As Andy Fredericks said, “Standpipes are like a large black hole.” Put water into one end, and you hope the water will flow to the other. This is God’s truth about fire protection systems. For most firefighters, the standpipe is one of the most confusing aspects of firefighting. If you don’t live in major cities that regularly fight fires in standpipe or high-rise buildings, you probably have little knowledge about these systems. Complex systems can be dangerous.
Understanding standpipes starts with technical data. This includes the classifications of standpipes and their types, as well as the relevant NFPA standards, recommendations, and other information. This information is the foundation. This standard and all the information it contains drive every decision in the selection and purchase of hoses, nozzles, and other equipment. These standards not only guide you in the design of your equipment but also how to pump it. There are three types of standpipes. For trained firefighters, Class I standpipes can be used.
Each riser has a 2 1/2-inch outlet. They can flow a minimum of 250 gallons per hour (GPM), from every outlet. Each riser must be capable of delivering 500 gpm. Each riser should have a pump that can deliver 500 gpm to the first one and 250 gpm each subsequent. This should last at most 30 minutes. For civilian purposes, Class II standpipes can be used. This is the type of hose cabinet you will see in older buildings. (Photo 1). These cabinets are slowly being eliminated and many jurisdictions have removed their occupant use of a hose.
These do not meet the standards of Class I and Class III standpipes. The connection is 1 1/2 inches with one jacketed, twist-off type nozzle. These can only produce 100 GPM. They should not be used for firefighting. They are not recommended for firefighters. These connections may be found in wall cabinets. The occupant has removed the hose. If you are using a 1 3/4-inch hose, it is recommended that the connection be 2 1/2-inch with a reducer. Keep in mind that Class II connections are limited to pressure and limited GPM.
Standpipes can be divided into two categories: dry and wet. Automatic wet and manual wet are two types of wet systems. The standpipe system is kept hydrated by an automatic wet system. It also has a fire pump that can provide the required pressures. Although manual wet systems retain water throughout the system, they aren’t backed up with a pump. A combination manual wet system and sprinkler system can have enough pressure to supply sprinklers with sprinklers or require a small pump that supplies sprinklers. However, it will not supply adequate hose outlets.