What is the difference between regulation and linkage? How should one distinguish them? ?
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For example, using a steam control valve to regulate the heating temperature: normally, when the temperature rises, the control valve should be closed down. Is this considered a feedback loop? When the high temperature alarm is triggered, the control valve should close – is this a form of interlocking? For example, when the liquid level is low, the feed valve needs to be opened – is this a feedback mechanism or just regulation? And when the liquid level is high, the feed valve needs to be closed – is this also a feedback mechanism? If the high liquid level alarm goes off, it needs to be shut off – is this part of a interlock mechanism? ? Where is the boundary between regulation and franchising?
This post was last edited by ylb913 on 2016-6-16 at 11:07. Adjusting a control valve through the normal opening and closing of a positioner is not considered interlocking. The chain is usually controlled by solenoid valves. In the case of using a pneumatic control valve with interlocking, a two-position three-way solenoid valve is installed in the instrument air line behind the positioner; this valve is used to interlock and cut off the instrument air, enabling the control valve to close or open quickly.
The focus of interlocking is on safety, while the focus of regulation is on process control. Pneumatic cut-off valve for interlocking, fast-acting, with only two positions: open and closed. Pneumatic control valves for regulation have slow response and can have an infinite number of valve positions.
Adjustment is a set of operations to keep the process parameters at normal values； Interlocking is a set of operations under abnormal conditions.
What you mentioned all falls under regulation, not interlocking. Interlocking is generally a circuit for providing safety protection; it is typically used to control two-position cut-off valves once certain interlocking conditions are met
Sir, can a pneumatic control valve equipped with a solenoid valve be used as a interlock? Can’t electric control valves be used for interlocking then? Thank you for your answer!
Also, generally speaking, when the temperature remains high and the control valve closes, does this situation fall under the category of interlocking or under the category of control?
Simply put, regulation is a requirement for the manufacturing process, while interlocking is a requirement for safety. In a chain reaction, once a signal exceeding the threshold value is detected, the system will be forced to stop operating; it can only resume operation once the unsafe condition has been eliminated.
Sir, it’s like adding material when the liquid level is low – does this fall under a feedback loop? If the liquid level is too high, feeding should be stopped – does this also fall under interlocking? Thank you!
Sir, it’s like adding material when the liquid level is low – does this fall under a feedback loop? If the liquid level is too high, feeding should be stopped – does this also fall under interlocking? Thank you!
The chain is meant to stop the system from operating; if the system stops, that’s a chain reaction, and if it doesn’t stop, then it’s just regulation.