Advanced Special Valves For Gas Sampling Bags    

                                                                  Dalian Hede Technologies Co.,Ltd. 

    Gas sampling bags are important auxiliary consumables for gas analysis. The performance of gas sampling bag can largely affect the accuracy、the reliablity and repeatability of the gas analysis data.The valve is a key accessory to gas sampling bag performance.Valve in long contact with the gas sample inside bag,so the valve material must be chemical resistance、corrosion resistance、no precipitation of organic matter, on reaction with the gas sample,otherwise the valve can pollute the gas sample inside bag.

    Material selection and seal structure determine the performance of the valve.The design of the valve exterior also affects the valve whether to use convenient.The seal structure of special valvs for gas sampling bags are divided into soft seal structure and self-seal structure.
   soft seal structure is adopted the method of soft elastic rubber seal combining with plastic or metal materials to cover and plug to seal the gas sample.Because of adopting rubber seal,soft seal structure can affect chemical resistance and corrosion resistance of the valve,and also can precipitate organic matter pollute the gas sample in bag.  

   self-seal structure is adopted the method of two smooth surface forming tight joint to seal the gas sample. There are materias can form smooth faces such as:

1.Plastic, such as: PE、PP、PC、ABS etc.   2.Metal, such as: copper、stainless steel etc.   3.Ceramics.

    These materials are strong resistance to chemical and corrosion,and no precipition organic matter so no pollution.self-seal structure is more adcanced and more reliable than soft seal structure .

     The film of gas sampling bag is thin soft and low strength,the inflation pressure of gas sampling bag is low(一般使用压力为3～6Kpa，足以将袋内充满气体，使袋子充分鼓起)so it demands the special valves for gas sampling bags must be tight seal and small volume light quality and switch is easy to operate sampling.As a kind of lab analysis consumable,gas sampling bag must be low price to reduce the customer useage cost.So the special valves must have simple and reasonable design structure and advanced perfomance.

    Since1999 our company produced gas sampling bags we invested a lot of money to constantly study of special valves for gas sampling bags,successfully developed 10 kinds of special valves for gas sampling bags:直通塑阀、铜阀、侧向塑阀、旋塞式直通塑阀、旋塞式侧向塑阀、滑管式塑阀、针型塑阀、活塞式塑阀、四氟直通阀、四氟侧向阀。从2005年到2010年已获得国家实用新型专利四项，部分专利已申请美国和加拿大专利。

    2009年我公司设计开发的装配旋塞式塑阀的气体采样袋获得国家实用新型专利，并已申请美国，加拿大的专利。与国内、国外气体采样袋上用的阀门相比有显著的先进性。

    旋塞式塑阀从外形上看，分为旋塞式直通阀和旋塞式侧向塑阀。旋塞式直通塑阀的导气管垂直于袋薄膜平面，旋塞式侧向塑阀的导气管平行于薄膜平面。

    旋塞式塑阀采用自密封结构，通过精密的注塑工艺制造，产品质量稳定适宜大批量生产，能大幅度降低生产成本，与其他类型阀门相比有如下优点：

1、旋塞式塑阀材质为医疗级的PE和PC，耐腐蚀、耐化学品、不析出有机挥发物、不污染气体样品。

2、旋塞式塑阀采用的自密封结构，密封严密、无橡胶密封件与袋内气体接触、不污染气体样品。

3、旋塞式塑阀采用自密封结构，使阀体积减小，阀内腔容积更小，并且内腔结构简单，呈筒状，这样使气体采样袋气体置换更加容易、迅速。特别是旋塞式侧向塑阀，具有快速置换功能，用于气体采样袋气体置换非常方便，充气连接管与旋塞式侧向塑阀导气管接通，气体充入袋内后，打开取样帽，旋转阀扳手，指向取样口，即可放空置换。

4、旋塞式塑阀上装配的硅橡胶取样垫与袋内气体接触通过阀门控制，硅橡胶取样垫与袋内气体为不常开接触，当用进样针取袋内气体时，要把阀门扳手旋转指向取样帽，使袋内气体与硅橡胶垫导通，就可以用进样针取样，当取样结束，再把阀门扳手旋转90度阀门关闭，袋内气体与取样垫断开，打开取样帽可放空。这种设计的作用是硅橡胶取样垫不长时间接触袋内气体，避免袋内气体样品腐蚀硅橡胶垫和气体样品被硅橡胶垫污染。目前，国内和国外的厂家生产的气体采样袋上装配的硅橡胶取样垫与袋内气体都是常开接触。在美国有的公司使用氟塑料膜覆盖在硅橡胶垫上，用以避免硅橡胶垫被腐蚀和污染气体样品。

    通过对国内、国外的气体采样袋用阀门的分析，表明我公司研制的旋塞式塑阀是国际领先的气体采样袋专用阀门，装配旋塞式塑阀的气体采样袋能有效地保证气体采样分析工作的准确性和可靠性。使气体分析采样工作更加方便和有效率。可以确信，装配旋塞式塑阀的气体采样袋是严谨的色谱分析工作人员的首选。