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Step 4Testing.
For testing I made a 'T' fitting out of 1/4 inch I.D. plastic pipe and hot glue. The 'T' fitting was connected to the vacuum gauge and the other plastic tubing by 3/8 inch vinyl tubing pieces I had laying around.
It worked pretty good and held the air, but I can see it is not that strong for everyday use, and will be replaced with proper fittings when I get around to it.
Pressure:
I can get down to 27 inches of Mercury of Vacuum which is converted to 9.668 T/square metre. The pump can also hold this vacuum pretty good when switched off. I lost about 2 inches of Mercury in one hour. The pump also had no trouble starting with 25 inches of mercury vacuum on the line working against it. I am pleased.
Plenty of pressure for anything I will be doing. Maybe too much for some projects. There is a pressure switch I am looking at building that can regulate this. It uses a vacuum valve from a car and a power switch. It looks about the best for fine adjustments to the line vacuum output.
The problem I see at this point is the CFM is very low. I am not sure the exact amount but estimates are 1.5 CFM. This is where I think if I can remove the chocking line in the discharge path that the vacuum CFM may be increased.
Another option is a reservoir. This could be installed in parallel with the pump and used to make an initial large evacuation then the pump could take the chamber down to a final vacuum pressure if desired.
This is a rough finish with many things left to be done, but from here anyone should be able to modify the system to their personal needs and shop area. Hope it works out and happy vacing.
It worked pretty good and held the air, but I can see it is not that strong for everyday use, and will be replaced with proper fittings when I get around to it.
Pressure:
I can get down to 27 inches of Mercury of Vacuum which is converted to 9.668 T/square metre. The pump can also hold this vacuum pretty good when switched off. I lost about 2 inches of Mercury in one hour. The pump also had no trouble starting with 25 inches of mercury vacuum on the line working against it. I am pleased.
Plenty of pressure for anything I will be doing. Maybe too much for some projects. There is a pressure switch I am looking at building that can regulate this. It uses a vacuum valve from a car and a power switch. It looks about the best for fine adjustments to the line vacuum output.
The problem I see at this point is the CFM is very low. I am not sure the exact amount but estimates are 1.5 CFM. This is where I think if I can remove the chocking line in the discharge path that the vacuum CFM may be increased.
Another option is a reservoir. This could be installed in parallel with the pump and used to make an initial large evacuation then the pump could take the chamber down to a final vacuum pressure if desired.
This is a rough finish with many things left to be done, but from here anyone should be able to modify the system to their personal needs and shop area. Hope it works out and happy vacing.
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I use a similar setup for vacuum bagging carbon regularly. To get the bulk of the air out I use a standard shop-vac. Pulls the mass of the air out in seconds.
As a reservoir, I use an old fire extinguisher. By adding two T-valves you can hook up both ends of the compressor to it and switch between pump and vacuum. Put the manometer and vacuumeter on the input of the valve otherwise you will pull a vacuum on the manometer, which will ruin it.
When using as a pump, add a filter to the vacuum side to prevent dust from entering. Dust will kill the pump very fast.
Use a mechanical timer to switch it on and off every 15 minutes. If you pulled a full vacuum and the system is otherwise sealed, this is enough to maintain the vacuum without over-heating.
Cheers