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Old 12-05-2013, 02:07 AM   #1
a_double

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Default relative vs absolute pressure when infusing

Hi guys, i have a bought a few meters of MTI hose and i'm told for me to get the desired results i have to make sure my system is operating @ absolute pressure and that needs a digital gauge instead of the normal analog vacuum gauge so what i need to know is , is everyone using a digital gauge during their infusion process if not what are you using to ensure that you system is @ absolute pressure.

with my pump i can only reach a max 27Hg's and the pump is still brand new

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Old 12-05-2013, 05:49 AM   #2
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The gauge doesn't change your vacuum, another vacuumpump will. The only thing is, one gauge displays more accurate then another. What kind of vacuumpump do you have and how many meters are you below or above see level ?
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Old 12-05-2013, 06:31 AM   #3
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Quote:
Originally Posted by Michiel View Post
The gauge doesn't change your vacuum, another vacuumpump will. The only thing is, one gauge displays more accurate then another. What kind of vacuumpump do you have and how many meters are you below or above see level ?

Hi Michiel, currently where i'm based i'm 3280 feet (1000 meters) above sea level.
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Old 12-05-2013, 04:52 PM   #4
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Yes, a digital absolute pressure gauge is essential for vacuum infusing, and I highly recommend it. Vacmobiles sells a good one, thats what I use.
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Old 12-05-2013, 11:14 PM   #5
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Here is one as well:

http://www.vacuumsystemen.com/toebeh...1000-mbar.html

Which works OK, and can be used for logging as well.

Also the digital vacuum switch that I am working on displays the vacuum pressure digitally in 1 mbar increments, and probably turns out cheaper.
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Old 12-06-2013, 08:01 AM   #6
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Look for Greisinger GDH 200-14. It is one of the cheapest and used by many professionals. I like it and use it.
I just read your dry spot thread. Have you meassured the vacuum direct at the pump? Maybe you have pores in your mould and thats why you also can not get perfect vacuum. Have you made a drop test?
Post pictures from the mistake and your pump. We will fix your problem.
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Old 12-07-2013, 04:51 PM   #7
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Quote:
Originally Posted by a_double View Post
Hi Michiel, currently where i'm based i'm 3280 feet (1000 meters) above sea level.
Not quite sure why no one has mentioned this yet, but Vacuum is influenced by altitude. Max attainable Vacuum for 1000m is 28.9 inHg which is 96.6%.

Just so your aware of what is achievable where your located and the pump may be fine @ sea level!
Jim.
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Old 12-08-2013, 11:00 PM   #8
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Quote:
Originally Posted by DDCompound View Post
Look for Greisinger GDH 200-14. It is one of the cheapest and used by many professionals. I like it and use it.
I just read your dry spot thread. Have you meassured the vacuum direct at the pump? Maybe you have pores in your mould and thats why you also can not get perfect vacuum. Have you made a drop test?
Post pictures from the mistake and your pump. We will fix your problem.
Hi DDCompound, how can i fix pores on the mold? i'm in the process of buying Greisinger GDH 200-14 and i hope it will be a worthwhile investment cos this is not cheap .

i will send pics later today.
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Old 12-13-2013, 10:04 AM   #9
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I would like to know if it really is a necessary item, maybe to avoid surpassing the pressure of vapours of the resin ?? what is really its importance ? to avoid the mistakes induced by barometric pressure variations ??
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Old 12-13-2013, 10:27 AM   #10
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Your vacuum doesn't increase by a digital gauge. Its easier to monitor your vacuum but it isn't necessary. It does make the job easier.
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