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rv(at)thelefflers.com Guest
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Posted: Mon Oct 27, 2008 5:59 pm Post subject: Purge Valves |
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I’m in the process of building my tanks at the moment and have been researching how to plumb the purge valve. I didn’t want to have to add anymore lines after I complete the tanks.
I was under the impression that it would be best for the line from the purge valve to be run back to the left tank. If you really want to go with a lavish solution you can run the return lines through the fuel tank switch and let the switch control which tank is connected. Just having it routed to the tank left tank saves $$$ on the andair valve.
In reading the purge valve documentation from AFP, it shows two solutions. The first solution routes the return line to a tee connection in the fuel vent line. My concern with this approach is that I’m not sure what would prevent the fuel not going out the vent line when purging.
The second solution in their documentation has the return line routed to the left fuel line before the fuel selector valve. My concern here is that the hot fuel will get mixed into the fuel line too soon and defeat one of the reasons of for the purge valve in a hot start situation.
I am interested in hearing what others have done in regards to routing the return line and if my concerns are well founded or not.
Thanks,
Bob
#40684
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msausen
Joined: 25 Oct 2007 Posts: 559 Location: Appleton, WI USA
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Posted: Tue Oct 28, 2008 2:53 am Post subject: Purge Valves |
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Bob, many people did option two and routed it back to the line before the selector. Seems to work ok. You wouldn’t have hot fuel circulating as long as you select the opposite tank. In my particular case I plumbed the return to the right tank so when purging hot fuel I would select the left tank to draw from.
Michael
http://www.mykitlog.com/users/display_log.php?user=msausen&project=22&category=0&log=57694&row=22
http://www.mykitlog.com/users/display_log.php?user=msausen&project=22&category=0&log=56523&row=23
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Bob Leffler
Sent: Monday, October 27, 2008 9:01 PM
To: rv10-list(at)matronics.com
Subject: Purge Valves
I’m in the process of building my tanks at the moment and have been researching how to plumb the purge valve. I didn’t want to have to add anymore lines after I complete the tanks.
I was under the impression that it would be best for the line from the purge valve to be run back to the left tank. If you really want to go with a lavish solution you can run the return lines through the fuel tank switch and let the switch control which tank is connected. Just having it routed to the tank left tank saves $$$ on the andair valve.
In reading the purge valve documentation from AFP, it shows two solutions. The first solution routes the return line to a tee connection in the fuel vent line. My concern with this approach is that I’m not sure what would prevent the fuel not going out the vent line when purging.
The second solution in their documentation has the return line routed to the left fuel line before the fuel selector valve. My concern here is that the hot fuel will get mixed into the fuel line too soon and defeat one of the reasons of for the purge valve in a hot start situation.
I am interested in hearing what others have done in regards to routing the return line and if my concerns are well founded or not.
Thanks,
Bob
#40684 = -Matt Dralle, List Admin.[/b][/quote]http://www.matronics.com/con[/b] [b]
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recapen(at)earthlink.net Guest
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Posted: Tue Oct 28, 2008 4:03 am Post subject: Purge Valves |
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I put in the Andair dual valve and plumbed both sides in to the tank and further in to the second bay. I had QB tanks and had to open them up for two SB's and getting my fuel senders aligned.
My thinking was that now I won't have to placard "Select Left tank for purge operations" as it will always go back from where it came. Also, since I had the tanks open to put in a return line, I ran it in to the next bay at the same level to dilute the heat as you have discussed.
I'll be testing my fuel system this weekend - if it passes, the dragon will breathe.....
Ralph Capen
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n223rv(at)wolflakeairport Guest
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Posted: Tue Oct 28, 2008 7:13 am Post subject: Purge Valves |
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This is exactly what we did. It works great with very little additional plumbing and no modifications to the tank. Just be sure the fuel selector valve is on the opposite tank than the return is plumbed to when purging the system.
From: RV Builder (Michael Sausen) <rvbuilder(at)sausen.net>
Sent: Tuesday, October 28, 2008 6:51 AM
To: rv10-list(at)matronics.com <rv10-list(at)matronics.com>
Subject: RE: Purge Valves
Bob, many people did option two and routed it back to the line before the selector. Seems to work ok. You wouldn’t have hot fuel circulating as long as you select the opposite tank. In my particular case I plumbed the return to the right tank so when purging hot fuel I would select the left tank to draw from.
Michael
http://www.mykitlog.com/users/display_log.php?user=msausen&project=22&category=0&log=57694&row=22
http://www.mykitlog.com/users/display_log.php?user=msausen&project=22&category=0&log=56523&row=23
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Bob Leffler
Sent: Monday, October 27, 2008 9:01 PM
To: rv10-list(at)matronics.com
Subject: Purge Valves
I’m in the process of building my tanks at the moment and have been researching how to plumb the purge valve. I didn’t want to have to add anymore lines after I complete the tanks.
I was under the impression that it would be best for the line from the purge valve to be run back to the left tank. If you really want to go with a lavish solution you can run the return lines through the fuel tank switch and let the switch control which tank is connected. Just having it routed to the tank left tank saves $$$ on the andair valve.
