Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems
By Hansford Stewart
It’s the first day on the job as a new inspector and you show up at the installation for the inspection and annual test. All of the records, including the certified factory test curve, instruction manuals, and annual test results, have disappeared faster than Mona Lisa’s smile in a Daniel Brown novel. You look over the installation and are amazed
that this equipment can even operate, let alone provide water under pressure, during a demand situation.
NFPA 20 requires that the fire pump equipment be protected from possible interruption of service through damage caused by explosion, fire, flood, earthquake, rodents, insects, windstorm, freezing, vandalism…obviously, we should have included walls falling on the equipment. It is interesting to note that the only item left standing was the fire pump.
Wall collapsed on Fire Pump Equipment
Automatic fire pump systems are very reliable and have been a key factor in reducing property damage and the death rate in commercial and residential applications. When they fail, it is usually because they have not been maintained, inspected, or tested in accordance with NFPA 25. NFPA 25, Chapter 8 provides minimum requirements for inspection, testing, and maintenance of fire pump assemblies. Let’s take a look at some of the key items covered by this standard.
Obviously, the purpose of the inspection is to verify that the pump assembly is in good working order and is free from physical damage. It is important to notify the supervi- sory service before conducting any test or procedure that could result in a false alarm.
This is not an inclusive list of items to be inspected, but includes many important considerations:
Coupling alignment is a critical item and should be checked annually. Many factors can affect alignment, such as thermal expansion and maintenance on the equipment. If the equipment is out of alignment, it could cause premature failure and possible disruption of service.
Circulation Relief Valves:
NFPA 20 5.11 requires that electric driven fire pumps be supplied with an automatic circulation relief valve. This valve is typically mounted on the neck of the discharge flange, before the discharge check valve. Circulation relief valves prevent the pump from overheating when operating at shutoff condition (no flow). The relief valve should be 3/4″ for flows not exceeding 2500 GPM and 1″ for pump with a rated capacity of 3000 to 5000 GPM. This valve should be inspected during your weekly test and should discharge to drain. Visual verification of the valve’s operation is critical; if the valve fails to operate, your fire pump will overheat in a very short period of time, as illustrated below.
NFPA 20, 2003 Edition section 22.214.171.124 requires that the circulation relief valve be listed for fire pump service.
NFPA 20 section 126.96.36.199 requires that on applications where the suction supply is of sufficient pressure to be of material value to the system without the pump, the system shall include a bypass. This would allow you to do mainte- nance on the pump and still have some pressure available for your system. This will not give you 100 PSI at the furthest hose connection, but would afford some level of protection for the property.
The pump suction, discharge, and bypass valves should be checked weekly to verify that they are fully open.
A weekly test should be conducted at no flow (shut off) condition. If the fire pump is an electric unit, test for 10 minutes. A diesel unit must be tested for 30 minutes every seven days. The Automatic Weekly test timer can be used for the test, but qualified personnel must be in attendance.
The annual test must be conducted at minimum, rated, and peak load. You must place a demand on the suction supply every third year; this requires a test via hose streams or via a flow meter loop to drain or to the reservoir. You can use a flowmeter loop piped to the pump suction (closed-loop metering) in the off years. The annual test data should be compared to the acceptance test and the certified factory test curve.
Sample certified factory performance test curve
Degradation in excess of 5% of the pressure to the initial unadjusted acceptance test curve shall require an investiga- tion to reveal the cause of degraded performance.
Pressure gauge accuracy should be checked annually
(change or recalibrate when 5% out of calibration).
A preventive maintenance program shall be implemented on all components and records shall be maintained on all work performed. Typically, the manufacturer’s recommen- dations should be followed, but NFPA 25 table 8.5.3 can be used as substitute requirements.
The importance of proper bearing lubrication cannot be overstated. It is difficult to judge how often a bearing should be greased. Many factors will influence the schedule, including the conditions of operation. A good “rule of thumb” is to add an ounce of grease every 3-6 months. NFPA 25 table 8.5.3 recommends an annual lubrication of the bearings. Make sure to avoid adding too much grease.
A preventative maintenance program must be established on the components of the pump assembly. The manufacturer’s recommendations must be followed. NFPA 25 requires that records shall be maintained on all work performed on the pump, driver, controller, and auxiliary equipment.
Stationary pumps dedicated for fire protection service save lives and protect property. They have proven to be very reliable, provided that they are inspected, maintained, and tested in accordance with the requirements of NFPA 25.
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