Fire Pumps

Fire pumps deliver water with adequate volume and pressure to sprinkler and standpipe systems. A sprinkler system needs to be supported by a fire pump if:

• There is not enough volume or pressure in the public water supply.

• Changes to the operations of the building protected by the sprinkler system increase the fire risk, which requires a higher delivered density to the sprinkler heads.

• The volume or pressure of the public water supply has been negatively impacted by the demands of development and expansion.

There are two types of pumping systems based on the source of the water supply:

• A fire pump draws water from a private supply such as water impoundments, rivers, or underground aquifers. There is often only one fire pump in these types of systems and a limited supply of water.
• A booster pump attaches to a public water supply that has adequate capacity but inadequate pressure, when the public supply is not adequate to meet the demands of the sprinkler system due to fire loading, or in high- rise buildings where water must be delivered to upper floors. The system boosterpumpincreasestheavailable pressure to an adequate level.

Fire pumps are a critical component in the fire suppression system and, as with any other mechanical system, must be tested and maintained to maximize their reliability. These systems are dedicated to fire suppression and cannot function as a supply of domestic or process water. In a fire, pumping systems are designed to operate until they no longer function, whether they run out of fuel, experience power failure, or run to complete failure. 

• Pump: The type of pump used depends on the source of the supply. The pumps are sized according to the needs of the fire suppression system.

• HorizontalCentrifugal: Thisisthe most common type of pump, used in systems where there is some available pressure. Less common is the use of these pumps for suctioning water from a man-made or natural impoundment. This pump is connected in line with the prime mover.

• Vertical Lift Turbine: This pump is lowered into a water supply, which can include underground storage, wells, ponds, and rivers. The turbines have different stages to lift the water depending on its depth and elevation. This type of pump can be connected either in line or at a right angle to the prime mover.

Prime Mover: Numerous factors, including the location of the pump and the reliability of the power supply, are considered in the type of prime mover to be used in a pumping system. The most common types of prime movers are:

• Electric: Electric motors are one of
  the more popular and reliable drive systems. The integrity of the electrical system should be high and often backed up with a secondary supply. A fire proof power supply should be used.

• Internal Combustion / Diesel: When electrical supplies are remote or unreliable, internal combustion engines are the preferred method of driving the pump. A high degree of care is needed to maintain reliability, specifically with regard to the fuel supply.

Controller: This unit controls the starting and stopping of the prime mover and signals alarms. The type of controller is dependent on the type of prime mover.

The controller should start automatically when a pressure drop occurs in the fire system. Controllers should be arranged so the pumping system requires human response to shut down, rather than shutting down automatically.

Alarms: The National Fire Protection Association recommends the following alarms for fire pumps and their related equipment:

• Fire Pump Running
• Fire Pump Power Failure for electric motor
• Fire Pump Failure to Start for diesel engines
• Pump Controller not in Automatic Mode
• Diesel Engine Trouble to signal battery trouble, over speed, or low oil
• Pump House Temperature
• Suction Tank Low Water Level 

Regardless of the type of pumping system, maintenance and testing are necessary to ensure reliability. There are three variable factors to test — the pump speed, pressure, and discharge rate. Pump testing can be a dangerous operation, and all safety precautions should be taken.

Water supply: There must be an adequate and reliable water supply. This needs to be verified and tested on a regular basis. Typically, a weekly visual check of water levels or pressure is sufficient.

Exercise the pump: Pumps need to be started on a weekly basis by pressure drop to simulate actual starting conditions. The pump operates in churn, meaning the only water flowing will be from casing relief valves. The main difference between diesel and electric system churn tests is the time of operation. Electric systems need to run for only 10 minutes, while diesel-driven systems should operate for 30 minutes. This is the most overlooked part of the maintenance routine.

During this weekly operation, the following recordings should be taken:

• Record the system suction and discharge pressure gauge readings

• Check the pump packing glands for slight discharge

• Adjust gland nuts if necessary

• Check packing boxes, bearings, or pump casing for overheating

• Record the pump starting pressure

  Electrical system procedure:

• Observe the time it takes for the motor to accelerate to full speed

• Record the time the controller is on the first step (for reduced voltage or reduced current starting)

• Record the time the pump runs after starting (for automatic stop controllers)

Diesel engine system procedure:

• Observe the time for engine to crank

• Observe the time for engine to reach running speed

• Observe the engine oil pressure gauge, speed indicator, water, and oil temperature indicators periodically while engine is running

• Record any abnormalities

• Check the heat exchanger for cooling water flow

Steam system procedure:

• Record the steam pressure gauge reading

• Observe the time for turbine to reach running speed

Annual Flow Testing: Test pump flow annually by either connecting hoses to the pump header or by using a bypass flowmeter. The flowmeter results should be compared to verify that calibration of the meter is correct. Follow these steps during the annual flow test.

At no-flow condition (churn):

• Check the circulation relief valve for operation to discharge water
• Check the pressure relief valve (if installed) for proper operation
• Continue the test for 30 minutes

At each flow condition:

• Record the electric motor voltage and current (all lines)
• Record the pump speed in rpm 
• Record the simultaneous (approximately) readings of pump suction and discharge pressures and pump discharge flow

Proper maintenance and testing of fire and booster pumps will ensure these vital components work as designed when needed. These are highly engineered systems, which are also very reliable. The maintenance programs should be incorporated into your facility’s preventative maintenance program. 

NFPA 20   Standard for the Installation of Stationary Pumps for Fire Protection

NFPA 25   Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems