低阻力倒流防止器对水质污染控制意义-专业论文-中国工控网（The significance of low resistance backflow preventer to water pollution control）.doc

低阻力倒流防止器对水质污染控制意义-专业论文-中国工控网(The significance of low resistance backflow preventer to water pollution control)
The significance of low resistance backflow preventer for water pollution control
1 Overview
Backflow preventer is an effective protection of the quality and safety of water tap water facilities, has been widely used in some developed countries; in our country, especially in twenty-first Century, due to the rapid development of city construction, the rapid increase of the number of users tap water, tap water and water quality requirements continue to increase, backflow preventer is gradually attention and promotion the use of CJ/T160-2002; 2002 issued a "standard" backflow prevention industry, released in 2003 "GB50015-2003" code for design of building water supply and drainage in the national standard provisions of the "reverse flow prevention device" of the occasion and resistance performance requirements.
Backflow preventer, mainly used for municipal water work and the work, or the effective partition between life water and fire water, air conditioning water, green water in different water system; the main function is in the valve closed, there are all kinds of possible leakage, prevent medium leakage port of poor water quality to import water quality is good in the end, to avoid pollution, should be equipped with internal leakage induction and sewage drainage
device.
Introduction to the history, structure and performance of 2 backflow preventer
Backflow preventer originated from check valve, but it is essentially different from check valve.
Figure 1 the first generation of products, namely double check valve type backflow preventer, figure 2, the second generation of products, namely, pression type backflow preventer
backflow preventer with double check valves
bination device posed of two check valve series; play a dual role of insurance, in check after the closure of the existing single check valve seal leakage, can ensure the sealing pe