both, If only one FDC present, supply 1st floor hose outlet with additional line, If building is equipped with a separate sprinkler and a standpipe system FDC, supply the standpipe first.

Supply the Standpipe 1st

If the standpipe is equipped with pressure-reducing hose valves, the valve acts as a check valve, prohibiting pumping into the system when the valve is open, A supplementary single-inlet FDC or hose valve with female threads at an accessible location on the standpipe allows pumping into that system.

Operations

Engine Co. Chauffer Test the hydrant before connecting, let Engine Officer and/or IC, know if the hydrant is not operational, thereby causing a delay in supply, Try to keep supply line to FDC not more than 100 feet, Remove kinks and sharp bends, Supply the FDC with the largest available hose, Increase pump pressure slowly to avoid pressure surges at the nozzle.

Use at least two supply lines to FDC if; more than one attack line being used from the standpipe or, indications from attack crew not enough water volume or pressure. Use the floor outlet(s) to supply the system if; leak in the piping at any point below grade allowing water to drain off, foreign matter pushed in the FDC, FDC inoperative.

FD Connection

FDC Safety consideration: Do not put your hands in the FDC to clear debris out, because it may have the presence of: broken glass, sharp metal, used drug needles.

Cans, bottles, balls, metals and drug needles have been shoved into FDC

Difficulties may be encountered with FD connections. These difficulties may include: missing caps, defective or incompatible threads, debris stuffed into the connection, tight caps, female swivels out-of-round, frozen female swivels, and clappers either broken or jammed open.

Many FDC’s are equipped with either metallic or plastic vandal proof caps, these caps are usually attached with screw eyes placed over the pin lugs on the female swivel, both metal and plastic caps are removed by striking the center of the cap with a tool, caps can also be removed by prying one of the screw eyes off the pin lug.

Some FD’s use security caps, responding via mutual aid, without the key, you will not be able to remove the cap…….. therefore, you will have to supply the system through floor outlets.

Knox registered FD ‘s should request extra keys for their mutual aid departments FDC Plug Key

Summary Test hydrant before committing, Use largest adaptable hose to supply system, Don’t put your hands into FDC, If FDC is inoperative, don’t waste time, supply system thru floor outlet(s), If supplying floor outlet(s), remember proper fittings, If your FD has security caps/plugs, make sure responding FD’s have keys provided to them.

Prepared by Thomas Bartsch Chief Fire Inspector (ret)