ESD level switch tapping point (with respect to bottom of vessel) 1

[3ooody]

while looking up in the P&IDs of our plant I came across some separators & Scrubbers that didn't mention the dimention of the ESD level switch tapping point, where on the other hand some other vessels had this information (for example: LSLL set @ 1200 mm -with respect to bottom of vessel), so I'm trying to modify these P&IDs by collecting the right information to submit to our design department, my questions are:

1- should I go for the vessel's data sheets and look up the specifications of these vessels to find out the tapping point dimentions?

2-or take the measurements my self? (if yes) what is the proffesional way/device to take measurements for a specific tapping point on a vessel (with respect to its bottom)?

thanks

 

[Weegie]

I'd take a look at the vessel vendor drawings. your mechanical engineer/department will have specified a centreline elevation of the flange/tap connection for the switch/device. If the vessel is already in service, check with the plant operators and ask what the ESD level is set on the plant control system. (The operator reference may be relative to fill percent of the vessel i.e LSLL set at 20% full) If all else fails, take the vessel vendor drawing and go to the vessel itself. Confirm the elevations of some other flanges/tap points on the drawing against the actual vessel itself and measure from there to your centreline point.

 

[3ooody]

The control setpoint (which is the level percentage) won't do me any good because it's not accepted -standard wise- as a refference to be added in the P&ID details, the vendor drawings is a good suggestion, I guess I'll do that, thanks weegie.