On many pressure sensing systems I have observed (similar your oil pressure gauge) installations where there are several bends along the copper tube which are plenty enough to take up thermal or vibration or pressure stresses and the entire system mounted on a solid welded machine frame having no vibration from engines or anything else.
Still the loop is present, always oriented below the running path of the tube. Invariably this loop collects fluid from the system and forms a "ptrap" vapour barrier. I see this over and over still I don't know why it is there on a machine that experiences zero vibration. The most recent example was a pressure gauge connected to a horizontal pipe, there was a "T" in the horozontal pipe and a tube formed into a loop with only a gauge atop the loop connected to the skyward facing "T" outlet. The guage was mounted to nothing but the looped tube. Maybe the P trap stops thermal conductivity of hot gases from the source, keeping them from travelling to then far end of the tube and into the gauge. jg On Fri, Dec 17, 2021, 00:25 Gary Sack <garys...@gmail.com> wrote: > OK...copper it will be. > > On Tue, Dec 14, 2021, 5:58 AM Jeff Scott <jscott.pla...@gmx.com> wrote: > > > It is an Experimental, so you can do as you think best; However, the > > industry standard is as described by Randy Smith using a .040" orifice, > and > > connecting with 1/8" copper line with a loop in the line between the > engine > > and firewall to absorb the vibration. It's been successful through 100 > > years of aviation on hundreds of thousands of planes. The loop is a > > critical part of the installation to avoid cracking and failure. > > > > -Jeff Scott > > Arkansas Ozarks. > > > > > > > > > > I enjoy the KR Group because it seems like there are several of you out > > > there who know a whole lot more than me about KR's and airplanes in > > > general. A true resource. Thanks. > > > As to why I don't run copper tubing, it is because it seems much > more > > > likely to fail from vibration and fatigue. Plastic is more likely to > fail > > > from heat, age, and chafing. I am not too concerned about hot oil on my > > > legs because I doubt if the tube will fail in the cockpit. > > > I will check to see if I have a .040 restriction, and while I am at > > it, > > > I might as well replace the line (probably with plastic). And then I > will > > > fly with complete confidence for the rest of my life... I'm pretty old. > > > > > > Gary Sack N81JM > > > > > > On Mon, Dec 13, 2021, 6:47 PM Randall Smith via KRnet < > > krnet@list.krnet.org> > > > wrote: > > > > > > > I am not sure why you would even run a plastic line for your oil > > pressure. > > > > Run it in 1/8 copper and put one loop in it for vibration. Every > > airplane I > > > > have owned has had the same set up whether it was certified or > > > > experimental. I also have always had a fitting with a .040 hole in > it. > > > > > > > > Sent from my iPhone > > > > > > > > > On Dec 13, 2021, at 3:16 PM, Ed Janssen <ejanssen...@gmail.com> > > wrote: > > > > > > > > > > Seems like Steve Bennett told me once that that happened to him > once > > > > while > > > > > flying his KR-1 which made quite a mess and at a high enough rate > > that he > > > > > wanted to get on the ground asap. Some KR drivers have been known > to > > > > > replace plastic tubing annually to lower the risk of that > happening. > > > > Cheap > > > > > precautions. > > > > > > > > > > Ed J. > > > > > > > > > >> On Mon, Dec 13, 2021 at 12:37 PM Gary Sack <garys...@gmail.com> > > wrote: > > > > >> > > > > >> Does anyone know what happens if the plastic capillary tube > sending > > oil > > > > >> pressure back to the cockpit breaks? Mine is old, but in good > > > > condition. > > > > >> It I loose oil pressure reading and make a bit of a mess, I will > > chance > > > > it. > > > > >> If I lose 4 quarts of oil and seize the engine within a few > > minutes, I > > > > >> won't. > > > > >> Gary Sack. N81 JM > > > > >> ________________________________ > > > > >> -Please see LIST RULES and KRnet info at > > http://www.krnet.org/info.html > > > > >> -Change list delivery options at > > > > >> https://list.krnet.org/list/krnet.list.krnet.org/ Affinity List > > Info > > > > Board > > > > >> -Search recent KRnet Archives at > > > > >> https://list.krnet.org/empathy/list/krnet.list.krnet.org/ > > > > >> -Search < > > > > https://list.krnet.org/empathy/list/krnet.list.krnet.org/-Search> > > > > >> John Bouyea's decades of archive at > > > > >> https://www.mail-archive.com/krnet@list.krnet.org/ > > > > >> > > > > > ________________________________ > > > > > -Please see LIST RULES and KRnet info at > > http://www.krnet.org/info.html > > > > > -Change list delivery options at > > > > https://list.krnet.org/list/krnet.list.krnet.org/ Affinity List Info > > Board > > > > > -Search recent KRnet Archives at > > > > https://list.krnet.org/empathy/list/krnet.list.krnet.org/ > > > > > -Search John Bouyea's decades of archive at > > > > https://www.mail-archive.com/krnet@list.krnet.org/ > > > > ________________________________ > > > > -Please see LIST RULES and KRnet info at > > http://www.krnet.org/info.html > > > > -Change list delivery options at > > > > https://list.krnet.org/list/krnet.list.krnet.org/ Affinity List Info > > Board > > > > -Search recent KRnet Archives at > > > > https://list.krnet.org/empathy/list/krnet.list.krnet.org/ > > > > -Search < > > https://list.krnet.org/empathy/list/krnet.list.krnet.org/-Search> > > > > John Bouyea's decades of archive at > > > > https://www.mail-archive.com/krnet@list.krnet.org/ > > > ________________________________ > > > -Please see LIST RULES and KRnet info at > http://www.krnet.org/info.html > > > -Change list delivery options at > > https://list.krnet.org/list/krnet.list.krnet.org/ Affinity List Info > Board > > > -Search recent KRnet Archives at > > https://list.krnet.org/empathy/list/krnet.list.krnet.org/ > > > -Search John Bouyea's decades of archive at > > https://www.mail-archive.com/krnet@list.krnet.org/ > > ________________________________ > > -Please see LIST RULES and KRnet info at http://www.krnet.org/info.html > > -Change list delivery options at > > https://list.krnet.org/list/krnet.list.krnet.org/ Affinity List Info > Board > > -Search recent KRnet Archives at > > https://list.krnet.org/empathy/list/krnet.list.krnet.org/ > > -Search < > https://list.krnet.org/empathy/list/krnet.list.krnet.org/-Search> > > John Bouyea's decades of archive at > > https://www.mail-archive.com/krnet@list.krnet.org/ > ________________________________ > -Please see LIST RULES and KRnet info at http://www.krnet.org/info.html > -Change list delivery options at > https://list.krnet.org/list/krnet.list.krnet.org/ Affinity List Info Board > -Search recent KRnet Archives at > https://list.krnet.org/empathy/list/krnet.list.krnet.org/ > -Search <https://list.krnet.org/empathy/list/krnet.list.krnet.org/-Search> > John Bouyea's decades of archive at > https://www.mail-archive.com/krnet@list.krnet.org/ ________________________________ -Please see LIST RULES and KRnet info at http://www.krnet.org/info.html -Change list delivery options at https://list.krnet.org/list/krnet.list.krnet.org/ Affinity List Info Board -Search recent KRnet Archives at https://list.krnet.org/empathy/list/krnet.list.krnet.org/ -Search John Bouyea's decades of archive at https://www.mail-archive.com/krnet@list.krnet.org/
