First time pressure canning, using a 23qt Presto pressure canner. Followed the instructions, vented for 10 min before adding the weight and it built up pressure no problem. I noticed the over pressure plug was slightly sticking up, but nothing was coming out of it. I watched the canner the entire time and it never went above the recommended 10lb for my recipe. Is this normal or could something be off?
Thanks!
by _jethro
5 Comments
Hi u/_jethro,
For accessibility, please reply to this comment with a transcription of the screenshot or alt text describing the image you’ve posted. Thank you!
*I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/Canning) if you have any questions or concerns.*
If you didn’t see any leakage around the overpressure plug, it probably wasn’t the problem. Was the weight rocking at all? And was your dial gauge tested before you first used it?
Is this the black rubber-like plug that’s a tight fit or the silver one that moves freely? If it’s the black one, just make sure it’s completely seated each time you use the canner. It’s designed to completely blow out if your canner ever builds up too much pressure. That way pressure is released through the hole. If it’s the silver plug, as pressure builds it’ll pop up (like a turkey timer but not as dramatically). When it’s popped up, it engages a safety mechanism that’ll keep you from opening the lid while there’s pressure.
The black ones will need to be replaced now and then just like the gasket.
It is normal for the black rubber “blow” plug to rise up a bit like that. It just means the canner is under pressure. It would take a much stronger pressure buildup to actually blow the plug out. That is what keeps your pressure canner from exploding if the metal weight vent gets plugged by debris. 🙏🏻🦋
The plug is made of rubber and is flexible, the only reason its there is because if the vent port (the part you stick the weight/regulator on) becomes plugged this rubber plug will blow off rather than allowing the canner to explode catastrophically. It is a safety fuse (or fuse plug if you wish). It should not be leaking, weeping, venting steam when the canner is operated between 0-15 PSI but because it is flexible (also removable when you wish to do boiling water processing) may bend or deflect.
Over time and use the rubber can harden so that it begins to leak or crumble (making it useless in every regard), Presto sells gasket and plug sets as a pair, if one is worn out it’s probably worth to change the other.
The regulator your Presto has is set to vent at pressures above 15 PSI and will only move when that happens and really there is no reason you need to be operating it that high.
The presto adjustable weight is a nice tool to add, it regulates the pressure (though you still have to adjust heat input) to either 5, 10 or 15 PSI. It makes a nice addition to your kit and it is the regulator that sort of dances about when its operating (and regulating) pressure; you really do not want to see your 15PSI weight doing that dance, you would be wasting energy needlessing boiling off the water in the canner (which could lead to it running dry).