Firefighters are accustomed to using flexible, durable and lightweight hoses. However, many people don’t know that these hoses aren’t fire-resistant.
A team of researchers at Worcester Polytechnic Institute is working on a fire-resistant hose. They are using PTFE, perfluoroalkoxy alkane or fluorinated ethylene propylene to make the hose. This research will hopefully meet aerospace standards.
1. High Temperature Resistance
These hoses are used to protect electrical cables, wires and other equipment from high temperature environments, such as in steel plants, smelters and glass factories. They can also be used to protect hydraulic and oil lines.
These hoses are composed of a polyester jacket and rubber lining. The polyester jacket is woven with warp in polyester staple and weft in polyester filament. The lining is made of natural rubber or PVC. It is lightweight, flexible and has good resistance to rolling and ageing. A radially outer second rubber layer is added for contact protection with the external conditions.
2. High Pressure Resistance
Fire-resistant hoses are designed to work under high pressure. They are also able to resist abrasion, cutting, gouging, corrosion, weather and oil. They are made of silicone materials that don’t encourage electrical conductivity and have low toxicity levels.
In some applications it is advantageous to provide a protective radially outer second rubber layer which is sacrificial in the event of a fire. Such a layer also acts to prevent the contact between the external conditions and the heat resistant inner rubber cover layer.
With collar 302 crimped in position to radially entrap layers 101 to 105 against spigot 301, the present hose assembly is configured to be resistant to elevated internal pressures within bore 106 which might otherwise axially force the end fitting 300 from the hose 100.
3. Flexibility
Fire hose reels allow their users to control and extinguish fires up to 10 times faster than they could with their hands. This makes them a valuable addition to any fire protection system in steel, smelting, shipbuilding, chemical, and other high-temperature areas, oil pipes, rolling mill cables, electrical voltage equipment, large buildings, hydraulic systems, automobile wiring harnesses, and more.
The lining of a fire-resistant hose remains flexible even when exposed to extreme temperatures, unlike other hoses that lose flexibility and may cause injuries. This flexibility helps to reduce accidents and ensures that the hose will perform properly when it’s needed in an emergency situation.
The inner layer of a fire-resistant hose is made from a rubber or polyurethane material. A helix of steel wire is woven into the material. The helix helps to strengthen the hose and provides flexibility for use in various applications.
4. Low Smoke Generation
Fire resistant hoses must meet many different physical property requirements, including burst pressure, cold flexibility and oil resistance. They also need to be durable and reliable to withstand repeated use, high temperatures and harsh conditions.
The new fire retardant rubber compositions and hoses developed by FIRELI can meet these rigorous standards and provide exceptional fire resistance. They can achieve very low smoke density during burning and are self-extinguishing. They can also maintain a high limiting oxygen index (LOI) during operation and are halogen-free and heavy metal free.
The hoses can be made with any type of rubber, such as polyvinyl chloride nitrile butadiene (PVC/NBR) or ethylene-propylene-diene terpolymer (EPDM). They are also coextruded through a polyester textile wave, making them more flexible and lighter than traditional fire-fighting hoses.
5. Low Toxicity
Fire-resistant hose does not degrade over time as rubber does, and maintains its flexibility even after extended exposure to high heat. This is an important feature from a safety and performance perspective.
This special hose meets stringent fire resistance standards. It has a low smoke density, is self-extinguishing when on fire, and has a high limiting oxygen index. It is also halogen-free and heavy metal free, and is electrically insulating.
Wet spray SFRM is mixed with water and applied using a pump and hose system, in a manner similar to paint. It is then allowed to dry. The NFCA provides guidelines detailing the proper application, preparation, repair methods, and safety issues for both wet and dry SFRM. The NFCA also offers guidance for spraying in hazardous areas, and for use with non-flammable surfaces.
