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Mark, I have two of the DB-30416, single-pass coolers … no
measureable pressure drop with 2 in series … I’m seeing 80 psi max with
the 13B.
JWW
From: Rotary motors in
aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Mark Steitle
Sent: Tuesday, December 15, 2009 8:36 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Oil cooler
I have the Therm-Hx All-Pro 600 2-pass cooler, p/n DB-30617,
as shown on http://www.fluidyne.com/pl_theoc.html#Therm-Hx%20Engine%20Oil%20Coolers%20DB-30716,%20DB-30617,%20DB-30417.
I've attached a picture of it. It is the one on the right. You can
see how flat the tanks are. The material is very thick, but I can't
get inside to measure it. My guess is .090" - .125".
Strange that this hasn't been a problem for other customers. Like I said
before, I suspect that someone before me over pressurized it during proof
testing. But that's just a hunch.
There's a BTU chart on that page, but no pressure drop
chart. Since I'm reading 90psi at the engine oil filter adapter plate, it
doesn't seem like I've got a problem with pressure drop. But then I haven't
measured oil pressure as it exits the oil pump either.
Thanks for the design tips.
On Tue, Dec 15, 2009 at 12:55 AM, Al Gietzen <ALVentures@cox.net> wrote:
Mark;
Before
buying a new one of the same design, you may want to be sure it is designed to
handle he pressure. If the tank has flat surfaces, even just a few inches
across, it needs to be about 1/8” thick if it is aluminum.
I speced
my custom design aluminum cooler (built by Griffin) for 125 psi. I
pressure tested it to 140. The oil pressure on my 20B will get t0 90+
when cold, and runs 70-80 when hot; and you want some margin, especially since
aluminum is subject to fatigue when cycled – and it is cycled every time
you start your engine and shut it down.
You
might also like to check if they have any pressure drop data. Off-the-shelf
coolers are generally designed for flow rates typical of piston engines,
typically about half of our engines. I recall looking at some data on a
Fluidyne cooler I was considering, and the pressure drop was very high for flow
up to about 16 gpm. If yours was designed for single pass, and modified
for double pass, it could be twice as bad.
Just
some things to check.
Al G
-----Original
Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Mark Steitle
Sent: Monday, December 14, 2009 5:35 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Oil cooler
There's a third possibility that I hadn't considered until I
looked at the cooler again tonight after work. It is evident that the
cooler was pressurized to the point that the tank warped causing the divider to
pull away from the core (not welded where it meets the core). This allowed
the oil to go in and right back out again. The tubes look fine, but the
center of both tanks where there is no support, is ballooned
outward.
I'm debating on whether to send it back to Fluidyne for
inspection & repair, or to bite the bullet and order a new
one (assuming that this size is still available). This one is definitely
repairable, but not sure I'd feel comfortable flying behind it
afterwards.
I also need to ask Gary what the working pressure is for the
Fluidyne coolers. I'm wondering if I may have damaged this cooler with 90
psi oil pressure without realizing it?
On Mon, Dec 14, 2009 at 6:58 PM, Lynn Hanover <lehanover@gmail.com>
wrote:
I called Fluidyne today and spoke with Gary, the owner.
While the cooler is not under warranty, they are willing to look at it and
determine if it can be repaired. I'll send it off and see what they
say.
There should be evidence of a TIG bead half way around the
end tank near the center. Either its there or it isn't. If not and both
fittings are in the same end, it is the problem.......
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