[Q&A Question 335] 2017.12.19
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【Q&A Question 335】December 19, 2017: What is the reason why \"air-operated valves\" are generally used for regulating the outlet temperature of a furnace? For safety reasons, in case the air supply to the valve is suddenly interrupted, air-operated valves are employed. These valves operate in a \"positive\" direction; therefore, the control mechanism also operates in a \"positive\" direction, and so does the transmitter. As a result, the control action must be in a \"negative\" direction in order to reduce the output when the furnace temperature rises, thereby closing the valve and lowering the furnace temperature. (Unless otherwise specified, all Q&A questions are based on hydrogenation units.) ) For management purposes, if you need to view content from a few days ago, please go through the summary post below. 2017 Q&A Summary Thread (updates starting now) https://bbs.hcbbs.com/thread-1657793-1-1.html 2017 Daily Question Summary Thread (updates starting now) https://bbs.hcbbs.com/thread-1657794-1-1.html 2017 Daily Image Summary Thread https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1875160 2017 LNG Version Daily Question List https://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1804162 2016 Q&A Summary Thread (updates completed) https://bbs.hcbbs.com/thread-1597792-1-1.html
For safety in the event of a sudden interruption of the air supply to the valve, a normally open valve is used. It operates in the “positive” direction; therefore, the control element also acts in the “positive” direction, and the transmitter functions in the “positive” direction as well. As a result, the control action must be in the “negative” direction in order to reduce the output when the furnace temperature rises, thereby closing the valve and lowering the furnace temperature.
For safety in the event of a sudden interruption of the air supply to the valve, a \"air-operated valve\" is used. It is a valve that operates in the forward direction, and both the control mechanism and the transmitter also function in this forward direction; therefore, the control action must be in the reverse direction in order to reduce the output signal when the furnace temperature rises, thereby closing the valve and lowering the furnace temperature.
For safety in the event of a sudden interruption of the valve air supply.
For safety in the event of a sudden interruption of the air supply to the valve, a normally open valve is used. It operates in the “positive” direction; therefore, the control element also acts in the “positive” direction, and the transmitter likewise operates in the “positive” direction. As a result, the control action must be in the “negative” direction in order to reduce the output when the furnace temperature rises, thereby closing the valve and lowering the furnace temperature.
For safety reasons, it can be automatically shut off in case of a failure! It operates in a positive manner, in line with normal human reasoning
For safety purposes, in the event of a sudden interruption of the air supply to the valve, air-operated valves are used. These valves operate in the “forward” direction; therefore, the control element also operates in the “forward” direction, and the transmitter as well. As a result, the control action must be in the “reverse” direction, so that when the furnace temperature rises, the output of the control system decreases, which in turn causes the valve to close and the furnace temperature to drop
For safety in the event of a sudden interruption of the air supply to the valve, a normally open valve is used. It operates in the “positive” direction; therefore, the control element also acts in the “positive” direction, and the transmitter functions in the “positive” direction as well. As a result, the control action must be in the “negative” direction in order to reduce the output when the furnace temperature rises, thereby closing the valve and lowering the furnace temperature.
For safety in the event of a sudden interruption of the air supply to the valve, air-operated valves are used. Since they operate in the forward direction, the control element also operates in the forward direction, and the transmitter does as well; therefore, the control action must be in the reverse direction so that, as the furnace temperature rises, the output of the control system decreases, which in turn causes the valve to close and the furnace temperature to drop.