{"id":3202,"date":"2022-07-13T16:52:09","date_gmt":"2022-07-13T08:52:09","guid":{"rendered":"https:\/\/www.hginstrument.com\/?p=3202"},"modified":"2022-07-13T16:52:09","modified_gmt":"2022-07-13T08:52:09","slug":"common-faults-of-pneumatic-control-valve","status":"publish","type":"post","link":"https:\/\/www.hginstrument.com\/it\/common-faults-of-pneumatic-control-valve\/","title":{"rendered":"Guasti comuni della valvola di controllo pneumatica"},"content":{"rendered":"
    \n
  1. Air source failure<\/strong><\/li>\n<\/ol>\n

    \u25b6On-site air supply is not opened<\/p>\n

    \u25b6The air source is watery, the weather is cold and frozen.<\/p>\n

    \u25b6Supply of purified air is stopped<\/p>\n

    \u25b6The air pressure is too low due to the leakage of the air source main pipe or the blockage of the air line, and the control valve cannot be fully opened or fully closed, or even does not act.<\/p>\n

    \u25b6The air filter pressure reducer is used for a long time, and there is too much dirts. The black knob under the pressure reducing valve opens and leaks air, so that the output air pressure is lower than the specified pressure, which results in the regulating valve not being able to be fully opened and fully closed, or even not acting.<\/p>\n

    \u25b6The on-site air line leaks air, and the joint is loose, which results in insufficient air pressure, and the control valve cannot be fully opened or closed, or even does not act.<\/p>\n

    \u25b6The failure of the filter pressure reducing valve causes the wind pressure to be unstable and causes the regulating valve to oscillate.<\/p>\n

     <\/p>\n

      \n
    1. Line failure<\/strong><\/li>\n<\/ol>\n

      \u25b6 The wiring terminals of the power cable are loose, fall off, short-circuited; or open-circuited, too much dust on the circuit board results in poor contact; signal fluctuation and vibration of the control valve.<\/p>\n

      \u25b6 After heavy rain or typhoon, the equipment is wetted by water which cause wiring to be short-circuited, result in the control valve unable fully opened or fully closed.<\/p>\n

      \u25b6 Reverse polarity will cause the control valve to not act.<\/p>\n

      \u25b6The middle section of the power cable is faulty due to the failure of the insulating tape; The wire insulation leather peels off causing a short circuit between wires; due to the on-site vibration, the wire is broken, results in the discontinuous action of the control valve, cannot fully open or fully close or even does not act.<\/p>\n

      \u25b6 Failure of the regulating valve due to incorrect wiring after the regulating valve has been repaired<\/p>\n

      \u25b6 The output signal of the control valve is unstable, which causes the operation of the control valve to fluctuate.<\/p>\n

       <\/p>\n

        \n
      1. Positioner failure<\/strong><\/li>\n<\/ol>\n

        \u25b6 The fixed nut of the feedback rod is loose and falls off, or the spring on the feedback rod falls off, causes the feedback rod to loosen, fall off, and jam, causes the regulating valve to oscillate.<\/p>\n

        \u25b6 The position sensor in the positioner is faulty. When the vibration reaches a dead point, it will cause the central control room to display overt-ravel, and it will return to normal after a while, which can be solved by replacing the position sensor.<\/p>\n

        \u25b6 The PID parameter setting of the positioner is not suitable.<\/p>\n

         <\/p>\n

          \n
        1. Valve body failure<\/strong><\/li>\n<\/ol>\n

          \u25b6 The valve spool or valve seat of the control valve is worn (scouring of the medium, rust, welding slag and other dirt), jamming (be blocked by all kinds of impurities in the medium), and the sealing is not tight (the sealing ring is worn), resulting in the media is still in excess when the valve is fully closed, it cannot be controlled.<\/p>\n

          \u25b6 The control valve disc is pressed too tightly or too loosely, if too tight, it will make the valve stem move slowly or jump; if too loose, it will cause the medium to leak. if the medium is heavy oil, it is likely to burn and cause a big accident.<\/p>\n

          \u25b6 When the control valve is installed, the pipeline and the valve body are not concentric, it make that the control valve is subjected to excessive additional stress, results in vibration, the valve can not full open or fully close.<\/p>\n

          \u25b6 The valve stem of the control valve and the fixing nut of the connecting part are loose, and the valve stem and the valve spool are not concentric, which causes the valve to not fully close, and the subjected stress increases, results in the valve stem high frequency oscillation, or even fracture.<\/p>\n

          \u25b6 The diaphragm head of the control valve is faulty. Due to the long-term use of the diaphragm, the aging and deterioration, the reduction of elasticity, the poor sealing performance, the leakage of the diaphragm, the aging of the compression spring, the reduction of elasticity and the breakage, result in the control valve cannot fully open and fully close or even out of control. The valve spool of the control valve falls off, the valve spool and the valve seat are stuck, and the valve stem is bent or broken, which will cause the control valve to operate abnormally, can not play a role of regulating.<\/p>","protected":false},"excerpt":{"rendered":"

          La valvola di controllo pneumatica utilizza l'aria compressa come fonte di energia, il cilindro come attuatore e aziona la valvola con l'aiuto del posizionatore, dei convertitori e di altri accessori per realizzare la commutazione o la regolazione proporzionale e accetta il segnale di controllo del sistema di controllo dell'automazione industriale per regolare il flusso, la pressione, la temperatura e altri parametri di processo del fluido nella tubazione. Attualmente, le valvole di controllo pneumatico sono ampiamente utilizzate nei settori petrolchimico, dell'energia elettrica, della metallurgia e di altre industrie di processo e costituiscono un elemento indispensabile e importante del sistema di controllo. Pertanto, \u00e8 molto importante garantire un funzionamento stabile e affidabile della valvola di controllo pneumatica. Quando la valvola di controllo pneumatica si guasta, pu\u00f2 essere controllata in base ai guasti comuni della valvola di controllo, per trovare in tempo la causa del guasto.<\/p>","protected":false},"author":1,"featured_media":2768,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[2130],"tags":[],"acf":[],"_links":{"self":[{"href":"https:\/\/www.hginstrument.com\/it\/wp-json\/wp\/v2\/posts\/3202"}],"collection":[{"href":"https:\/\/www.hginstrument.com\/it\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.hginstrument.com\/it\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.hginstrument.com\/it\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.hginstrument.com\/it\/wp-json\/wp\/v2\/comments?post=3202"}],"version-history":[{"count":0,"href":"https:\/\/www.hginstrument.com\/it\/wp-json\/wp\/v2\/posts\/3202\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.hginstrument.com\/it\/wp-json\/wp\/v2\/media\/2768"}],"wp:attachment":[{"href":"https:\/\/www.hginstrument.com\/it\/wp-json\/wp\/v2\/media?parent=3202"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.hginstrument.com\/it\/wp-json\/wp\/v2\/categories?post=3202"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.hginstrument.com\/it\/wp-json\/wp\/v2\/tags?post=3202"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}