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#42
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On 2/24/2014 7:43 PM, KC wrote:
On 2/24/2014 6:05 PM, Mr. Luddite wrote: On 2/24/2014 5:06 PM, Wayne.B wrote: On Mon, 24 Feb 2014 16:46:48 -0500, wrote: I am starting to prefer the teflon paste. === Yes. I just finished a fairly complex plumbing job on the boat (new distribution manifold for 4 zones of A/C cooling water). It has more than 15 individual pipe joints and is driven by a 1 hp pool pump so there is lots of pressure and lots of opportunity for leaks. Knock on wood, everything worked fine with no leaks first time it was powered up. I've always used teflon tape previously but I've had my share of failed joints with that. Teflon tape is tricky to use properly. It is often used in the high vacuum industry for all the feedthrough fittings that need to seal against a vacuum equivalent to 200 miles in space to atmospheric pressure. Too little tape, it leaks. To much it leaks. One secret is to wrap it in the direction of the thread, so when you are tightening the connection fitting, the tape is not being stretched back against itself. We couldn't use Teflon paste because it never completely cures and would outgas into the vacuum. So, is the end of the tape facing the direction of twist, or away from the direction of twist... I am confused. The end of the tape wrap will be *away* from the direction of twist to install the fitting. |
#43
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posted to rec.boats
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I was trying to imitate your cackling , Johnny.
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#44
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posted to rec.boats
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On 2/24/2014 7:52 PM, wrote:
On Mon, 24 Feb 2014 18:05:10 -0500, "Mr. Luddite" wrote: On 2/24/2014 5:06 PM, Wayne.B wrote: On Mon, 24 Feb 2014 16:46:48 -0500, wrote: I am starting to prefer the teflon paste. === Yes. I just finished a fairly complex plumbing job on the boat (new distribution manifold for 4 zones of A/C cooling water). It has more than 15 individual pipe joints and is driven by a 1 hp pool pump so there is lots of pressure and lots of opportunity for leaks. Knock on wood, everything worked fine with no leaks first time it was powered up. I've always used teflon tape previously but I've had my share of failed joints with that. Teflon tape is tricky to use properly. It is often used in the high vacuum industry for all the feedthrough fittings that need to seal against a vacuum equivalent to 200 miles in space to atmospheric pressure. Too little tape, it leaks. To much it leaks. One secret is to wrap it in the direction of the thread, so when you are tightening the connection fitting, the tape is not being stretched back against itself. We couldn't use Teflon paste because it never completely cures and would outgas into the vacuum. The vacuum in outer space is 14.7 PSI if you maintained 1 BAR in the vessel. . That is not really much. The galvanized piping in my shop air system runs 150 PSI and it is tight. I have done plenty of piping with teflon tape and this is really the first time I had a problem. When I put the calipers on the fitting it was about .040-.050" bigger than the threads on a female adapter at the top of the stack. I have an incident open at Hayward but they haven't come up with an answer. Using the pipe nipple does seem to be a good work around tho. I wish I had started out that way and this would have been a 45 minute project, not 4 days. In a high vacuum chamber the delta P is not the issue. The issue is prevention of any gas molecules leaking or permeating through seals into the vacuum. An air compressor system or a water tight fitting can still have a leak that looks like the Grand Canyon in terms of an opening to a helium gas molecule and will prevent the vacuum chamber from achieving it's ultimate vacuum state. A good vacuum cleaner can draw a vacuum that is 14.6 PSI delta. It's getting to 14.66666666666669 that is difficult. |
#45
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On 2/24/14, 8:11 PM, True North wrote:
I was trying to imitate your cackling , Johnny. You mean the "hehehehehe" thingie he does? hehehehehe |
#46
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On Mon, 24 Feb 2014 17:11:16 -0800 (PST), True North wrote:
I was trying to imitate your cackling , Johnny. No explanation necessary, Don. I just figure you've got a sinus infection or a more severe plugged nose problem. |
#47
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#48
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#49
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posted to rec.boats
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On 2/24/2014 8:02 PM, Mr. Luddite wrote:
On 2/24/2014 7:43 PM, KC wrote: On 2/24/2014 6:05 PM, Mr. Luddite wrote: On 2/24/2014 5:06 PM, Wayne.B wrote: On Mon, 24 Feb 2014 16:46:48 -0500, wrote: I am starting to prefer the teflon paste. === Yes. I just finished a fairly complex plumbing job on the boat (new distribution manifold for 4 zones of A/C cooling water). It has more than 15 individual pipe joints and is driven by a 1 hp pool pump so there is lots of pressure and lots of opportunity for leaks. Knock on wood, everything worked fine with no leaks first time it was powered up. I've always used teflon tape previously but I've had my share of failed joints with that. Teflon tape is tricky to use properly. It is often used in the high vacuum industry for all the feedthrough fittings that need to seal against a vacuum equivalent to 200 miles in space to atmospheric pressure. Too little tape, it leaks. To much it leaks. One secret is to wrap it in the direction of the thread, so when you are tightening the connection fitting, the tape is not being stretched back against itself. We couldn't use Teflon paste because it never completely cures and would outgas into the vacuum. So, is the end of the tape facing the direction of twist, or away from the direction of twist... I am confused. The end of the tape wrap will be *away* from the direction of twist to install the fitting. Good.. Cause that's the way I been doing it all my life ![]() |
#50
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