I got help from a young colleague and he was able to close enough leaks to get some pressure so I could find the rest of the leaks with the ultrasonic leak detector. It took me the whole Saturday to finish with an absolute pressure of 260mbar and a 100mbar pressure drop per minute. Very disappointing and it brought me to the end of my rope. Time for a good night rest and thinking about a plan of attack for the next day (Sunday) My goal remained to finish this infusion at the end of the weekend, it has to happen.
After a good night rest we went to the workshop together with my wife and son who will help me with their good ears to at first resolve the still remaining leaks and second to assist me with the infusion.
There are two suspicious spots. At first the bottom of the deck hatch, it looks like it is sort of porous. I cannot find the leak but can hear the flow of air. Now this is in the direct vicinity of the vacuum port and I decide to accept it this way. Second is the beam flange at the port side. It is the same area where I had problems with air leakage during the infusion of the hull bottom, despite my precautions I’ve taken in this area. It seems to be not enough so I decided to open the bag and to try to make some repairs with tacky tape. The air leakage is coming from inside but there it is not possible to locate where it comes from. After the bag has been closed – not an easy job – it appears that the repairs are not of much help and it seems like the air leak has moved. In a last attempt I opened the bag for the second time to paste a piece of vacuum film onto the beam flange. It is the last attempt, the vacuum bag would not survive a third time. Now there is a little improvement, but it is still leaking somewhere. I decided to accept it and inserted an infusion needle in a strategic position through the bag and into the peelply. I connected a vacuum tube to the syringe with the intention that this by-pass sucks the unwanted air directly so that this air cannot pass through the laminate.
With these two spots of air leakage a high vacuum level is not possible anymore. Normally in my infusions this is an absolute pressure of around 25 mbar. For the rest of the bag I am pretty sure I did all the possible things to get an airtight bag. However, there is still a 100mbar pressure drop and we cannot find the source of it. Very frustrating.
I decided to start the infusion and to use the the resin flow to detect the leakage. Well, after opening the valve, that was not necessary anymore. Immediately I saw a lot of air coming through the ballvalve into the resin tube. Thus the valve and/or the connection between valve and tube was the malefactor. A little bit of tacky tape around the valve and tube and the whole problem was resolved. Wow, what a stupid detection. This leakage was to big to be detected by the leak detector and I had forgotten to ask my wife to hear for leakage around the ballvalve.
From now on the rest of the infusion went flawlessly without any air and with an absolute pressure of only 115 mbar due to the other two harmless leaks. Quite a relief.
While the auxiliaries went home I kept control over the cure of the resin till it was sufficient gelled to leave it alone.
All in all, despite the bad start, and a small incident with a collapsing resin trap, it was again a successful infusion.
And I made a youtube film of this succesfull event. Enjoy 🙂