Recently, GB/T 24798-2009 "rubber seals for solar hot water systems" (hereinafter referred to as "national standards for aprons") was formally implemented.
The “National Standard for Aprons†puts forward requirements for the materials, dimensions, tolerances and appearance quality of the aprons, and also the physical properties such as hardness, tensile strength, elongation at break, heat resistance, and ozone resistance. Specific performance requirements. The rubber liner material of the inner liner specified in the standard is silicone rubber, and the outer cylinder apron can be made of silicone rubber and EPDM rubber. "Using bad materials to make aprons will affect the product's lifespan and reliability, and it will also have a bad influence on the solar water heater's entire machine." Similar to Zhang Lifeng, in the increasingly competitive solar water heater market, Machine companies have become increasingly demanding on the performance of accessories.
Gao Jingru said: "Silicone rubber and EPDM rubber are synthetic rubber products, because of the different uses of the inner liner and the outer cylinder apron, the selected materials are also different. Because the inner liner and the tank Water contact can be made using silicone rubber with good hygienic properties; EPDM rubber has better physical and mechanical properties and better sealing performance. It can also be used as a material for outer cylinder aprons.â€
In addition, unlike metal parts, rubber parts have large tolerances and are positive tolerances. "The interference force generated by the compression of the apron and the vacuum tube can make the two closely combined." Gao Jingru pointed out the reason for the positive tolerance. "Electrical" reporter noted that due to the large changes in the ambient temperature of the apron, the standard prompts should pay attention to the thermal expansion of the apron.
As one of the accessories for solar water heaters, the introduction of the apron standard will not only improve the quality and reliability of the apron, but also improve the interchangeability of different brands of aprons. Although the apron is only a small part of the solar water heater, it will have a great impact on the thermal efficiency of the solar water heater. If the apron is easy to age or loose, the heat loss of the solar water heater will increase, which will affect the thermal efficiency of the whole machine.
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