Hi,
I'm learning infusion and trying to get all the setup with minimal leaks. I'm using EC4 (i've fitted it with ball valve, vacuum gauge and air inlet valve), CP1 catch pot, Greisinger GDH 200-14 gauge at the very end. When pulling vacuum GDH 200-14 starts from 1012 mbar and drops to -2 mbar. Pump side gauge shows -1 bar, catch pot gauge shows -0.95 bar.
Questions.
1. I understand that gauges put closer/further from pump will show different values. Should I worry about GDH 200-14 showing -2 or it's just an measurement error I should ignore?
2. After pulling vacuum and clamping hose between pump and catch pot GDH 200-14 shows this:
@ 0 min -2 mbar
@ 5 min 34 mbar
@ 10 min 37 mbar
@ 15 min 38 mbar
@ 30 min 42 mbar
What is acceptable leak rate ?

Thats a massive leak rate. With a GDH-200, I won't infuse until I am at about a 3mbar drop over half an hour.

You can largely ignore the actual value and just look at the drop. The value will change based on location, hose length, weather, etc. Obviously if you know you normally get down to below 10mbar and you aren't getting below 50mbar then you've likely got an issue, but the drop rate is more important. If the value won't go below 20mbar but it holds 20mbar pretty rock solid (mine will often flick between two values, like 20/21/20/21 etc. but never actually changes) then you can ignore the value and you are good to go. If your value is going down to 2mbar but dropping to 30mbar in 5 minutes then you have a pretty substantial leak.


If the gauge value seems to be dropping but I can't find any leaks, I actually also try clamping the Greisinger off and perform a static drop test as well, just in case it is a connection to the gauge that is the issue. This has been the case once or twice, so it is worth checking before scrapping the job and starting over.

Thank you Hanaldo! Will try clamping off different sections and looking for leak.

It really depends on the part and the tooling - leaks are bad - but some are worse than others.  The thing that stands out to me is that the bag drops super fast initially and then the rate of "leak" goes way down after 5 minutes.  How big is the part and what quantity of fiber / core?  You may have a moisture / volatile problem especially if it is warm where you're working.  Usually a real leak will just keep leaking at a pretty steady rate.  You probably have a leak too - everybody has leaks - but not a huge one if you can get down to 0mbar (or -2).  Try leaving the part under the bag for an hour or two to boil off moisture - and then doing the drop test.  You may find it gets better.

That’s a interesting leak rate. What I can see from your leak rate is moisture in your setup. Below 20mbar the water starts to vaporize and that lets the pressure drop dramatic at the beginning. After 5 min your leak rate is perfect.
I allow 1mbar/min. Usually that’s the leak rate where it stops to cause problems.
You should evacuate longer to get all moisture out, you will see that you won’t have that initial pressure increase then and your vacuum will be stable.