An increasing need for larger volumes of water during industrial emergencies exists today.
As Dave White described in his November /December 2003 editorial, an increasing need for larger volumes of water during industrial emergencies exists today. Even outside of the chemical/petrochemical industry, there are needs for larger amounts of water than in years past. For example, an Early Suppression Fast Response (ESFR) system in a commercial warehouse could need 2,000 gpm at more than 100 psi in order to properly operate. However, believe it or not, the water supply -- the very heart of the fire protection system -- is the most neglected part.
Regardless of your occupancy, if you need a large amount of water you'll typically need to employ a fire pump taking suction from a pond, tank, or city water main. In most industrial settings, diesel engine-driven fire pumps are used with electric motor-driven pumps as back up. Many commercial facilities use an electric pump only, often without a diesel generator as a backup power supply. Even if a back up to their power supply exists, the transfer switch is frequently overlooked during annual testing as described in NFPA 25 Inspection, Testing and Maintenance of Water-Based Fire Protection Systems.
You can have in-rack sprinklers in your warehouse, monster monitors for your process unit, or the most powerful foam pumper on the market and feel safe. However, all of the fire protection equipment in the world is useless if your water supply fails you when it's needed the most.
Pumped water supply systems can fail for many reasons. Just as human beings are typically the reason behind the causes of large property losses, they are often the reason that pumping supplies fail as well. Fire pumps can fail to operate properly or fail to run for the expected duration of the fire. These failures can include any of the mechanical or electrical systems and sub systems of the pump, driver, controller, or pump house. It is impossible to cover every type of failure in a single article. For a comprehensive troubleshooting guide, refer to Annex B of NFPA 20, Standard for the Installation of Stationary Pumps for Fire Protection.
We've focused on some of the areas that GE GAP Services find all-to-routinely during property loss prevention surveys or in training seminars.
Electric motor driven pumps can fail due to lack of a properly arranged power supply. Most often the power supply was not installed per NFPA 20. Diesel engine failures are typically due to lack of maintenance, testing, or understanding the fundamentals of how diesel engine driven fire pumps operate. Either way, this can lead to a lack of water for automatic and manual fire fighting efforts during critical times. This can endanger the emergency responder, the facility, the company, and the community.
A few of the major but not commonly understood reasons why diesel fire pumps fail include:
- fuel supply problems
- lack of cooling, and
- improper starting.
Fuel supplies are typically the most over looked part of the installation and subsequent maintenance. The tank is typically sized to meet only the minimum requirements of NFPA 20. If the tank isn't refilled regularly, there might not be enough fuel for a prolonged incident.
Due to cost considerations, the least expensive diesel fuel is often purchased which can lead to engine failure due to contaminated/coagulated fuel. Lower grade fuels are intended to be consumed quickly, not to sit in a stationary tank for prolonged periods of time. In most cases, weekly pump testing will include a check of the amount of diesel fuel in the supply tank but seldom does anyone check the fuel for contaminants or quality as required by NFPA 25.
A lack of proper cooling water for the diesel engine can be caused by many things, including clogged screens on the cooling line, an improperly adjusted regulator, or a failure of a cooling water solenoid. The best way to prevent these problems is proper inspection, testing, and maintenance. If prevention fails, and the engine overheats during an incident, properly trained personnel need to take action to provide supplemental engine cooling.
If people are relying on a specific individual to provide them with the proper amount of water during an incident that person will need to know more than the basics. Each fire pump needs to be monitored during an incident by a person trained in the nuts and bolts of fire pump operations. While not the most glamorous job during a fire, it is among the most important. Why? In the case of a cooling system problem, the pump will eventually fail once the engine overheats. There must be someone to detect this condition and correct it before the pump fails. Improperly trained personnel can severely damage the heat exchanger when using the bypass cooling line, as most installations do not have a pressure regulator as required in the later editions of NFPA 20.
The same holds true if a pump is manually started should it fail to start automatically. Failure to follow the manufacturer's instructions could lead to pump damage or in not being able to start the pump at all. If this occurs during an incident, the results can be devastating.
There is some good reading in NFPA 25, and in NFPA 20 concerning fire pumps. It is common to find pumps that have been installed incorrectly. This can lead to pre-mature pump failure. Examples are legendary.
You never know when your pump(s) will be called upon to defend you and your property from the threat of fire. Be on the safe side -- pay attention to your pumped water supplies.
1 When the Fire Starts, It's Too Late to Clean the Fuel, Sprinkler Age, July 2003 article by Terry Simmons Layton, Fuel Technologies.