Let’s take a look and see if there are any issues with the design in the picture Those who have done it can give a description. Haha, let’s learn together*!

This post was last edited by ssln123 on 2018-3-3 at 11:50. 1. Electrical signal lines should be represented with dashed lines. 2. For those signals related to level interlocks, an operator is needed before they reach the actuator, such as a 2-to-1 selector or a high/low selector; otherwise, the logic will appear chaotic. 3. In tank areas that represent major hazard sources, SIS should be used for interlocks, rather than DCS. 4 The on-site pressure and the remote-pressure signals should be sourced from separate sources. 5 The naming of the control valves and isolation valves is incorrect, and the legend for the control valves is also wrong. 6 The DCS symbols for flowmeters are not drawn directly on the pipelines in this way

This is what XXX Design Institute provided :)

I agree with the suggestions you made: 1. Dashed lines should be used. 2. Yes, for example, H signal is used for alarm purposes, while HH signal is used for sequential actions. 3. It’s mainly a solvent; it’s not clear whether it qualifies as a highly hazardous substance. The design institute designs it based on DCS principles. 4. Right, two pressure gauges should be installed at the pump outlet. 5. There are no control valves shown in the diagram; only the one for supplying nitrogen gas, N1, is a self-acting control valve. 6. Yes, a flow meter should also be included in the diagram. The logic presented in the diagram is a bit confusing. Do you have any similar application examples that you could share? My understanding is as follows for feeding: Start the pump and open valve 115-2; when the liquid level in tank V21111 is reported to be too high or the feeding fork switch indicates a low level, stop the pump and close the valve. For discharging: Open valve 108 and start the pump; after 5 seconds, open valve 115-1. Once the flow volume reaches a certain threshold, stop the pump and close both the inlet and outlet valves. Then open the return valve 107 and close it after a few seconds. Stop the pump and close the valves when the liquid level in the workshop tank is reported to be too high or the level in tank V21111 in the storage area is reported to be too low

What the heck is LAS-2117? Measure the liquid level in the pipeline? For more complex logical relationships, one should refer to the logical explanation or logic diagram provided by the design institute. Additionally: Regarding the naming of control valves and shut-off valves, different design institutes may have varying conventions; as long as it is specified in the main diagram, it will be possible to find a basis for it, and the same applies to the legends.

The tank does not seem to have a high liquid level alarm; the function of HV-21107 is unclear, and it appears to be unnecessary

Could I find a P&ID diagram produced by a large company to take a look at? It's okay to take a look at the legend as well.

That is a tuning fork level switch; it stops the feeding pump when there is no material left in the pipeline. Haha, the design institute didn’t provide a logic diagram; if I had one, I wouldn’t be here asking everyone for advice.:L

LAS2115-2 is a high tank level alarm, while LIAS21116 is also a tank level alarm. HV21107 is used to control backflow. When the pump is stopped and the valves are closed, the pump stops due to inertia and does not stop immediately, which causes the material to impact the outlet pipeline and results in significant vibration. Enabling backflow is equivalent to releasing pressure

I know some friends who work in systems and have experience with logic designs for tank farm control in this area; could they share some insights?