DCS, SIS systems
Thread Content
As shown in the figure, the shut-off valve is interlocked with the monitoring instrument; it opens when the oxygen content is too high. So, when the oxygen level in the system is not too high but the pressure in the upstream system is too high, I need to relieve pressure through the shut-off valve. Can this shut-off valve be manually opened from the DCS? Seeking help from experts! ! !
This post was last edited by bfdlwolf on 2018-12-29 09:06; entering the SIS system is not shown in the image. A soft switch can be set up in the DCS, and through this soft switch, the valve can be manually opened on the DCS.
By examining the logical relationships in the diagrams, it’s not an SIS interlock system; in the case of a DCS interlock, the valves that need to be controlled can be operated via the DCS. Therefore, it is possible to use this valve to relieve pressure
It seems that this can be achieved following normal logic. Please double-check that again.
The operation of solenoid valves is achieved through relay signals; whether it is the output from an oxygen content analyzer or the input to a solenoid valve, control can be implemented.
It can be opened manually. Just create two HS-O and HS-C on the DCS screen. Or you can directly apply a 2oo1 logic to the pressure signal and the oxygen level signal in order to open the shut-off valve.
It should be possible to release pressure manually; you’d better ask the process team or the design institute
The affirmative form is possible; any logical protection has the function of enabling and disabling. Machines are not completely reliable, so manual control is the last resort. For this, you can develop another logic: if it is not used frequently, you can disable this protective interlock, manually open the valve, close it once the pressure returns to normal, and then re-enable the interlock protection.