I closed 3 bays down last week using air blowdown and Washer Fluid in the HP hoses...In the past I also blew out the WF as the last step....The only issues I had was debris would often clog a tip when reopening...Changing from galvanized wands to SS helped with that...But this time I tried something even a little different. Instead of blowing out the washer fluid, I left it in the HP hose...I think allowing air inside the hose and leaving it that way for a few days isn't good...
Opening all 3 bays below freezing was easy....Turn the breakers back on, open the weep ball valves to each bay, then blowing the WF out with HP rinse...Just took a few minutes to open the bays back up. At minimum, I always leave 1 bay open...Even down below zero....I have had people wash down to -5°....They did say they were driving home a short distance and putting their vehicle in a heated garage!
Since I work a full time job like most SS operators, keeping at least 1 bay open during extreme cold is easiest for me while saving on weep water/sewage costs. If it warms up through the day, at least I can keep 1 or 2 bays open till I get home...Then open the rest if the temps permit.
For those of you that want to incorporate a semi-automated air and washer fluid blowdown for your HP lines....Heres what I did...Air and WF come in from the bottom left...The Washerfluid hose is connected to the washerfluid
flojet that winterizes all my LP hoses...The ball valves take care of the rest. Shutting a bay down only takes a few minutes.
Kevin, to answer your question, I don't think air alone will work. Even after blowing down the HP hose with air, I still get a little water come out when I pump in WF....So for me, blowing out with air alone would be a huge mistake!