3,根据常用的加热管电阻值Ω国标范围：+5-10％电阻值(公司的标准为:+4-8％计算)=等于出厂电阻，特别说明:按国标是+5-10％,为啥按+4-8％计算,计算时把电阻范围缩小,就是说:在生产中电阻超出+4-8％范围,还在+5-10％范围内,这样不会出现电阻偏大偏小.电阻下限值: 81.3÷1,04=78.1Ω；电阻上限值: 81.3÷0,92=88.3Ω
In the design, the production process heating pipe, heating pipe resistance value, determines the power of a heater（电热管功率）, GB stipulates, electric heating tube power error range and an electric heating pipe resistance error range, the following article I will introduce how to calculate the 1 aluminum heating pipe resistance range value, heating in what range of resistance within the tube to comply with the relevant standards.
1: got the customer’s drawings, understand customer requirements: using voltage: 230V, power 650W+5-10%; the electric heating pipe with computer CAD drawing out, calculate the pipe length: 252mm,
2: calculates the current intensity is A and the electric heating pipe resistance value（电热管电阻值）, I- current intensity of A, P- heat pipe power（电热管功率） W, V- working voltage V, R- resistance, I=P /U; =650/230=2.83A; R=U/I=230/2.83=81.3.
3, according to the common heating pipe resistance value of Omega GB range: +5-10% resistance value (the company standard: +4-8%) = factory resistance special note: according to national standard +5-10%, why is calculated according to +4-8%, the resistance range is narrow, that is: in the production of resistance beyond the scope of +4-8%, still in the range of +5-10% this will not occur, larger resistance is small. The resistance limit: 81.3 / 1,04=78.1 Ω; resistance limit: 81.3 / 0,92=88.3