Fire hose adapters are small but essential components that reduce firetrucks’ weight and enhance their level of preparedness
Fire trucks in the United States are oftenlarge-size vehicles like giant
multi-wheeled toolboxes carrying not only firefighters, but also tons of hoses, bunker gears, and water.On fire engines, small gears such as fire hose adapters and fittings play a key role in reducing firefighters’ loads to work much lighter and smarter.
If you are looking for the right hose adapter, the best move is to shop around and do some homework to know how each fitting differs before buying. Here is your homework.
Thread types determines hose connection flexibility
Like conventional mating connectors, each of most hose fittings and adapters has a matching gender (a male or female thread) for one to connect with the other. That means the angle (pitch), spacing, and diameter ofeach thread varies widely, depending on thread styles. Mismatched thread types may cause fittings to leakor even burst off under pressure, posing serious risks to both firefighters and potential victims.
Despite regional ramifications of thread types, fire hose adapters typically meet the following most popular standards:
- Most popular: National Standard Thread/National Hose (NST or NH)
- Less popular: National Pipe Straight Hose/Iron Pipe Thread (NPSH or IPT)
- Wildfire firefighting and special uses: Garden Hose Thread (GHT)
- Fixed piping system/pressure gauge connections: National Pipe Thread (NPT)
Fittings with National Pipe Thread (NPT) cause the most controversy in the field of fire protection. The main reason is that NPT threads can screw with other NPT threads permanently while male NPT threads attach to NPSH fittings onlytemporarily. It takes a male NPSH fitting and a female NPT fitting to make a permanent connection. Here are two simple rules for NPT-threaded users to follow:
1. Connect male NPT ends to NPSH fire hoses or female NPT-threaded pipes.
2. Connect female NPT ends only to male NPT ends for permanent installation of fire pumps or piping systems.
Each fire equipment has its own thread gender
The thread gender (male/female) of hose fittings and adapters only connect to mating inlets or outlets of the fire equipment. Generally, the equipment that discharges water has male-threaded outlets as garden hoses have while the orifices that receive water have female threads or female swivels.
Although local fire departments are given considerable autonomy by the authorities over how to pick their own equipment and threads, they still adhere to certain conventional guidelines on gendered connections describedin a nutshell as follows:
Fire hoses, with a male coupling and a female one at each end, enable firefighters to link hoses together if need be. Female swivels are used by Fire Department Connections (FDCs), which means only male-ended fire hoses can be connected to FDCs for sprinklers and standpipe systems to be supplied with water.Here are some handy hints about such connections:
1. Fire hose nozzles with female inlets should connect to fire hoses with male ends.
2. Fire hydrants have male-threaded outlets or nozzles.
3. Dry hydrants, unpressurized pipes with one end below the water level of a pond or lake, can have either male or female threads, depending on how they are installed in the rural locations worldwide.
4. Hose angle valves, an integral part of permanently installed indoor hoses, have either male- or female-threaded outlets.
5. Swinging hose racks, to attach to a double-male nipple, typically have the hose valves with female-threaded inlets.
6. Stationary hose angle valves, often found with a rack and reel hose, may use male-threaded outlets.
Fire hoses and equipment without threads
So far, we have talked considerably about the threaded fire hose adapters and fittings commonly seen on the fire protection system markets. Now we would like to mention the threadless couplings used by many hoses, valves, and pumps — Storz connections, which have been widely used in Europe for decades and gained increased visibility in the United States recently. ThoughStorz couplings come in large and small sizes, the US fire departments prefer 4” and 5” sizes on the following equipment:
- Fire hose couplings
- Fire department connection inlets
- Inlets and outlets on tankers or engines
- Largediameter “pumper nozzles” on fire hydrants
Certain adapters provide good connection with different threaded fire equipment
We learned the peril of incorrect fittings the hard way when Oakland Hills Fire devastated Oakland, California in 1991.The major reason why the fire grew to an enormous scale at such a rapid pace is that the firefighters called on from neighboring communities failed to connect their standard 2 1/2″ adapters to Oakland’s 3” hydrant connections.
