When changing from a tank to pump operation to a pressurized (hydrant) operation, the bleeder valve on the hydrant supply line gate should be opened to:

When changing from a tank to pump operation to a pressurized (hydrant) operation, the bleeder valve on the hydrant supply line gate should be opened to:

• A. Test hydrant flow
• B. Close the hydrant valve
• C. Increase pressure to hydrant
• D. Remove air from the line prior to opening the gate

Answer: (D)

Purging air from the hydrant supply line is essential when switching from tank to hydrant operation. The line can contain trapped air that, if not vented, prevents a solid water column and can cause water hammer or cavitation when the hydrant gate is opened. Opening the bleeder valve allows the air to escape and the line to fill with water, producing a stable, continuous flow once the hydrant gate is opened. After the bleed is complete and water is seen, close the bleeder and gradually open the hydrant gate to the desired flow. This ensures a smooth transition and protects the pump and hoses from shock and damage.

Purging air from the hydrant supply line is essential when switching from tank to hydrant operation. The line can contain trapped air that, if not vented, prevents a solid water column and can cause water hammer or cavitation when the hydrant gate is opened. Opening the bleeder valve allows the air to escape and the line to fill with water, producing a stable, continuous flow once the hydrant gate is opened. After the bleed is complete and water is seen, close the bleeder and gradually open the hydrant gate to the desired flow. This ensures a smooth transition and protects the pump and hoses from shock and damage.