X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.121] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2377386 for flyrotary@lancaironline.net; Tue, 09 Oct 2007 11:05:25 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([24.74.103.61]) by cdptpa-omta04.mail.rr.com with SMTP id <20071009150445.NWUM2011.cdptpa-omta04.mail.rr.com@edward2> for ; Tue, 9 Oct 2007 15:04:45 +0000 Message-ID: <002a01c80a85$c7e91ad0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Gates "rubber band" clamp Re: Hose clamp myth busters Date: Tue, 9 Oct 2007 11:05:07 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0027_01C80A64.40A7DF50" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3138 This is a multi-part message in MIME format. ------=_NextPart_000_0027_01C80A64.40A7DF50 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Yeah, but it ain't traditional {:>), is too light, too resistance to = chemicals and too neat looking - can't imagine why you use them, Tracy. = I mean isn't this carrying your phobia against weight a little too far? = {:>) Hey, I could fly down and then we could go out for BBQ - hate to = see you starve. Here is some information on them for anybody interested http://www.gates.com/brochure.cfm?brochure=3D927&location_id=3D546 Ed ----- Original Message -----=20 From: Tracy Crook=20 To: Rotary motors in aircraft=20 Sent: Tuesday, October 09, 2007 10:37 AM Subject: [FlyRotary] Re: Hose clamp myth busters Am I the only fan of Gates 'Power Grip' hose clamps? They are heat = shrinkable sleeves made for this application. They have everything I like in a hose clamp except one (they are not = reusable) (OK, maybe two, every hose size needs a different clamp part = number and size) They are the lightest, have constant grip force, most evenly = distributed clamping force of all types, widest grip area, low in cost = (if constant hose removal not required) and can be used in tight places = where there is no way to get a tool on them to tighten (I have a few of = those). They NEVER loosen and require no checking or safety wiring. I = know of no failures of these clamps. These properties make them the = clamp of choice for me. =20 Only place I don't use them is on oil lines but of course I use no = clamps at all there (Aeroquip push on connectors and hose) On an airplane, I have as much use for those heavy spring loaded = constant force hose clamps as I do a bumper jack. If I was a semi truck = driver, they are the only thing I'd use. Tracy (starving - Laura on 8 day trip to Hawaii) =20 On 10/7/07, Thomas Jakits wrote:=20 2nd Al's motion, I fly helicopters for a living (the certificated versions ....) The last one has some of the hydraulics system (low pressure to/from = the cooler) and the turbine oil to cooler hoses clamped with 2 regular = clamps on each end. Though the hoses are capped off with a metalcap that = has to prongs that go under the clamps, just to hold the cap on the hose = end.=20 Constant pressure is good, but good regular clamps will do fine. You = can safety wire them too, allthough the ones on the helo are not.=20 Then, I have to do a daily pre-flight inspection that includes to = grap and pull the hoses somewhat. Short work of makeing sure the clamps = are not loose, too. If you do not or cannot preflight the engine like that before every = flight, safetywire will give you some peace of mind.. Wiggins is the "smoothest" custom touch though! Max points for = coolness too. Sometimes cool is nice, even if you need "people in the know" to = appreciate details like "Wiggins" Cheers, TJ =20 On 10/7/07, Mark Steitle wrote:=20 Al,=20 Thanks for the analysis. I always wondered why cars, which use = the "old fashion" clamps, don't blow hoses left and right. I guess I'm = just a belt and suspenders kind of guy. I like the fact that they = adjust to the expansion. =20 Mark S.=20 (I used "Wiggins" couplings) =20 On 10/6/07, Al Gietzen wrote:=20 If those hose clamps are not constant torque clamps, please = consider upgrading them before first flight. They're available from = McMaster. =20 Mark; I have no objection to the use constant torque clamps, of = course. But I will express my conclusion/opinion that this clamp thing = has been over sold. Certainly not picking on you, and I know our friend = on the other list makes a big issue of the constant torque clamp. IIRC, = the main point raised was the effect of thermal expansion, more exactly = the differential thermal expansion between the inner metal tube = (aluminum in this case) and the clamp (usually SS). Doing the math will = show that this is less than infinitesimal. The temp change of the = coolant may be about 80 C cold to hot. The clamp heats up maybe 15C = less than the aluminum. Assume a 1 =BD" diameter. So the aluminum = expands about 0.000037" on the diameter while the SS expands only = 0.000012"; a huge difference of 0.000025". I am certain that this = effect on the thickness of the elastomer hose is entirely negligible. = And besides, having that clamp just a wee smidgeon tighter when it is = hot and pressurized can't be a bad thing.=20 Now, it is true that over time the elastomer loses some of its = elasticity, mostly over the first few months, and then very slowly over = the next few years =96 depending on the type of elastomer, of course.=20 So whether they are regular good quality clamps, properly = tightened (not over-tightened), or constant torque clamps properly = tightened; I'd suggest that the important factors are: re-torque the = clamps after a few weeks or a month of use; use the widest clamp for the = diameter, and consider high quality silicone hose =96 although = contemporary automotive coolant hose can be expected to last 6 =96 9 = years. The other thing, of course, is that on our planes we will = probably change out the hoses every second annual or so anyway.=20 One more thing. Consider putting a Schroeder valve on the = system somewhere so you can easily pressure test the system before you = fly (or before you start your engine), and maybe at annual time. It is = so much easier to deal with any leak while things are cool and on the = ground.=20 Sorry; did I go on too long J? Al G ------=_NextPart_000_0027_01C80A64.40A7DF50 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
Yeah, but it ain't traditional  {:>), is = too=20 light, too resistance to chemicals and too neat looking - can't imagine = why you=20 use them, Tracy.  I mean isn't this carrying your phobia against = weight a=20 little too far? {:>)  Hey, I could fly down and then we could go = out for=20 BBQ - hate to see you starve.
Here is some information on them for anybody=20 interested
 
