Question: What does SHL mean?
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Seeing the symbol FFSHL, consulting the standards reveals that FF stands for flow ratio, while SHL refers to the high/low switch. I’m very confused and don’t know what this thing is used for. I earnestly ask experts for guidance; thank you very much. I work in pressure vessel design, so I know nothing about this; please don’t laugh at me.
If FF represents the flow ratio, then FFSHL represents the high and low limit alarms and interlocks for the flow ratio.
Could you be more specific? High/low limit alarms and interlocks? So it means that it will trigger an alarm whether the traffic ratio is high or low?
Reply to 2# ldym: Could you be more specific? Does it mean an alarm is triggered whether the traffic ratio is too high or too low? Where can one tell that it’s a chain?
This post was last edited by masanhong on 2010-5-27 10:16. In gauge symbols, it should mean this. Learn from each other!* No one should laugh at anyone else!
What about FFAHL? Isn’t this the one that indicates the low and high limit alarms?
Reply to 2# ldym: What about FFAHL? Isn’t this the one that indicates the low and high limit alarms? According to the table, S stands for switch and interlock, while SSHL stands for high and low switch. I’m too stupid, sorry
A for alarm, S for switch; an alarm requires some indication – otherwise how can it give an alarm? Whether the switch has interlocking features depends on the process requirements; perhaps the switch serves solely as an alarm function.