進口自力式調節閥的選用
進口自力式壓力調節閥因為不需要其它外來能源如電源、氣源，僅靠介質自身的能量來驅動，既節能又環保，使用方便，安裝完畢后設定好壓力值即可投入自動運行，所以在對控制精度要求不高，又缺乏電源、氣源的場合，得到了越來越廣泛的使用。美國威盾VTON主要有用于調節流量的進口自力式流量調節閥，用于調節溫度的進口自力式溫度調節閥，用于控制壓力的進口自力式壓力調節閥，
不過，這種閥門也需正確選型和正確安裝、使用，才能保證投入運行后不出現什么問題。選型方面就不用多說了，比如調節閥是用來控制閥前壓力（控制閥前壓力調節閥）閥后壓力（控制閥前壓后調節閥），介質是常溫還是高溫，有無腐蝕性，最高工作壓力等等，一定要事先搞清楚，我們主要談談安裝使用方面的問題。因為我最近碰到一例自力式壓力調節閥的使用方面出現的問題，很有代表性。 閥門是用在蒸汽管道上的，投入使用才短短一兩個月，用戶就報修。到現場一看，大量蒸汽從調節閥膜頭的排氣孔中排出，噪聲極大，聲勢驚人。事故原因，明顯是蒸汽沒經過冷凝，直接進入膜頭，燒壞了膜片。 用于蒸汽管道的自力式壓力調節閥，安裝時必須在執行器和管道之間加一個冷凝罐，不能讓蒸汽進入執行器膜頭，而且，調節閥必須頭朝下安裝，冷凝罐要高于膜頭，初次使用，一定要將冷凝罐和膜頭中加滿水。看現場的安裝方式，詢問現場儀表人員，這些都沒問題，那么是什么造成的呢？令人百思不得其解。后來，仔細詢問了一個操作工，無意之下得知：這臺閥門安裝、投入使用后，冷凝罐和膜頭之間的銅管接頭一直在斷斷續續地漏水。原來是這樣，漏水導致冷凝罐里的水慢慢漏光，蒸汽就進入膜頭，燒壞了膜片。 由此可見，自力式壓力調節閥在蒸汽管道上使用時，安裝、維護方面一定要多加注意，為保證調節閥正常運行，千萬不能讓接頭漏水，不能讓冷凝罐缺水，要定期檢查，適時加水。其實，不光是自力式壓力調節閥，就是其它的自力式調節閥，在使用時也需注意維護和保養才行。 另外，蒸汽壓力如果較高，最好選用活塞式執行器，而不取薄膜式執行器，因為膜片一般能承受的壓力不超過0.4Mpa，過此雖然能用，卻要大大降低使用壽命。
尤其要提到的是當要控制的壓力低于5kp的時候，要選用帶指揮器的自力式壓力調節閥，此閥門主要用于微壓的控制，氮封裝置場合。
Self-pressure regulating valve used Self-pressure regulating valve because there is no other external energy sources such as power, gas supply, relying on the media's own energy to drive, both energy saving and environmentally friendly, easy to use, after installation you can put pressure value set to run automatically, so in the control accuracy is not required, the lack of power, gas supply of the occasion, has been more widely used. However, this valve also need the correct selection and proper installation, use, put into operation to ensure there are no any problems. Needless to say the selection of areas, such as the control valve is used to control valves or valve before the pressure after the pressure medium is at room temperature or high temperature, with or without resistance, the maximum working pressure, etc., must first find out, we mainly discuss the about installation problems. I recently came across one case of self-pressure regulating valve used in problems, very representative. Valve is used in the steam pipe, and put into use until a month or two, the user repair. To the scene and saw a lot of steam control valve membrane from the vent in the discharge head, a great noise, momentum amazing. Cause of the accident, was not through the condensation of steam directly into the membrane head, burn the diaphragm. Self-piping for steam pressure control valve must be installed between the actuator and pipe plus a condensation tank, can not let the steam into the head actuator membrane, and the control valve must be installed upside down, condensate tank is higher than film head, initial use, be sure to head in the condensate tank and fill the water film. Look at the installation site, ask live instrumentation personnel, these no problem, then what is causing it? Baffling. Later, asked in detail about an operator, under the intention that: this valve is installed, put into use, condensate tanks and brass fittings between the first film has been leaking intermittently. The original is the case, leading to condensation tank leaking slowly leaked water, steam enters the membrane first, burn the diaphragm. Thus, the self-pressure regulating valve used in the steam pipe, installation, maintenance must pay more attention to ensure the normal operation of control valve, do not let joint leakage, condensation can not allow water to regular inspection, timely add water. In fact, not only is the self-pressure regulating valve, is that other self-regulating valve, when in use also need to pay attention to maintenance and maintenance of the job. In addition, if a higher vapor pressure, the best selection of piston-type actuator, rather than take the film actuator, because the pressure diaphragm is generally no more than 0.4Mpa, although this can be used too, have greatly reduced service life.