Supplying Pressurized Dry Hydrant Systems
© 2001 Capt. Willis Lamm, Water Supply Officer, Moraga-Orinda (CA) Fire District

The following procedures are examples of low water pressure evolutions based on the procedures of the Moraga-Orinda Fire District, presented for illustrative purposes.
  OBJECTIVE

Within 3 minutes, establish and support a 1000 GPM fire flow to an engine operating on the "dry" street while maintaining at least 10 p.s.i. residual on the supply hydrant and 20 p.s.i. residual on the discharge hydrant.

  OPERATIONAL PROCEDURES

The following procedures specifically apply to the Knickerbocker Ln. system and generally apply to all dry systems.

First Arriving Engine

  • Respond to the scene and attack fire from tank.

    Note: If the first engine is spotted close to the dry hydrant, it should make a direct connection via front or side suction.

First arriving engine laying
from "dry" hydrant

Second Arriving Engine

  • Lay supply line from the dry hydrant to the first arriving engine (if line not already established.)

    Notes: If supply line is already established, proceed directly to provide a 2-in 2-out rapid intervention team.

    Unless the first arriving engine is spotted at the hydrant, someone will need to stand by the hydrant to bleed air and open the discharge to the supply line.


Third Arriving Engine

  • Spot to make a front suction connection to the hydrant at the Knickerbocker Ln. cul de sac.

    • Be careful with apparatus placement and take a few spiral twists in the suction hose to prevent kinks.

    • Spotting the engine facing downhill will put the FDC within reach of a 100 ft. length of hose.
Supply engine making hookup

  • Pull 100 ft. of large diameter hose (LDH) from the engine to the FDC.

    • Place a 4½" x 2½" reducer on the hose prior to connecting to the FDC. (This sequence allows the FDC swivel to work.)

    • Connect the FDC hose to the LDH discharge on the engine.
Hooking up to the FDC

Supply Engineer

  • Establish and maintain 150 p.s.i. discharge pressure unless otherwise directed by the engine at the scene.

  • Adjust discharge pressure as necessary to compensate for elevation.

  • Before intake pressure falls critically low, establish a second suction line from the hydrant to the engine.

    (A residual pressure of 10 p.s.i. is not unlikely if you are flowing 1000 GPM.)


Running pressure to 150 p.s.i.

Hydrant Person

  • Bleed off all air using the 2½" discharge outlet.

  • When the engine at the scene is ready, completely open the LDH hydrant outlet.


7-26-00 TEST RESULTS

Knickerbocker supply hydrant:

    Static Pressure:

    Residual Pressure: (@ 1000 GPM)

    35 p.s.i.

    10 p.s.i.

Dry (discharge) hydrant:

    Static Pressure:

    Residual Pressure: (@ 1000 GPM)

    112 p.s.i.

    18 p.s.i.

Note:

We did not test this evolution using 2½" hose.

A dual lay would be required to deliver 1000 GPM. Based on rule-of-thumb, the discharge pressure from the supply engine would have to be increased by 40 p.s.i. for every 100 ft. of double lay used. (This would calculate to a minimum of 40 p.s.i. additional pressure required for the hose lay between the engine and the FDC.)


Additional evolutions will be presented
in this same format

Bleeding off air
before charging hose
Supply established to first engine
Flowing 1000 GPM.


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