Identification Letters for Photo Eye

[shaunjones]

We are installing several photo eyes on a conveyor system to detect if there is a package backup on the conveyor. In the past I have used YS as the indentification for this (event, state, presence), but on this particular project some other ideas are being passed around (ZS). What ISA identification letters have people used in the past, and what was the reasoning behind using those?

Thanks,
Shaun

 

[JLSeagull]

Y is for event, state or presence. Z is position, dimension. Typicically for on/off valves with position switches to verify open or closed the switches are tagged ZS. Check your P&ID legend to see how Y is used. I don't normally see Y used in continuous fluid processes. However perhaps it makes sense for event in an automated conveyor system for some status indications.

 

[xnuke]

ISA 5.1 shows an example of a photoeye with a conveyor in section 6.8. They use QX for the light emitter and QS for the receiver.

xnuke
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