Issues regarding the control strategy for shutting down the pump via interlock based on low inlet pressure and high outlet pressure of the injection pump
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I would like to ask the experts: for the pump shutdown mechanism that is triggered by low pressure at the inlet and high pressure at the outlet of the injection pump, is it better to use electric contact pressure gauges for this purpose, or to use a PLC (RTU) to monitor the pressures at the inlet and outlet and then use the control system to shut down the pump? Which of these two methods is safer?
Personally, I think the first option is better; it should not be included in the calculations
We chose the first option; no accidents have occurred yet. The second option requires a higher investment
Either is fine; it’s a matter of precision error. For fine chemicals, the latter is used
The first method is simpler and more reliable, as the signal goes directly to the electrical control cabinet. For the second method, it first needs to go to the PLC, undergo logical processing, and then be sent to the electrical control cabinet. If the operator needs to monitor the pressure before and after the pump, then the latter can only be used.
If there is already a PLC system, you can ask the instrumentation and control team to implement interlocks. If no PLC is available, electrical contact pressure gauges can be used for interlocking, but it is necessary to ensure their reliability~~
Let me talk about what I did in the end. Since the PLC system is already in use and the pressures at the inlet and outlet of the water injection pump have been monitored, it is considered appropriate to use the PLC to shut down the pump in a controlled manner ； Later, since the owner considered electric contact pressure gauges to be more reliable, the final solution was to combine the PLC-driven pump shutdown signal with the signal from the electric contact pressure gauge in series, thereby providing a dual safety mechanism. What do you all think about this approach?