Chamber Sealer Question

4Runner

I have a VP-215 and love it.  Here is my question.  Every now and then when the unit is vacuuming the bag will expand.  It always ends up like normal once the pressure is equalized and the seal is made but I'm just wondering what is causing this? 99% of the time the bag never changes until the equalization stage.  I haven't been able to tell what I'm doing to cause the bag expansion.  If anyone has an idea please let me know.  I'm just curious.   Thanks  

Canugghead

I notice that with my vp215 too but never looked deeper into it until now... just googled and found this useful info at https://www.chefsteps.com/activities/how-chamber-style-vacuum-sealers-work

Loading the Chamber Sealer

• Once the food is packaged, it’s placed into the chamber-sealer. The open end of all the bags should go over the sealing bar, and then be tucked back down into the chamber. Double-check that the edge of the bag does NOT protrude from the chamber, and then close the lid firmly to engage the vacuum pump and start the sealing cycle.

• If the bag sticks out of the chamber during the sealing cycle, there is no way for air inside the bag to escape as the surrounding pressure is lowered. As a result, the bag will appear to swell as the pressure inside the bag becomes much greater than within the chamber. If this difference becomes large enough the bag will burst, which can be messy.

Why the Bags Puff

• Because air rushes out of the chamber more quickly than it escapes the bag, the pressure will at first be slightly higher in the bag than the surrounding chamber, which will cause it to puff up inside the chamber. Although the bags puffing up is normal, this effect can cause the ends of the bag to slide off the sealing bars, which will prevent the package from being sealed at the end of the cycle.

Eureka! I never extend the open end outside the chamber, BUT occasionally the bag is too full and the open end does not extend over the sealing bar - this is as bad as exposing the open end outside the chamber because the open end is compressed between the sealing bar and the silicone strip above it... when that happens the bag over puffs and sometimes fail to seal.

Thanks for asking, learned something new! 

4Runner

Thx @Canugghead  I thought you might respond  

sctdg

I have VP-120 and according to the tech at Vacmaster if bag does that machine is defective . Had to send mine back for a exchange . Check your seal bar when bag blows up and see if bar has risen up before it should,that is what mine was doing .

Canugghead

Thanks for the heads up. I hope that's not the case with my vp215, since it happens infrequently and usually when the bag is too full. My unit is out of warranty anyway so I'll have to live with the issue until it becomes intolerable ;((

Canugghead

Just sealed a bag of leftover 'liquid' gravy and three bags of blanched flat beans. Came out just fine with about 1/3" of open end over the sealing bar.

Looking back at occasions when I ran into problem ... when sealing liquid I would instinctively move the bag as far from the sealing bar as possible (Foodsaver habit) to the point that sometimes the open end did not protrude over the sealing bar; so my precaution actually backfired, duh! Can't thank @4Runner enough for this thread!

4Runner

After reading the responses again...I'm thinking when mine has done it, I have the end of my bag last sealing bar and then have it punched down towards the bottom of chamber so it doesn't stick out of lid.  I wonder if this has anything to do with it.  It has been months since I have seen it though.  I may call VacMaster and see what they say.  Will report back ASAP.  

Canugghead

Perhaps the bag end was interfering with the sealing bar's movement?

4Runner

@Canugghead - I'm able to recreate the bag expansion deal.  Yes, it is when I slide the end of the bag down toward the bottom of the unit after crossing the sealing bar.  Not sure why exactly but it is pretty consistent.   I just won't do that anymore.  

Canugghead

Great to hear, thanks for sharing this learning experience. I'm now thinking perhaps the excess bag end got pushed against the front inner vertical side, thereby trapping the air in the bag that eventually ballooned?