In reading the purge valve documentation from AFP, it shows two solutions. The first solution routes the return line to a tee connection in the fuel vent line. My concern with this approach is that I’m not sure what would prevent the fuel not going out the vent line when purging.
The second solution in their documentation has the return line routed to the left fuel line before the fuel selector valve. My concern here is that the hot fuel will get mixed into the fuel line too soon and defeat one of the reasons of for the purge valve in a hot start situation.
I am interested in hearing what others have done in regards to routing the return line and if my concerns are well founded or not.
Thanks,
[The entire original message is not included] [quote][b]
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carl.froehlich(at)cox.net Guest
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Posted: Tue Oct 28, 2008 2:59 pm Post subject: Purge Valves |
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I have 450 hours on my Airflow Performance 8A. I installed a return line to top of the left tank for the purge valve. Returning to either vent line is not a good idea.
That said, I have never had a need to actually purge the engine. I do however use the purge valve for normal engine shut down to bleed the pressure out of the spider. Bottom line is I see no “hot fuel” problem for returning the purge line fuel to a T in the left tank fuel line, nor is there any reason to do the expensive option of having a ganged fuel selector valve.
If you are still building, installing a ¼” bulkhead fitting in the left tank is simple enough to do even if you end up not using a purge valve and just cap it. This is what I did for my 10.
Carl Froehlich
From: owner-rv10-list-server(at)matronics.com [mailto:owner-rv10-list-server(at)matronics.com] On Behalf Of Bob Leffler
Sent: Monday, October 27, 2008 10:01 PM
To: rv10-list(at)matronics.com
Subject: Purge Valves
I’m in the process of building my tanks at the moment and have been researching how to plumb the purge valve. I didn’t want to have to add anymore lines after I complete the tanks.
I was under the impression that it would be best for the line from the purge valve to be run back to the left tank. If you really want to go with a lavish solution you can run the return lines through the fuel tank switch and let the switch control which tank is connected. Just having it routed to the tank left tank saves $$$ on the andair valve.
In reading the purge valve documentation from AFP, it shows two solutions. The first solution routes the return line to a tee connection in the fuel vent line. My concern with this approach is that I’m not sure what would prevent the fuel not going out the vent line when purging.
The second solution in their documentation has the return line routed to the left fuel line before the fuel selector valve. My concern here is that the hot fuel will get mixed into the fuel line too soon and defeat one of the reasons of for the purge valve in a hot start situation.
I am interested in hearing what others have done in regards to routing the return line and if my concerns are well founded or not.
Thanks,
Bob
#40684 Quote: | http://www.matronics.com/Navigator?RV10-List | 0123456789
[quote][b]
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rv10builder(at)bellsouth. Guest
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Posted: Tue Oct 28, 2008 5:49 pm Post subject: Purge Valves |
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I too have the AFP system. I installed a "T" in the right fuel line. For
hot starts I select the left tank and valve open which flushes cool fuel
from the left tank back into the right (follow link below).
http://www.mykitlog.com/users/display_log.php?user=rv10builder&project=7&category=501&log=15056&row=37
Brian Sutherland
Nashville, TN
N104BS - 91 flying hours
Bob Leffler wrote:
Quote: |
I’m in the process of building my tanks at the moment and have been
researching how to plumb the purge valve. I didn’t want to have to add
anymore lines after I complete the tanks.
I was under the impression that it would be best for the line from the
purge valve to be run back to the left tank. If you really want to go
with a lavish solution you can run the return lines through the fuel
tank switch and let the switch control which tank is connected. Just
having it routed to the tank left tank saves $$$ on the andair valve.
In reading the purge valve documentation from AFP, it shows two
solutions. The first solution routes the return line to a tee
connection in the fuel vent line. My concern with this approach is
that I’m not sure what would prevent the fuel not going out the vent
line when purging.
The second solution in their documentation has the return line routed
to the left fuel line before the fuel selector valve. My concern here
is that the hot fuel will get mixed into the fuel line too soon and
defeat one of the reasons of for the purge valve in a hot start situation.
I am interested in hearing what others have done in regards to routing
the return line and if my concerns are well founded or not.
Thanks,
Bob
#40684
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ricksked(at)embarqmail.co Guest
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Posted: Tue Oct 28, 2008 6:04 pm Post subject: Purge Valves |
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Well...almost flying, but I ran mine through the firewall with a AN-4 bulkhead adapter, inside the cabin and out the right wing root and tee'd it to the fuel supply, I also put a check valve from Andair inline to allow fuel to only flow to the tank, not from it. It seemed like a good idea to prevent fuel from being somehow drawn up to the purge valve. I really want to point out that the valve is a critical part of flight for the fuel system. If it should somehow open, you're gonna shut down the engine. I used the same control cable on the valve as I did the throttle and took the same care to run the cable as I did with all the engine/mixture/prop controls. I played with a failsafe closed return spring but ended up getting frustrated trying to find a balanced spring to make it work well in all positions as well as allowing me to operate the control.
Rick Sked
40185
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