P&ID Symbols?

Hi every one
This is a screen shot from P&ID for water treatment plant:


What is meant by symbols 1 and 2 because they are not found in the legend?

mosama said:

Hi every one
This is a screen shot from P&ID for water treatment plant:

What is meant by symbols 1 and 2 because they are not found in the legend?

Click to expand...

Hello mosama;
Your screenshot seems to be missing from your post.
Regards,
Daniel Chartier

dchartier said:

Hello mosama;
Your screenshot seems to be missing from your post.
Regards,
Daniel Chartier

Click to expand...

I can see it. But no help with the symbols though.

I think #1 is an air trap, and I suspect #2 are pressure gauges, although pressure gauges normally have arrows and not circles at the ends of their lines. They are most likely gauges of some type.

#2 looks more like a float switch or a float activated valve to me, something like a water closet fill valve.

Keith

Based on the apparent function, eg, a sand and gravel filter, my guess is that symbol 2 refers to a screen or diffuser, although it is not a symbol that I am familiar with. My completely wild @$$ guess is that the circle represents a housing and the slash with the circle on the end represents a screen in the housing, possibly a serviceable screen.

In a normal sand and gravel filter water would flow into the vessel and out the top diffuser, through the filter media (sand/gravel), and then exit the vessel through the lower diffuser. To backflush the filter, fluid flow is reversed; the fluid enters the vessel and flows out the lower diffuser, then up through the sand media, lifting debris from the media, and carrying it out the top of the vessel and down the drain.

I have no idea what #1 is - but sand and gravel filters often have a differential pressure switch or sensor to determine when to backflush the filter.

Thanks for every one help