Show us your 6/7/9 duplex valve install

It seems there are plenty of photos showing installs of the duplex Andair valves in the -10 and -8, but not so many in the SBS models. With the rise of SDS and EFII installs, there must be folks out there stuffing them into 6, 7, and 9's, so if you've done it successfully, post a photo or two?

Thinking about how to replace a single Andair valve with a duplex and how to fit all the plumbing in the space available. Also interested in notes from anyone who retrofit the 3/8 return line into a completed tank.

Check with Tom at TSFlightLines.

I am working on fuel system right now on my RV-6A. I purchased the center console parts for an RV-7A. You can check out my Kitlog site. See link below. You cannot bend the tubing 90 degrees and make the valve fit the Van's parts. Originally I purchased 6 swivel street AN fittings but the assembly was about 3/16" too wide to fit into with the stock Van's parts . I had to order the 90 degree elbow attachments from Andair to make the valve fit into the stock Van's parts. When I received the parts from Andair they sent me the wrong ones. Now I am waiting on the replacement parts.

Duplex valve mocked up

I received the parts from Andair. I installed the valve into the Van's parts and there will be enough clearance to run the 3/8" tubing. Hopefully I will get some time this weekend to work on the plumbing.

Her is a pic how I installed a duplex valve in my -7. I recut the threads on the AN822 fittings to get them a little deeper into the valve and to clear the tunnel. Today I would use elbow or Banjo fittings like on the pic from 219PB above.

We have a package for the 7/9 installs. Gee one of these days I'll figure out how to post pics here. It all fits under the stock overs. Only real issue is we like to use the EF20 elbows from Andair, and they are pricey. (Andair is supposed to be marketing a duplex valve that includes these elbows.) BUT---it cleans up the install. We install the elbows pointed aft towards the spar, and make rigid tubes to route through the standoff brackets. We then crimp teflon hose onto the rigid tubes and route them out the the wings. Also available for the wanting inverted fuel. Maybe I'll get Steve to post some pics.
Tom

Here are some pictures of a duplex installation for the RV7/9 that Tom is referencing.







If you are interested in this setup, Tom has them available.

As a bit of a sneak peak into what we are working on..... we are creating mock ups of various aircraft cabins so we can test fit different components and packages. Once we have something we like, we are creating cad drawings of the tube components and then machining and bending them on CNC machines. We started doing this for the RV14 with drop in cabin fuel line components, and are now working our way through different aircraft with some of the most popular and difficult configurations so that we can offer our customers a complete drop in package.

We will post some videos and more information early next year showing some of these projects.

Happy Thanksgiving and Happy Building

In the interest of avoiding possible vapor lock issues, especially at high altitudes and when burning Mogas, we feel it's best to minimize the use of 90 degree fittings on the inlet side of the pumps. Does not matter on the return side.

Ross, we agree. One of the constraints was to make sure that all of this plumbing fit under the stock covers. Using the standard FS2020 valve with the straight male fittings wasnt going to work. There just wasnt enough room to come off the male and stuff all of this plumbing inside the covers. We even played with using 90* swivel adapters to route the lines. We found that the side clearance was very close. Honestly havent mocked up the banjo fittings, but the dimensions are close to that of the ports with elbow AN fittings. Our point was to NOT use standard AN elbows to help with the flow. So we used the EF20 elbows and our bent rigid tubes to help the bend transition. Hose and 90* hose ends just wont bend tight enough to safely make the bends.
All of that was considering that builders were using the stock covers. Several have decided not to use them, or using some sort of console where the covers werent necessary. But most builders want to use the covers, so we had to compromise on what we could do.
Tom

To Ross' point however, this is a critical thing. If you define a requirement (like no 90's on the inlet), and cant meet that requirement within the available envelope, then you need to redesign the envelope or abandon the concept.

I have not seen any hard data on just how critical a pair of 90's is on the suction side, but I do know enough that it is generally to be avoided as a design principle. And certainly altitude, temperature, fuel type, flow rate and individual builder variation all have a strong influence on how this will work. Some will be fine, some will have issues.

I'm going through this right now on the Rocket and I'm moving the selector to put it in a more favorable position. There will be no 90's in my system.

At the very least this installation should be constructed with a healthy dose of caution and fanatical attention to detail in all other areas to avoid any more restriction. Keep the remaining lines as short and straight as possible, and make sure flight test is conducted in a thorough manner.

