New ideas for controlling pneumatic control valves with controllers

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This post was last edited by john1628 on 2015-7-20 08:26. It’s just an idea that came to mind; I think it’s cost-effective, but I’m not sure if it will be practical. I hope everyone can give their feedback. Three XMT628PID instruments (4-20mA) are used to control three relays respectively; one signal – the signal sent by the pressure transmitter – is supplied to all three instruments to make them operate, thereby controlling the opening degree of the valve. (Note: The gas pressure ranges from 4 kilograms to 0 pressure.) Consider the following: 1) The first instrument is set to transmit a signal of 16mA; when a pressure signal is received (assuming it is 4 kilograms – 3 kilograms), the pneumatic butterfly valve opens to 10% of its full capacity, which triggers the relay to start timing, and after 10 seconds the valve closes ； 2) The second fastest gauge is set to transmit a signal of 13mA; when a pressure signal is received (assumed to be 3 kgf – 2 kgf), the pneumatic butterfly valve opens to 15% of its full opening, which triggers the relay to start timing, and the valve closes after 10 seconds ； 3) The third gauge is set to transmit a signal of 10mA; when a pressure signal is received (assumed to be 2 kgf per 1 kgf), the pneumatic butterfly valve opens to 20% of its full opening, which triggers the relay to start timing, and the valve closes after 10 seconds. Please leave more comments; this will help to control the valve opening degree.