Can you comment on which of your pumps would support continous-on operation overnight without overheating?

When I do vaccum bagging, I frequently get pinhole leaks from connectors etc which are difficult to debug. My parts are mostly long tubes of special shapes. All reagents come from you, except that, as a bag,  I use thick long polypropylene sleeves which I connect with your red standard disk-connector, and seal both ends with a hot wire. The leaks appear to be around the connector, and are hard to debug. So  I just set my oil-free pump on continous pumping. It has a feedback, so it switches on/off every 3 seconds to retain the vacuum, which causes overheating, and requires me to set-up a separate cooling fan. I am now considering to get a separate pump, and I am wondering how it would behave if left on cotinously for 12-16 hrs at a time.

it really depends on the amount of leakage you've got, if a pump is fit for continuous operation. for very small leaks, a cheap rotary vane pump can handle continuous running, but if there is to much leakage, the oil will run out after a while, and the pump will fail.
so you really want to get your bag tight. I don't know exactly what type of sleeves you are using there, but most plastic films are not suitable for vacuum applications. maybe you could use a bagging film, and make a tube out of it with tacky tape. or you are using the through bag connector not carefully enough. maybe try a simple hose-through-tacky-tape method? either at the mold flange, or through bag.

I would agree that finding the leaks is the better solution than running the pump all the time.  It should be possible to get a leak free through bag connection.  Make sure there are no creases or folds of fabric trapped by the connector.  Ensure the rubber seal is in good condition and correctly seated.  Also ensure any connectors attached to it are properly sealed with correctly applied PTFE thread sealing tape.


Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

if every fold is a potential leak, I would rather do 3m tacky sealing, and never buy that film again? what is your diameter? there are professional 3 layer bagging tubes, in many different diameters.

I am having a hard time working with Gum Tape (which is the same as tacky tape, I assume ) and Vacuum Bagging Film. No matter how much I try, there always are creases in the area of that Vacuum Bagging Film that has contact to the Gum Tape. Do you guys have some tips?

Keep practising, you'll get there.

It shouldn't matter too much if the bag creases, you can stretch it out and seal the crease. Don't be afraid to push and pull the bag on the sealant tape quite firmly, it will stretch quite happily. 

Thanks Hanaldo.
I also came accross a tip of yours in another thread, which was to slightly heat up Gum Tape before using it.

I have experimented using a heat sealer, but with mixed results. It is hard finding the optimal combination of sealing duration and sealing temperature. I suspect VB160 Vacuum Bagging Film is not that easy to seal as it consists of multiple layers. Additionally Nylon absorbs relatively high amounts of water, compared to other plastics; this water could maybe interfere with the sealing process.
I googled around a bit and not many seem to be using heat sealers for vacuum bags, but there are some. On paper it seems like a good idea, as the potential for time saving is huge, compared to the usage of tacky tape.

Has anyone else expermented with a heat sealer?