Checking check valve spouts

[MarquisVII]

I had 95 taps on 4 lines this year and when I pulled them at the end of the season I had 4 or 5 that had a little wood chips stuck in them them that held the check valve open, causing lots of sap to squirt out everywhere upon pulling them. At various times throughout the season when fiddling with the manifold or doing other various maintenance near the pump, sap would rapidly shoot backwards in lines.

Would this still happen if none of the CVs were clogged?

Is it a best practice to pull all CVs a day or two into the season just to check for stuck wood chips? Because I did my best to tap and then NOT touch them at all unless there was an obvious leak, thinking that any unnecessary tampering will hurt yield.

Curious to hear tips and tricks.

[DrTimPerkins]

A failure of 4-5 spouts on 95 taps is about a 4-5% failure rate. That is not at all bad on a mechanical system, especially one that has been in place for multiple weeks. Regardless, you will see sap flowing back up the lines whenever you introduce air or lose vacuum. That doesn't necessarily mean that the CVs have failed. The air in the lines (between the sap slugs) is fairly elastic, so when there is vacuum the air gets "stretched out". Once your vacuum drops, the air will snap back, carrying liquid with it.

No, it is not good practice to pull spouts after they've been put in. You risk damaging the taphole and causing a leak. Better off just accepting a small failure rate in the system, but try to avoid it by using a good sharp tapping bit to reduce wood chips in the first place.

[maple flats]

While Dr Tim might tell me this is a poor practice, when I drill a tap hole, I break off a small stick from anything close by and clear the taphole, never blow in it to clear it out. I think doing that minimises the chance you will have debris in the hole to clog the CV. I used a new twig on every hole, there seems to most always be a dead twing nearby to break off to clean the hole. I also prefer tapping when the sap is flowing, to help push the debris out too, however when I had my most taps I was trying to be finished tapping before my 3 college students had to return to school, so the sap was often not flowing. As I got to have fewer taps, i did tend to tap during a warmer day and the sap was often flowing, sap flow will help push that debris out. I used CV spouts or CV adapters every season after the first year they were available, I don't think I ever had a 4%+ plugging issue, maybe a 1% max was about it.

[SeanD]

I do the same as Dave - though I'll reuse the twig until I lose it. Like he said, a good flow pushes anything in there out at least to the edge of the hole. The holes on the frozen sides of the tree need some sweeping out more often. I'll still sometimes see some bits work their way into to the tap and down the line on that first day. Try adding a valve just before your manifold so when you work on the pump you don't lose vac or sap.