Jeff,
Do you know the pressure limitations of your coolers?
Mark
On Tue, Dec 15, 2009 at 7:53 AM, Jeff Whaley <jwhaley@datacast.com> wrote:
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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