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Purge Valve?

J

josnooze

Member
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I am working on the FWF portion of my RV 10 build and wondering if anyone out there is using a purge valve with the FM-150 throttle body from Air Flow Performance. The FM-150 does not require a purge valve unlike the FM-100 on my current RV-9 but seems to be useful for hot starts. Any experience out there?
 
I used a purge valve on the first build (RV-8A). I rarely used it. The current RV-8 uses the very nice AFP FM-150C. It does not have a purge valve and I never miss it. Hot starts are not a problem once you practice proper procedure.

Carl
 
I use the purge valve and like it

I installed a purge valve on my IO-370 with the FM-150 and I like having it.

It makes hot starts a little easier, especially in hot weather. You can circulate fuel through the system so that you are not trying to start using hot fuel. It also makes for a clean shutdown and you don’t need to worry about fuel dripping into the air box after shutdown.
 
Keep it simple. Less things to go wrong is always better. My vote is no purge value. I've been flying my fuel injected RV7 for 650hrs and have not missed it at all.
I had a AFP purge valve mishap in Dec 2006 which resulted in destroying my beautiful RV4.
 
Wiley E said:
Keep it simple. Less things to go wrong is always better. My vote is no purge value. I've been flying my fuel injected RV7 for 650hrs and have not missed it at all.
I had a AFP purge valve mishap in Dec 2006 which resulted in destroying my beautiful RV4.
Click to expand...

Wiley, what was the nature of the mishap? The knowledge may prevent another loss.
 
Kahuna said:
https://vansairforce.net/community/showthread.php?t=17931https://vansairforce.net/community/showthread.php?t=17931

I also had a dead stick from the purge valve. Ill not use it again. There are a number of banged up planes Im personally aware of. Its been a while since Ive heard of any failures. Design change or less use? I don't know.
Click to expand...

I can't speak for everyone, but after reading about these failures I made sure to install the purge valve using the best cable available, and I carefully read and did everything listed in the book. I use the purge valve to shut down the engine every time. I rarely use it for "hot starts". If I were doing it again, I would not install the purge valve, but I don't feel strongly enough about it to remove it from my aircraft.

Old photos of some purge valve installations showed use of the infamous "lawnmower" cables. I would strongly recommend using a good aviation-quality cable, with a lot of thought about failure modes if something comes loose.
 
Thanks to all for the feedback. After talking with Don at AFP I will proceed without the purge valve install. Just curious Karl what is your hot start procedure?
 
I'm a big fan of the purge valve and have used it on both of my engines, but like many things on our aircraft, poor installation practices can/will create problems. The only failures I am aware of (above) have been caused by poor installation.
(Note: McFarlane locking purge cable)

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Use a quality cable

I've had the purge valve on multiple aircraft. I currently have it on the RV10 with over 2300 hrs on it. The key is to use a quality cable with a proper rod end bearing on it. NO lawnmower/choke cables. Also, place a spring on it so it will be spring loaded to the ON position.
It makes hot starts as easy at cold starts.

Vic
 
vic syracuse said:
I've had the purge valve on multiple aircraft. I currently have it on the RV10 with over 2300 hrs on it. The key is to use a quality cable with a proper rod end bearing on it. NO lawnmower/choke cables. Also, place a spring on it so it will be spring loaded to the ON position.
It makes hot starts as easy at cold starts.

Vic
Click to expand...

Vic, I like the spring idea. I'd like to get a spring similar to what we have on the prop controller, I believe they are called a "torsion spring." It seems most people use a "tension spring" - like on a screen door. Perhaps it's something we can get Don to consider.
 
vic syracuse said:
I've had the purge valve on multiple aircraft. I currently have it on the RV10 with over 2300 hrs on it. The key is to use a quality cable with a proper rod end bearing on it. NO lawnmower/choke cables. Also, place a spring on it so it will be spring loaded to the ON position.
It makes hot starts as easy at cold starts.

Vic
Click to expand...

+1 for the spring. I have had one on my purge valve for years. I also used a quality cable with a rod end bearing. The purge valve makes hot starts a non-issue.

YMMV
 
josnooze said:
I am working on the FWF portion of my RV 10 build and wondering if anyone out there is using a purge valve with the FM-150 throttle body from Air Flow Performance. The FM-150 does not require a purge valve unlike the FM-100 on my current RV-9 but seems to be useful for hot starts. Any experience out there?
Click to expand...

I had it installed on mine. Worked great, no issues. As others have said, good quality cable and follow the instructions and you wont have issues.
 
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