Experts, I have another question regarding valve selection and would appreciate your advice!
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Recently, I encountered a problem when selecting components: what is the difference between a \"mechanical limit stop\" and a \"limit switch\"? I know that a mechanical limit is something like a clip at the valve actuator that prevents it from opening or closing completely. But what exactly is a limit switch? I remember it also had a limited range. And I know that limit switches also come in mechanical and proximity types. I’m really confused now; the information I found online about limit switches only makes things more unclear to me.
A limit switch is a limit switch box with an integrated structure. It features a window that allows for clear observation of the valve’s on/off status, as well as remote transmission of signals regarding the valve’s position. It is equipped with built-in mechanical or proximity limit switches, and the limits can be adjusted quickly using cams. Its compact design ensures reliable operation; it serves as a common accessory for pneumatic actuators.
Recently, I encountered a problem when selecting components: what is the difference between a \"mechanical limit stop\" and a \"limit switch\"? “A “mechanical limit” is, as the name suggests, a mechanical device that uses physical means to hold the actuator in a pre-set position, which can be adjusted as needed. “A \"limit switch\" is an electrical signal-based positioning device with a preset limit position. When the actuator moves to this preset position and activates the microswitch on the limit switch, the microswitch operates, and this signal is sent to the control system (or control panel/cabinet). The control system, while displaying the valve position, issues a stop command to the actuator, causing it to halt at that position, thereby achieving the purpose of limiting its movement. The main difference between the two types of limits is that one is a mechanical limit device, while the other is an electrical signal limit device.
This post was last edited by Hariky on 2018-2-4 22:18. 【Mechanical limitation】 involves the use of mechanical components such as bolts and washers to restrict the movement of the actuator, thereby limiting the degree of valve opening. It is divided into maximum mechanical limit and minimum mechanical limit. A 【limit switch】, also known as a feedback switch or valve position feedback switch, is typically installed at the fully open and fully closed positions of the valve; it sends a \"on/off\" status signal back to the control system when the valve is in either of these positions. Note: There is another type of limit, namely a soft limit, which involves setting limits on the output value of the valve within the control system, or setting limits on the opening degree in the valve positioner. The reliability of these two methods is highly affected by failures in system or line components, and they are not used in safety-related applications. Such as when the control valve is relevant to the calculation of the downstream safety valve.
Both have limits; this is the position where the effect is limited； Mechanical limits are not necessarily used as switches; they merely serve to define positions. A switch, as the name implies, exists in two different states, and it involves the detection of status signals ； Also, there is a big difference between mechanical limiting and mechanical means; one should not assume anything without considering this ； Do a good job with classification and focus on your own understanding.
Thank you! Now that you put it that way, I understand
Thank you! One electrical signal, one physical limitation~