Vacuum Gauge Precision (can't pull full vacuum)

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Vacuum Gauge Precision (can't pull full vacuum)

Author	Message
H4RTM4N	H4RTM4N posted 11 Years Ago HOT Topic Details
Group: Forum Members Posts: 7, Visits: 203	Hi all, My name is Andreu and I'm new to this forum. I've just received my order from EC and I'm already trying to make my own carbon fibre parts using resin infusion. For the first trial I wasn't concerned about the final quality of the part (a simple plate) as I only wanted to be familiar with the process. However, I noticed I couldn't reach 'full' vacuum. Instead, the vacuum gauge was stuck at -29Hg (0.98+ bar). I closed all the leaks in the vacuum bag but I kept having that remaining pressure inside. In order to be sure of that, I connected the vacuum pump to the resin catch-pot only. The hose that usually comes from the resin catch-pot was clamped so the vacuum was only made inside the catch-pot. When I pulled vacuum from the pot, I obtained the same result. Taking into account that I live in Barcelona and my house is <100m above sea level, I wonder if my equipment is all right or not. In other words, I want to know if the the vacuum gauge is simply not representing the reality inside the bag because of its precision. I can imagine 2 possible answers to the question: - YES, the equipment is just fine. The precision of the vacuum gauge of the resin catch-pot is somewhat near to 2mbar and that is why I obtain these 0.98bar. - NO, there's something wrong. You should obtain -1bar (-30Hg), which in reality represents the advertised 99.995% vacuum. Could you please help my clarify this issue? Thank you a lot and good luck to everyone! Regards, Andreu Tags catch-pot full vacuum precision vacuum gauge Edited 11 Years Ago by H4RTM4N
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fgayford	fgayford posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 433, Visits: 1.2K	As I understand it, Your at full vacuum at 29.9 HG so 29 is great! You could suck a cat inside out with that kind of vacuum. Fred
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H4RTM4N	H4RTM4N posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 7, Visits: 203	Well but it's still far from the 99.995% vacuum advertised with the small vacuum pump (which means an absolute pressure of around 0.2mbar inside the bag). As of now, there is way more.
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Matthieu Libeert	Matthieu Libeert posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 955, Visits: 3.4K	fgayford (19/07/2013) As I understand it, Your at full vacuum at 29.9 HG so 29 is great! You could suck a cat inside out with that kind of vacuum. Fred I just had to add this video after seeing your comment fred OT: I think 99.995% is in optimal conditions and so on... it's a number that is very hard to reach... 99% is 98% is allready more than enough for most applications Matthieu Libeert Founder MAT2 Composites X Sports website: www.mat2composites.com
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Warren (Staff)	Warren (Staff) posted 11 Years Ago HOT Post Details
Group: Administrators Posts: 2.5K, Visits: 7.9K	They are not the most accurate guages on the market but they are very cheap and accurate enough for most purposes. Its the change in pump tone that is a more relevant indicator for resin infusion processes anyway. A high quality oil filled calibrated guage would cost several times as much and be beneficial to very very few customers in reality. Warren Penalver Easy Composites / Carbon Mods - Technical Support Assistant
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H4RTM4N	H4RTM4N posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 7, Visits: 203	Thanks for the feedback people!
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fgayford	fgayford posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 433, Visits: 1.2K	matthieutje65 (19/07/2013) fgayford (19/07/2013) As I understand it, Your at full vacuum at 29.9 HG so 29 is great! You could suck a cat inside out with that kind of vacuum. Fred I just had to add this video after seeing your comment fred OT: I think 99.995% is in optimal conditions and so on... it's a number that is very hard to reach... 99% is 98% is allready more than enough for most applications Matt That video is hilarious! What is that cat thinking, had tears in my eyes its so funny. Fred
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fgayford	fgayford posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 433, Visits: 1.2K	H4RTM4N (19/07/2013) Well but it's still far from the 99.995% vacuum advertised with the small vacuum pump (which means an absolute pressure of around 0.2mbar inside the bag). As of now, there is way more. Throw out your cheap guage and buy a liquid filled professional guage and I am sure you will reach full vac. I know because I had the same disapointment your having. The dealer came out and put his mega expensive guage on and it reached full vac instantly. Fred
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prairiecustomcomposites	prairiecustomcomposites posted 11 Years Ago HOT Post Details
Group: Forum Members Posts: 26, Visits: 722	Fred, what brand of gauges do you recommend? And where do you purchase them? I have a feeling I am experiencing the same issue with cheap gauges Also, what makes a liquid filled gauge better or more accurate than a non-liquid filled gauge? -Mike-
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Warren (Staff)	Warren (Staff) posted 11 Years Ago HOT Post Details
Group: Administrators Posts: 2.5K, Visits: 7.9K	I think people are missing the point. Unless you are struggling to hear the tone change on the pump, then you dont really need a massively accurate gauge as the tone change will tell you when you have reached full vac and have no leaks. Warren Penalver Easy Composites / Carbon Mods - Technical Support Assistant
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