How to avoid local aging caused by long-term indentation when the fire fighting agricultural belt is folded for storage?
Publish Time: 2025-03-25
During the long-term storage of the fire fighting agricultural belt, the indentation formed at the folding part not only affects the smooth flow of water during use, but also accelerates the local aging of the material, eventually leading to cracks or even bursts. This kind of damage caused by improper storage is often hidden. When the water hose suddenly fails during emergency use, the consequences may be very serious. To avoid this problem, it is necessary to start from three aspects: material properties, folding method and environmental control.
The memory effect of the material is the inherent cause of indentation aging. Whether it is PVC, TPU or rubber lining, polymer materials will creep under continuous pressure-the molecular chain gradually slips and forms permanent deformation. Experimental data show that when the water hose is stored in a folded state for more than three months, the tensile strength of the compressed area will decrease by 15%-20%. What's more tricky is that these indentations will become stress concentration points, inducing microcracks to expand when the water hose is pressurized. In view of this characteristic, modern hoses have begun to use composite rubber materials with higher elastic recovery rates. Their molecular cross-linked structure can rebound faster after the pressure is released, reducing the residual rate of indentation by more than 40%.
The optimization of the folding method directly determines the pressure distribution. Although the traditional "Z" folding method saves space, it will form sharp creases at the corners. The improved "roll-type coiling" rolls up the hose in a circular ring with a diameter not less than 8 times the width of the hose itself, so that the bending stress is evenly dispersed. The NFPA 1962 standard of the National Fire Protection Association specifically stipulates that hard folding at any angle should be avoided when folding and storing. It is recommended to use "8-shaped" alternating stacking. This method can reduce the stress time of each bending point by half. For large-diameter hoses (≥65mm), professional fire brigades will use special tape winding machines to ensure that each circle maintains the same tension and avoid local overpressure.
The temperature and humidity control of the storage environment is also critical. High temperature will significantly aggravate the stress relaxation of polymer materials. When the warehouse temperature exceeds 35°C, the depth of the indentation produced under the same pressure will increase by 50%. Therefore, the ideal storage environment should be controlled between 15-25℃ and the relative humidity should not exceed 60%. Some advanced warehouses use a suspended three-dimensional storage system to allow the hose to hang naturally and completely eliminate the folding pressure. Under field conditions, at least the hose should not be directly in contact with the ground, separated by a breathable bracket, and regularly (recommended every two months) unfolded and re-reeled to change the pressure position.
The use of protective accessories provides additional protection for the hose. Silicone pads are the simplest solution. Inserting this soft, high-rebound material between the folded layers can disperse the contact pressure to a larger area. A more professional approach is to use honeycomb buffer cardboard, whose hexagonal structure can absorb more than 80% of the concentrated stress. Some fire stations in Europe have begun to use inflatable storage bags, which keep the hose in a cylindrical shape through the internal airbag support. This innovative design keeps the hose in a "zero indentation" state during storage.
Regular testing is the last line of defense against aging. Ultraviolet light irradiation can visualize micro cracks in the indentation area, and portable hardness testers can quantitatively detect changes in Shore hardness at the fold. When it is found that the hardness of a section of water hose is more than 15 points higher than the normal value, this area has entered the accelerated aging stage and should be marked immediately and used first. The German Fire Department has even developed an AI-based image recognition system that automatically compares the expansion trend of the indentation by regularly taking photos of the surface of the water hose.
The combined application of these measures has extended the service life of modern fire fighting agricultural belts from the traditional 3-5 years to more than 7 years. When the water hose is taken out of the warehouse and unfolds its body smoothly like a giant python, those invisible protective details are silently guarding the youthful vitality of every inch of the pipe. In the battle against time, the combination of scientific storage methods and advanced materials allows these emergency rescue "lifelines" to always maintain the best combat status.
