Holding a vacuum with Bluvac

[belmont1611]

I recently purchased the Bluvac and immediately I have seen how this gauge is changing the way I pull down a system. I hooked it up to my digicool manifold with standard hoses just to test it out. It took around 5 minutes to pull 500 microns on my gauges. After I shut my pump off and tested to see how well it could hold a vacuum I was surprised to see that even though I was holding 29 Hg I was climbing up past 1500 microns on the bluvac. So my question is why can I not maintain a better micron rating is it because my hoses aren't vacuum rated or something along those lines. I would be very thankful for some feedback on how others use the bluvac.

[belmont1611]

Forgive me I should have posted this in the test equipment thread.

[hvacrmedic]

You would have gotten the same result with any other micron gauge. Try putting pressure on the manifold and hoses and then check the whole thing with bubble solution, including the hoses. You'll be surprised at what you see.

[PMARS2345]

If you are serious about pulling a proper vacuum (which not everyone is) in my limited experience, you have to have vacuum rated hoses. Why wouldn't you anyways, can pull down much faster and holds better. After being frustrated with lengthy evacuations I bought some appions and the time saved was amazing.

[mark beiser]

Try putting pressure on the manifold and hoses and then check the whole thing with bubble solution, including the hoses. You'll be surprised at what you see.

If they cheap ones like Yellow Jacket PlusII charging hoses, a bazillian tiny bubbles from the hose, and a giant one at the crimp connection at each end!:gah:

The NRP hoses I use are non permeable, and have fewer issues with leaking at the crimp connection because they use an 8 point instead of 6 point crimp, but I still sometimes have issues with them.

No hose that has been used for refrigerant will ever be worth a damn for pulling a deep vacuum though, regardless of its permeability.

[hvacrmedic]

If they cheap ones like Yellow Jacket PlusII charging hoses, a bazillian tiny bubbles from the hose, and a giant one at the crimp connection at each end!:gah:

The NRP hoses I use are non permeable, and have fewer issues with leaking at the crimp connection because they use an 8 point instead of 6 point crimp, but I still sometimes have issues with them.

No hose that has been used for refrigerant will ever be worth a damn for pulling a deep vacuum though, regardless of its permeability.

A bazillion tiny bubbles in a perfectly arranged regular pattern. :)

[mark beiser]

A bazillion tiny bubbles in a perfectly arranged regular pattern. :)

I've been using the same Yellow Jacket charging hose for connecting my "burnout" recovery machine to my "mixed/burnout" recovery tank for years now.

The pattern of tiny frost bubbles that form on the hose is kind of amusing.

I'd replace the hose, but it saves us money on mixed/burned refrigerant disposal, probably only a few ounces per use, but still...:whistle:

[hvacrmedic]

I've been using the same Yellow Jacket charging hose for connecting my "burnout" recovery machine to my "mixed/burnout" recovery tank for years now.

The pattern of tiny frost bubbles that form on the hose is kind of amusing.

I'd replace the hose, but it saves us money on mixed/burned refrigerant disposal, probably only a few ounces per use, but still...:whistle:

A coworker demonstrated this to me when I was first starting out in the trade. His explanation was that the outer skin is intentionally perforated to prevent blistering. I once purchased master cool hoses and they blistered on the first use, apparently because they were not perforated. I took them back to the supply house and they immediately pulled their stock permanently from the rack.

[71CHOPS]

also check/replace all of your seals on the hoses if they look suspect.