This is the first time I’ve seen such a redundant configuration for solenoid valves; I’d appreciate it if experts could tell me in what situations this is used. Thank you!
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The second situation is more common in general; I really haven’t seen the first situation before Has anyone seen it? Thank you
Dual protection or a redundant approach with dual circuits
Series and parallel; our unit uses the second method for polypropylene
1 Applicable to: The consequences of rejecting chaining are more severe. 2 Applies to: the consequences of incorrect interlocking are more severe.
The second method is series connection; this may require a high level of control, or it can be used as SIL1 for interlocking the operation of one solenoid valve (the solenoid valve remains open under interlocked conditions, while it closes otherwise), with another solenoid valve being used for normal on/off operations. Batch operations can use this type
The second method is series connection; this may require a high level of control, or it can be used as SIL1 for interlocking the operation of one solenoid valve (the solenoid valve remains open under interlocked conditions, while it closes otherwise), with another solenoid valve being used for normal on/off operations. Batch operations can use this type
I mainly want to know in what situations or devices is the first type used? Because the interlock cut-off valves in the hydrocracking units I have worked with all use the second type
Series operation is generally not used in control valves these days. Series on-off valves of SIL1 grade are employed in process-controlled systems in the fine chemicals, pharmaceuticals, and polymer industries, where one solenoid valve serves as the control element while another acts as an interlock device. However, in many new installations, the SIS valves and DCS systems are designed to be separate from each other, so this approach is becoming less common in the future.
Only a very small number of circuits in hydrogenation units use a series configuration.