Vacuum pumping CF bottles

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LMNOP

LMNOP

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Jul 7, 2021
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Southern United States
Hello,

How often do you vacuum pump your CF bottles to remove stale air and any unwanted residues and moisture?

I vacuum pump my CF bottle every two and a half months or every 7 and 3/4 fills to ensure the bottle is free of contaminates.

I have noticed that since doing so the accuracy has substantially improved across all shot counts. I use the air intake on my Yong Heng explictly for this purpose and have removed the brass sintered “muffler” and have installed a foster fitting allowing me to void the air tank directly into the Yong Heng once the tank is at atmospheric pressure of 1 bar.

Thank you in advance for any additional guidance on this very important and commonly neglected task.
 
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7 and 3/4 fills? Not 8 fills or 7 fills…….. you vacuum pump every 7 and 3/4 fills.
Sounds to me like you are not vacuum pumping your tanks often enough. I vacuum pump my tanks every 5/8’s of a fill. Anything less would just be lazy and irresponsible. I really can’t believe you are publicly admitting to such a lacksadaisical vacuum pumping schedule.
I do not vacuum pump my tanks but I have turned a mostly empty tank upside down and opened the valve and let it empty in that way. My thinking was if there were any moisture in it it would be blown out. I did not detect any measurable amount of moisture.
 
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I worked part time in the local dive shop for ten years. I inspected well over 2,000 aluminum and steel scuba tanks and a fair number of SCBA’s for the local UPS depot. Not one single tank in all that time and quantity had ANY water in it. I occasionally washed tank interiors for customers that were going to have nitrox mixed in their tanks via partial pressure mixing. To dry tanks we had a tank dryer I built using the guts from a blow dryer.
If you’re getting water, you need to add a dessicant drier to your compressor. Air Tanks for Sale has two different models the last time I checked.
 
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pnwairgunner said:
7 and 3/4 fills? Not 8 fills or 7 fills…….. you vacuum pump every 7 and 3/4 fills.
Sounds to me like you are not vacuum pumping your tanks often enough. I vacuum pump my tanks every 5/8’s of a fill. Anything less would just be lazy and irresponsible. I really can’t believe you are publicly admitting to such a lacksadaisical vacuum pumping schedule.
I do not vacuum pump my tanks but I have turned a mostly empty tank upside down and opened the valve and let it empty in that way. My thinking was if there were any moisture in it it would be blown out. I did not detect any measurable amount of moisture.
Click to expand...
ANY water is unacceptable in a scuba or carbon fiber tank.
 
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SilentSquirrel said:
How about a PTO (power take off) accessory on a Yong Heng to drive a vacuum pump?
Fill one bottle while drying another at the same time!
I my arithmetic is correct that = 19/32 of a heads up on the next fill
Click to expand...
Just before I got out of scuba I put together a set up for vacuuming my steel scuba tanks. I just used a refrigeration vacuum pump. Very simple set up.
 
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SilentSquirrel said:
How about a PTO (power take off) accessory on a Yong Heng to drive a vacuum pump?
Fill one bottle while drying another at the same time!
I my arithmetic is correct that = 19/32 of a heads up on the next fill
Click to expand...
I don't want to dissuade you but one concern I have would be you would be pumping the stale, unloved air from the vacuum tank into the donor tank receiving the compressed gas.
 
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LMNOP said:
I don't want to dissuade you but one concern I have would be you would be pumping the stale, unloved air from the vacuum tank into the donor tank receiving the compressed gas.
Click to expand...
I think he was intending to use the motor to drive the vacuum pump. I think. Lotta work to go thru rather than get a simple no moving parts molecular sieve and remove all moisture before it ever gets to the tank.

7865C1F1-6179-49D9-9D5B-D1733E125A81.jpeg
 
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Actually, attaching a PTO and vacuum pump to the Yong Heng would most likely throw the finely balanced crankshaft of the precision compressor out of wack.
A more practical idea would be to run the vacuum pump off a treadmill.
Thereby dehumidifying the tank as well as drying one's sense of humor while exercising.
 
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SilentSquirrel said:
Actually, attaching a PTO and vacuum pump to the Yong Heng would most likely throw the finely balanced crankshaft of the precision compressor out of wack.
A more practical idea would be to run the vacuum pump off a treadmill.
Thereby dehumidifying the tank as well as drying one's sense of humor while exercising.
Click to expand...
This approach is unfortunately all wrong, as inevitably some molecules can still contaminate the system. I vacuum my intake air, and use the exhaust for the fill side of and official YONGIHENG labeled air pump, all but insuring clean, dry and properly vacuumed air.
 
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