GETTING THE MOST OUT OF INADEQUATE HYDRANTS
TRAINING NOTEBOOK
Inadequate fixed hydrants —those that flow less than 500 gpm—are a hindrance to fighting fires in rural areas. Along with manpower limitations, tightened budgets, and aging equipment, insufficient hydrants result in the inability to successfully deliver a continuous water supply via a water shuttle to a fire scene. The Holiday Shores Fire Protection District in Edwardsville, Illinois, developed a method to obtain maximum tanker filling capability when forced to use inadequate fixed hydrant water supplies.
REQUIRED EQUIPMENT
Necessary for the procedure arctwo personnel, a midship-mounted pumper, a minimum of two sections of large-diameter hard suction hose, a double female adapter for hard suction to the hydrant, one portable dump tank (any size), one low-level strainer, and one hydrant.
PROCEDURE
Setting up. You and a fellow firefighter respond in a midship-mounted pumper to a hydrant and begin setting up for a water shuttle by making the connections for hydrant-to-pumper suction intake (right side). Next, assemble and position the dump tank on the opposite side of the truck, in view of the pump operator. Attach the lowlevel strainer to a hard suction hose for the dump tank and install the hose to the pumper suction intake (driver’s side of pumper); position the strainer in the dump tank. Now, fully open the hydrant and water will flow through the midship pump and into the dump tank. At this time the pump is not yet primed or engaged.
As water is flowing into the dump tank, lay hoses from pump discharges for multiple tanker filling. Then prime the pump, which may be accomplished while flowing from the hydrant through the pump to the tank in midship-mounted pumpers. (Hydrants found in our area are the selfdraining barrel type. Any difficulty found in the initial priming of the pump may necessitate checking the hydrant to ensure that it is either fully open or fully closed, which eliminates a possible air leak in through the hydrant drain.) Engage the pump and leave the engine at idle rpm. Shut off the hydrant fully when the dump tank is full if the first empty tanker has not yet arrived. At this point, the pump is engaged, the booster and dump tanks are full, and the hydrant is off (or is open and still filling the dump tank).
Operations. As tankers arrive to be filled, the pump operator remains at the pump panel and the other firefighter makes and breaks the tanker fill connections. After a connection is made, the pump operator charges the Line to the appropriate pressure. Ensure that the tank vessel is properly vented to accommodate the additional pressure from filling w ith a pumper. (Our three tankers will handle 120 psi engine pressure initially, then reduce to about 80 psi for the last quarter fill with no damage to the tank. Use lower pressures with any mutual-aid tanker.) Begin filling the tanker and open the hydrant valve if it is closed.
As the tanker is being filled, the primary source of water is the hydrant because it is flowing under pressure, little as it might be. The secondary source automatically comes from the dump tank as the pumper demand exceeds the hydrant flow and a negative pressure is created, causing the water in the dump tank to be lifted into the pump at draft. When the tanker is full and the pumper discharge is closed, the supply from the hydrant will exceed the demand and the dump tank automatically will refill as long as the hydrant remains open.
At all times as the tanker is filling, the pump operator must monitor the water level in the dump tank so it does not become too low. If the tanker is not yet filled, the hydrant is open, and the dump tank is becoming low, open the booster tank-to-pump valve and at the same time operate the outlets restricting the water flow so that the hydrant recovers its ability to supply, the booster tank augments momentarily, and the level in the dump tank begins to increase. The gates can be used like a throttle to keep the level in the dump tank rising steadily. This will not let the booster tank completely drain, resulting in a loss of prime. Nowthe primary source of water is still the hydrant, and the secondary source is the booster tank.
As the tanker nears capacity, you will drop dow n outlet pressure using the gate valves. When the tanker is full, close the discharge valve and the tank-to-pump valve. With the pump still engaged at idle rpm, open the tank refill valve. The booster tank will refill as the dump tank is refilling. Essentially, the water from the hydrant fills the dump tank and the pump operator simply diverts water flow to either refill the tankers or to replenish (and consume) the booster tank when needed. The refilling and drafting of the water in the dump tank occur as a result of discharge demand vs. hydrant flow.
If a front-mounted pumper is used, the theory behind the operation remains the same, with a few variations. Connect the suction hose from the hydrant to the main front suction intake. Connect the suction hose with the low-level strainer to the gated inlet at the front suction intake and position the dump tank in view of the pump operator. When the hydrant is opened, water will flow through the inlet into the dump tank. With a frontmounted pumper, filling the dump tank requires more time, since the pump cannot be used to assist hydrant flow for this operation. When an empty tanker arrives, make the necessary connection. With the pump primed and engaged, open the discharge valve. Now, water from the hydrant and the dump tank will be suctioned into the pump and discharged into the tanker.
As before, monitor the water level in the dump tank and operate discharge and booster-tank valves as necessary to prevent emptying the dump tank and the resulting loss of prime. When the tanker is full, close the discharge valve and the booster tankto-pump valve and refill the booster and dump tanks.
BENEFITS
With minimal practice, this method will allow you to use water hydrants and even flush hydrants that previously were thought to be inadequate for tanker-refilling purposes. This method also eliminates the possibility of damage to underground mains due to excessive vacuum, and there is no possibility of water hammer damage due to the open-ended system. This procedure presents many advantages at no additional cost of manpower or equipment.
