Although it is not an actuator in itself, a driving form worth mentioning is the process fluid pressure itself driving the valve mechanism. The principle of self operated valves can be used for throttling or on/off applications, gas or liquid services. The process fluid can be piped directly to the actuating element (diaphragm or piston), or the pressure can be adjusted before reaching the valve actuator through a small mechanism called a pilot. The latter design allows the movement of the main valve to be controlled by an adjustable device (pilot).

先導(dǎo)式控制閥的一個非常常見的應(yīng)用是氣體壓力調(diào)節(jié)，特別是對于用于為大型工業(yè)燃燒器提供燃料的燃氣，如丙烷或天然氣。彈簧試圖迫使塞子離開閥座，而來自閥門下游側(cè)的“反饋”氣體壓力作用于柔性隔膜，將塞子移向閥座。良工閥門中下游壓力越小，修剪打開得越多;下游壓力越大，修剪關(guān)閉的就越多。該彈簧為調(diào)壓閥建立壓力調(diào)節(jié)“設(shè)定值”。如果需要不同的設(shè)定點，則必須用具有不同剛度的彈簧替換彈簧。

A very common application of pilot operated control valves is gas pressure regulation, especially for gas used to provide fuel for large industrial burners, such as propane or natural gas. The spring attempts to force the plug away from the valve seat, while the "feedback" gas pressure from the downstream side of the valve acts on the flexible diaphragm, moving the plug towards the valve seat. The lower the downstream pressure in the Lianggong valve, the more open the trim; The greater the downstream pressure, the more pruning is closed. This spring establishes a pressure regulation "set value" for the pressure regulating valve. If different set points are required, the spring must be replaced with a spring with different stiffness.

這個主題的一個變體是先導(dǎo)加載或外部加載的壓力調(diào)節(jié)器，使用外部氣體壓力源來建立壓力調(diào)節(jié)設(shè)定點。在這里，一個簡單的手動調(diào)節(jié)壓力調(diào)節(jié)器用作“先導(dǎo)”裝置，將負(fù)載壓力發(fā)送到主調(diào)節(jié)器的驅(qū)動膜片頂部：外部提供的負(fù)載壓力不是建立調(diào)壓閥壓力設(shè)定點的剛性內(nèi)部彈簧。

A variant of this theme is a pressure regulator with pilot loading or external loading, which uses an external gas pressure source to establish a pressure regulation set point. Here, a simple manual pressure regulator is used as a "pilot" device to send load pressure to the top of the driving diaphragm of the main regulator: the externally provided load pressure is not a rigid internal spring that establishes the pressure setting point of the pressure regulating valve.

由于良工閥門通過轉(zhuǎn)動手動設(shè)置的壓力調(diào)節(jié)器上的旋鈕可以輕松調(diào)節(jié)該負(fù)載壓力，因此主調(diào)節(jié)器現(xiàn)在也可以調(diào)節(jié)。先導(dǎo)機構(gòu)控制主氣體節(jié)流機構(gòu)，因此得名先導(dǎo)。使用先導(dǎo)式的安全閥具有可調(diào)節(jié)性廣的優(yōu)點，而非先導(dǎo)安全閥的調(diào)節(jié)范圍通常有限。

Due to the fact that Lianggong Valve can easily adjust the load pressure by turning the knob on the manually set pressure regulator, the main regulator can now also be adjusted. The pilot mechanism controls the main gas throttle mechanism, hence the name pilot. The use of pilot operated safety valves has the advantage of wide adjustability, while the adjustment range of non pilot operated safety valves is usually limited.