Being in the 'plumbing' business, I'd like to throw a few things out there.

First off, I would love to have the resources to make a full scale mockup of both the standard injection system, and of the electronic systems with returns, and have Don Rivera do a flow and suction test. We then would have hard data, but only of the mockup. That data may not translate to all of us.

With the wide variety of accessories available to the builder, it makes developing and plumbing these packages tougher. Think about it.
WE used to ask if it was carbed, or injected, and what selector valve is used.
Now, we ask the same, but add, inverted fuel, and if so, left or right, or both, what boost pump and filter package, and if a console is used. OR is the selector valve in the stock location?

If all the RV7s were equipped the same it wouldnt matter. If all the RV8's were the same it wouldnt matter. The problem is, if you use something that isnt in the plans, or deviates from the plans, it becomes a different scenario to solve. The RV7/9 cabins with the duplex valves are a tough project. We dont have the ONLY solution, I'm quite certain there are others. But, for the constraints we were given, we worked through a bunch of options and came up with one that was relatively simple, was reliable, and wouldnt break the budget, and would solve the problem for MOST builders. Not all, but most. Its time consuming to do a custom install for each builder. Literally, you would have to be onsite to do most of the work. That isnt feasible, we tried it. Some of you know what I'm talking about.

Its experimental aviation, not production. I would almost bet that if you took all the 'like' models of RV's at Oshkosh, none would be exactly alike. Unlike a Cirrus, Piper, Cessna, Beech, etc. And I guess thats why we like it.

So---I personally think its fine to put on the forum an idea and get some opinions. I know I have, both good and bad. But, I've learned from both, and have tried to apply that to what we do. None of us knows it all, there are just too many systems and variables now. But, somewhere, someone has run across what you are trying to do, and has an opinion on it.

Toobuilder said:

To Ross' point however, this is a critical thing. If you define a requirement (like no 90's on the inlet), and cant meet that requirement within the available envelope, then you need to redesign the envelope or abandon the concept.

Click to expand...

Is the requirement "no 90's" or is the requirement "to minimize the use of 90 degree fittings"? With the photos shown, the fuel path only involves one or two 90 degree fittings.

Interestingly, the EFII electric boost pump module is available with a 90 degree fitting on the inlet side.

Hi Tom,

If you were to turn the Andair duplex valve 45 degrees to the right, you would end up with a lot more room for bends (maybe eliminating the 90 fittings altogether) because the fittings are now in the corners of the stock enclosure. As a bonus, the selector now points left for the left tank, right for the right tank.

Bevan

Andrew Anunson said:

Is the requirement "no 90's" or is the requirement "to minimize the use of 90 degree fittings"? With the photos shown, the fuel path only involves one or two 90 degree fittings.

Interestingly, the EFII electric boost pump module is available with a 90 degree fitting on the inlet side.

Click to expand...

The requirements are defined by the designer. In my case, "zero" 90's is my requirement since I am planning to run auto fuel at high ambient temps at altitude and feeding a 540. Almost the worst case possible. My only point for posting in thread is to point out that when performance of a system is impacted by convenience, then one needs to take a hard look at just how stringent the performance requirement really is. Yes, it is always best (from a flow perspective) to "minimize" the use of 90's. However, that is of little comfort when your minimum is 3 and the increased delivery demands you have created chokes the system.

However, none of this is intended to impune Tom's product or cause alarm. It certainly appears to be an excellent plumbing solution for a tough situation. This does illustrate the need to look at the aircraft as a system however. The further off plan you go, the more stuff you need to consider.

Toobuilder said:

In my case, "zero" 90's is my requirement since I am planning to run auto fuel at high ambient temps at altitude and feeding a 540. Almost the worst case possible. My only point for posting in thread is to point out that when performance of a system is impacted by convenience, then one needs to take a hard look at just how stringent the performance requirement really is. Yes, it is always best (from a flow perspective) to "minimize" the use of 90's. However, that is of little comfort when your minimum is 3 and the increased delivery demands you have created chokes the system.

However, none of this is intended to impune Tom's product or cause alarm. It certainly appears to be an excellent plumbing solution for a tough situation. This does illustrate the need to look at the aircraft as a system however. The further off plan you go, the more stuff you need to consider.

Click to expand...

Excellent post... thanks for describing your circumstances. Have you decided to use the 1/2" Andair valve and fuel lines for your 540?