Shawnusa

My Feedback: (3)

I have a few questions about these Festo fittings.

1. Which size is more used in jets 4 or 6m.
2. If both are common which ones are used for what? I have a simjet 1200 I just bought and it looks like all the fittings are 4mm
3. Can these fittings be used in Prop planes for Gas, Glow or smoke?
4. If not why.
5 Can these fittings be used with air retracts?

I like there simplicity and ease of use and it would be nice to use it in other applications. I just don't see it being done and wondered why.

Thanks,

Shawn

DocYates

My Feedback: (102)

Shawn,
90% of all my fittings are 4 mm. I thnk most of the gas (propane) lines are 4 mm and the larger engines (at least my 750) has 6 mm lines on the kero sytem. What I have learned is that these fitting are primarily pressure fitting, and do not work too well with vacuum. Therefore you should not use them between the fuel pump and the fuel tanks, and they should be on the output side of the pump. THe pressure in the lines help keep the festo fitting secure. I found on the vacuum side of the pump I would get bubbles in the line. They work great and are something that I to only discovered after getting into turbine. BV's website has a nice selection of different ones including some for bulkheads. I don't see why they would not work with retracts or glow fuel, I just have never tried them before.
Tommy

Vampire

My Feedback: (2)

Shawn,

ALL tubing used w/ the SIMJET-1200 is 4 mm.

Yes, these fittings can be used for air retract systems as this is what their primary design function is - air systems and Robart does advertise similar fittings for their air systems.

I do not know what the material compatability is for use w/ GAS or Glow but smoke fluid is not a problem.

Woketman

My Feedback: (6)

1) On most KJ-66 engines, both 4 mm & 6 mm are used. 6 mm generally before the fuel pump and 4 mm after.

2) Doc Yates is correct: these fittings are intended for positive pressure use. But they can be successfully used on the vacuum side. Just be sure that you have a nice undamaged tube surface cut square with no severe bends adjacent to the Festo.

3) I would imagine gas would be fine (never tried), not sure if glow would attack the O-ring.

4) There are smaller ones (2 or 3 mm) that I have seen used for retracts. You could use 4 & 6 mm, but would have to adapt down the line size for our normal 1/16" barbed nipple.

dbarrym

My Feedback: (47)

After "discovering" Festos, I liked them so much I used them everywhere...until I lost a model due to flameout on takeoff that I was able to trace back to a leaky Festo. I now only use them where absolutely necessary in my fuel systems (both pressure and suction). Just my personal opinion.

On the other hand, I still like and use the 3mm Festos for plumbing the air system, particularly for connections to the air valves on my radio trays - makes the trays much easier to remove and re-install. I have found that the smaller sizes are much more sensitive to variations in tubing fit, I have had batches of 3mm air line (from both BVM, Arts, Mcmaster-Carr, etc) that just would not seal correctly. I still would not use them for connections that see a lot of "cycling" (like removable wing air line fittings) as the sealing O-rings seem to wear quickly when used this way.

barry

Shawnusa

My Feedback: (3)

Thanks for the feedback. Since it appears very few have tried it I might give it a whirl and see how it goes on a test stand for a couple of hours over a period of month doing Gas engine tests and see what happens.

Shawn

Instructor

My Feedback: (16)

Hi Doc,

I recently purchased a BVM Mig from RCU. This plane came already plummed. I noticed that there were festo fittings on the UAT to the pump. Also the saddle tanks were hooked up in a Y. The vent lines were hooked up a Y also, but they went to the pickup of the main tank. I have been flying mostly Boomerangs and Kangaroos. Only the kangaroo uses two tanks. They are hooked up in series. Should I be concerned about the festo fitting on the UAT? Also, there was a festo cap on the fill line. Should I take that cap off and use a plug? I use only plugs in my fill line, and I haven't had any problems sucking air.

Thanks,,
Larry.

P.S. I use to live in Florence Alabama......

GrayUK

Festo fittings should not be used on suction sections of your systems.

Although they may function they are designed to seal with positive pressure not negative.

Paul

lear31A

My Feedback: (123)

Thanks for asking Shawn! Great discussion, I have learned a few things! I have wasted soo much money ordering the wrong size lines,fittings, hatch latches,etc. I am learning as i go, its just expensive!

Woketman

My Feedback: (6)

Paul is correct: they are not intended for use on the suction side. However, with some caution (cut square, never have a tight bend adjacent to a fitting, etc.) they can be used safely on the suction side. Been doing it for ten years. Only had an issue once (too tight a bend adjacent to fitting, OOPS!!!).