Color of the interlock valve switch in SIS
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I installed SIS interlock valves, one of which is shown in Figure HV10805. During normal operation, the interlock valve is in the open state, and the color of the rectangular block in the image is gray. Does the color of the rectangular block turn red when the interlock valve is closed? Also, does the color of the two triangular shapes below change when the valve is closed? Please share your thoughts; it counts as extra points.
Logically speaking, the two green triangles below should not change color; it is the rectangle above that can change color, usually turning red when closed and green when open. The gray color in your case is, logically, due to the absence of a valve position signal. I’m not sure how you managed to set the valve’s open state to gray. Check the IO status – is there any signal?
It mainly depends on how you configure the SIS; everything you mentioned can be achieved through instrument configuration. Some use the squares above to indicate the transformation, while others use changes in the color of the valve body to show it
The color changes for the valve position below are appropriate: green for open and red for closed. This signal comes from the on-site valve position limit switch. This valve should have a solenoid valve! If there is a solenoid valve, it is more intuitive to draw a symbol for the solenoid valve next to the symbol of the valve cylinder; it would be best if the color change of the solenoid valve corresponded to its DO signal As for the color change of the cylinder, it doesn’t matter; it can change color along with the valve, or it can remain unchanged. Of course, all symbols and color changes should be consistent throughout the entire project or device. You can take a look at how other similar valves are depicted; perhaps this valve doesn’t have a limit switch, or maybe the configuration engineer missed it!
Let’s talk about the standard practices for our SIS valves: 1. The color of the square is green when the valve is fully open, red when it is fully closed, and yellow flashing indicates a valve fault (gray should be the color indicating a confirmed fault, meaning the valve is not fully open or closed)； 2. The color of the two triangles is green-DO set to 1; the solenoid valve for the valve’s air supply is activated, air flows into the valve’s cylinder, and the valve opens ； Set to 0 for red-DO; the solenoid loses power, the cylinder releases air, and the valve closes ； 3. The SIS interlock valve is selected in accordance with the fail-safe principle: it remains open during normal operation and closes when interlocked; it is a single-acting FC pneumatic on-off valve.
The general approach is to use the feet to guide the head.
Regarding the discoloration of SIS valves: 1. Discoloration in the actuator section indicates that the solenoid valve is powered or de-energized； 2. The color change of the valve body indicates the actual on/off state of the valve ； 3. As for the specific color changes before and after, they are defined in the FDS functional design specification ； 4. If this valve is configured in the SIS and displayed on the DCS screen, communication is required.
It depends on how you set it up. Generally, a rectangle is used to indicate the valve position: green means open, red means closed, and gray indicates that the valve is not fully open or not fully closed. The triangle represents the output value at point DO: 1 means green and 0 means red
There are various ways to set this up. At my previous company, the valves were connected to DO signals; when the value was 1, it turned green, and when it was 0, it turned red (or gray, but usually red). For that feedback indicator, it turned green when feedback was received, and red when no feedback was received. If feedback was received both when the device was on and when it was off, or if no feedback was received at all, it might turn yellow (or gray, but usually yellow)
It depends on how your DCS system defines it; usually, the actual valve has already moved, but the signal indicating whether the valve is open or closed doesn’t arrive back, or in other words, there’s a feedback error, and such a situation is classified as gray. Normal feedback should be indicated by red for closed status and green for open status
It should normally be red-green; is gray the intermediate state?