On Wednesday, December 12, 2018 at 1:53:18 PM UTC+2, Pete wrote:
Hey all,
I have noticed some gliders have what look like small fuel filters spliced into the tubing prior to avionics. I imagine this is a safeguard to dust, etc entering the avionics. Seems to make sense eventually what's outside is going to get inside....

However, is this necessary? I see a lot of old gliders without them. No mention of it in the manuals.

I'm redoing my panel with new avionics. Before I install I would like RAS's opinion if some sort of air filtering to my $2,000 variometer or shiny new ASI is good practice?
Thanks!

The filters cost nothing and stop water droplets or dust entering your instruments. All gliders I've seen (new and old) have filters on all pitot-static tubes. Hard to imagine any reason to not install them. The water enters easily trough fuselage static ports, too.