Blowing-down sight glass

Fizz

WM-SGO3, from 80's, with dirty sight glass half-way. Want to loosen petcock to blow-down, but not sure what to loosen. There's a nut similar to my 2000 SGo-6, on bottom of assembly, but also a detailed-like attachment on nut-do I turn nut, or other attachment?

nicholas bonham-carter

If you want to drain the sight glass regularly, replace the pet clock with a quarter turn ball valve, and some piping to accommodate a bucket to catch the dribbles.
My experience with those petcocks has been: once open-never close!—NBC

Dan_NJ

Something like this might work? I was surprised to find non-brass friction washers in my sight glass assembly too, since replaced, and this setup with ball valve now in place and working well:

https://www.youtube.com/watch?v=_z8v1YOQcM4

KC_Jones

nicholas bonham-carter said:

If you want to drain the sight glass regularly, replace the pet clock with a quarter turn ball valve, and some piping to accommodate a bucket to catch the dribbles.
My experience with those petcocks has been: once open-never close!—NBC

This 1000 times. I did this after seeing @Steamhead and @Gordo doing it on their installs.

Makes it super easy to keep it clean.

Gordo

Here is a quick video of a sight glass blowdown valve in action.
https://www.youtube.com/watch?v=PWaHRD-6bmQ

Fizz

Excellent advice, thanks guys!