We’ll further discuss in this section how to prevent connector mismatch in similar situations, such as:
- Firefighting units from neighboring jurisdictions combine forces (mutual aid operations)
- Newly acquired or donated equipment fail to connect to existing equipment
Storz x 4 1/2″ NST
Usage:provide the connection between standard 4 1/2″ hydrant inlets and large-diameter Storz hose.
Swivel Adapters – 1 1/2″ or 2 1/2″ Female NST to Male NPT (Various)
Usage: connect the swivel end of an NPSH hose to an NST-threaded hose (male), NST hoses to NPSH nozzles, or an NPSH-threaded hose to an NST-threaded port on a fire pump.
- 1 1/2″ FNST x 1 1/2″ MNPT
- 2 1/2″ FNST x 2″ MNPT
Hex Adapters – FNST x MNPT (1 1/2″ & 2 1/2″)
Usage: connect the male end of the NST hose to the female end of an NPSH hose or fitting; NST hoses to NPSH nozzles, NST, and NPSH hoses; and NPSH hoses to NST pumps.
- 1 1/2″ F NST x 1 1/2″M NPT
- 2 1/2″ F NST x 2 1/2″ M NPT
Fire hose fittings and adapters can perform a reverse lay much quicker
Fire engines are designed to carry hundreds of feet of fire hoses in length that would need to be handled and storedby firefighters in various ways from the “flat load” to the “reverse horseshoe” according to fireground situations.It’s not uncommon for a hose to be stored in the wrong direction, or for the wrong end of it to be pulled from the engine. Fire hose fittings and adapters can always be used to correct this problem without re-laying the hose.
2 1/2″ Double Female NST
Standard uses: Connect mislaid hoses to each other or to hydrants more quickly due to swivels that many double-female adapters have.
2 1/2″ Double-Male NST
Standard uses: Connect mislaid NST hoses to fire department connections, such as nozzles, engines, and other hoses.
Other firefighting adapters for long-term installation
It would be idealistic to think all hydrants and hoses are so compatibly arranged that there is no chance of them being mismatched anyway. In practice, however, some adapters are installed permanently to avoid such mismatches and ensure firefighters always have access to water.
Hose Rack Brass Nipples (1 1/2″, 2 1/2″ NST)
Standard uses:This type of nipples is identical to most other double-male adapters except that they are longer in length and have the hex-shaped protrusion. Such features help the nipple to reach through an orifice in a swinging hose rack, thus holding the angle valve and fire hose together.
Sizes: 1 1/2″ pin racks are typical of Class II standpipe systems and some Class III systems. Other class III systems mayhave larger (2 1/2″) angle valves for firefighters’ 2 1/2″ hose or 1 1/2″ permanent hose (via a 2 1/2″ x 1 1/2″ reducer). All in all, here are the typical sizes for this type of nipples:
- 1 1/2″ MNPT x MNST – Class II and Class III systems with 1 1/2″ pin racks
- 2 1/2″ MNPT x MNST – those Class III systems with 2 1/2″ hose angle valves (reducers required)
Hex Adapters – 1 1/2″ or 2 1/2″ Double Female, Double Male, and Male x Female
Standard uses:This type of adapters permanentlyconnect pipes, pumps, and the equipment with NPT orifices to fire hoses.
Sizes and types: Conventionally, inlets are the pipe or orifice with female NPT threads while outlets are those with male threads. The fittings that connect to NPT outlets are listed as follows based on the hose threads and the matching adapters:
Fire protection fittings and adapters may look complex at first sight
So far, you have glanced through standard uses of various adapters we presented concisely, but they are not the golden rules. A little bit creativity may make a huge difference in joining all sorts of right equipment together in no time. But you must be very careful while choosing the right equipment or adapters.Firefighters can be delayed and, worse still, their efforts might even fail due to mismatched adapters.