Extra edition, extra edition! Everyone in the instrumentation field, come and take a look. . . .
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What does that control valve at the bottom of the diagram mean? What do HV, HY, and HIC stand for respectively? {:1_90:}{:1_90:}
Why is a DN20 valve used at the base of the instrument? Isn’t that troublesome to use?
Key points of the answer? You didn’t answer any of my questions: dizzy:
A look at HG_T20505-2014 \"Functional Indicators and Graphic Symbols for Process Measurement and Control Instruments\" will make it clear.
The HV6003 manual control valve (without PID control), the solenoid valve for the HY6003 manual control valve, and the HIC6003 manual control valve enable adjustment and control from the control room.
HV6003: Control valve position indicator (non-PID control); HY6003: Electrical valve positioner on the control valve (the I/P in the upper right corner indicates current/pneumatic pressure conversion); HIC6003: Manual control and indication in the control room via DCS.
H: Hand V: Valve Y: Auxiliary devices I: Indicate C: Control
Although he didn’t answer your question, it’s such a basic question – why didn’t you check it yourself first? Sometimes HY may also be omitted. Actually, what he said makes more sense; it’s such a waste.