Vegetables and Ornamental Horticulture : Reducing Fire Risks Associated with Shade Cloth

Reducing Fire Risks Associated with Shade Cloth

By Ralph Freeman, Cornell Cooperative Extension

Garden center, nursery and greenhouse fires can be especially destructive due to an extremely flammable material that's commonplace throughout the structures -shade cloth.

Shade cloth can be easily ignited. A spark from welding, contact or even close proximity to a heater, a wiring short circuit or nearby use of battery charging equipment can all ignite shade cloth. Once underway, a fire can then spread very quickly through a facility , rapidly reaching other flammable materials in the structure. Such a rapidly spreading fire can place employees and firefighters at great risk for serious injury . In addition, because of shade cloth's composition of nylon, plastic and aluminized materials, it can begin to "drip" at very high temperatures. Dripping shade cloth can cause damage to plant products, ignite
other flammable materials below it, and/or destroy irrigation systems. Despite the risks, however, shade cloth is a critical component of effective nursery management because of its ability to ensure the proper environment for healthy plant growth by preventing over-heating and plant burn. However, owners should review and implement steps to minimize fire risks that can be associated with shade cloth.

Risk Management Planning

Flame-resistant shade cloth is available and should be considered as a potential option by every grower. This material does not ignite as readily as ordinary shade cloth, but it is not totally fire-retardant.

Because the flame-resistant product often is nearly twice as expensive as traditional shade cloth, many owners feel that its cost is prohibitive. As an alternative, some shade cloth vendors have recently begun to suggest that flame-resistant panels be alternated within the shade curtain system to create "fire breaks". It should be noted that there are no laboratory tests to verify the effectiveness of this procedure. Another approach is to construct firewalls made of noncombustible materials within the system.

In addition, all growers should incorporate basic fire prevention strategies with risk management steps specifically addressing shade cloth:

• Place proper fire fighting equipment in each structure. ABC dry chemical fire extinguishers (5 to 10 pounds) should be used, with the number of extinguishers depending on the size of the building. Travel distance to a fire extinguisher should be no greater than 75 feet.
• Under no circumstances should garden hoses be considered adequate for fire extinguishing in a structure with shade cloth in place to protect plants. A garden hose is 1/2 inch in diameter, as opposed to 2-1/2 inch for a fire hose. This renders a garden hose completely ineffective for addressing extremely fast-buming fires that may occur
  once flames or sparks reach shade cloth.
• Ensure that heating exhaust pipes are always at least three feet from shade cloth. Ideally, use double-walled vent pipe, labeled as "Class B gas vent". At the very least, a metal thimble should be used where the vent passes through combustible
  material, such as a greenhouse end wall.
• Install and maintain smoke alarms in all greenhouses
• Post emergency numbers near all telephones
  

Employee Communication andFire Prevention

Make certain training of all greenhouse employees ensures that they:

• Understand the seriousness of fire risks related to shade cloth.
• Are aware of the locations of all fire extinguishers in the facility and know how to operate the extinguishers.
• Know that the shade curtain should be retracted if a fire should start in order to reduce the risk of fire spread.
• Understand the need to evacuate the facility quickly if immediate steps to contain and extinguish the fire are not effective.
• Know that even if a fire appears to have been put out with immediate application of a fire extinguisher, firefighters should always be called to investigate the situation.
  

Preventive Strategies

Hot work (welding) in a greenhouse can be an especially high-risk situation in terms of potential fire disasters in facilities with nonflame-retardant shade cloth. When welding or other hot work must take place, a "fire watch" is vital. The person designated as the fire watch should have no other responsibilities while the project is ongoing, should remain on duty and alert at all times when equipment is in use and should have a fire extinguisher readily available at all times.

Owners of growing operarations that for any reason may require hot work on a regular basis should give serious consideration to investing in flame-resistant shade cloth.

A well-planned fire prevention program that addresses the special concerns associated with shade cloth can help growers avoid disastrous fires. Ongoing vigilance on the part of owners and employees will continue to minimize risks.