http://www.gates.com/brochure.cfm?brochure=3D927&location_id=3D5= 46
 
Ed
----- Original Message -----
From:=20 Tracy=20 Crook
Sent: Tuesday, October 09, 2007 = 10:37=20 AM
Subject: [FlyRotary] Re: Hose = clamp myth=20 busters

Am I the only fan of Gates 'Power Grip' hose clamps?  They = are heat=20 shrinkable sleeves made for this application.
 
They have everything I like in a hose clamp except one  = (they are=20 not reusable) (OK, maybe two, every hose size needs a different clamp = part=20 number and size)
 
They are the  lightest, have constant grip force, most = evenly=20 distributed clamping force of all types, widest grip area, low in cost = (if=20 constant hose removal not required)  and can be used in tight = places=20 where there is no way to get a tool on them to tighten (I have a few = of=20 those).  They NEVER loosen and require no checking or safety = wiring.  I know of no failures of these clamps.    = These=20 properties make them the clamp of choice for me. 
 
 Only place I don't use them is on oil lines but of course I = use no=20 clamps at all there (Aeroquip push on connectors and hose)
 
On an airplane, I have as much use for those heavy spring loaded = constant=20 force hose clamps as I do a bumper jack.  If I was a semi=20 truck driver, they are the only thing I'd use.
 
Tracy  (starving - Laura on 8 day trip to Hawaii)


 
On 10/7/07, Thomas=20 Jakits <rotary.thjakits@gmail.com&g= t;=20 wrote:=20
2nd Al's motion,
 
I fly helicopters for a living (the certificated versions = ....)
The last one has some of the hydraulics system (low pressure = to/from=20 the cooler) and the turbine oil to cooler hoses clamped with 2 = regular=20 clamps on each end. Though the hoses are capped off with a metalcap = that has=20 to prongs that go under the clamps, just to hold the cap on the hose = end.=20
Constant pressure is good, but good regular clamps will do = fine. You=20 can safety wire them too, allthough the ones on the helo are not. =
Then, I have to do a daily pre-flight inspection that includes = to grap=20 and pull the hoses somewhat. Short work of makeing sure the clamps = are not=20 loose, too.
 
If you do not or cannot preflight the engine like that before = every=20 flight, safetywire will give you some peace of mind..
 
Wiggins is the "smoothest" custom touch though! Max points for = coolness=20 too.
 
Sometimes cool is nice, even if you need "people in the know" = to=20 appreciate details like "Wiggins"
 
Cheers,
 
TJ

 
On 10/7/07, Mark=20 Steitle <msteitle@gmail.com >=20 wrote:=20
Al,
Thanks for the analysis.  I always wondered why cars, = which use=20 the "old fashion" clamps, don't blow hoses left and right.  I = guess=20 I'm just a belt and suspenders kind of guy.  I like the fact = that=20 they adjust to the expansion. 
 
Mark S.
(I used "Wiggins" couplings)

 
On 10/6/07, Al=20 Gietzen <ALVentures@cox.net>=20 wrote:

If those hose clamps are not constant = torque=20 clamps, please consider upgrading them before first = flight. =20 They're available from McMaster. 

 

Mark;

 

I = have no=20 objection to the use constant torque clamps, of course.  = But I will=20 express my conclusion/opinion that this clamp thing has been = over sold.=20  Certainly not picking on you, and I know our friend on the = other=20 list makes a big issue of the constant torque clamp.  IIRC, = the=20 main point raised was the effect of thermal expansion, more = exactly the=20 differential thermal expansion between the inner metal tube = (aluminum in=20 this case) and the clamp (usually SS).  Doing the math will = show=20 that this is less than infinitesimal.  The temp change of = the=20 coolant may be about 80 C cold to hot.  The clamp heats up = maybe=20 15C less than the aluminum. Assume a 1 =BD" diameter.  So = the=20 aluminum expands about 0.000037" on the diameter while the SS = expands=20 only 0.000012"; a huge difference of 0.000025".  I am = certain that=20 this effect on the thickness of the elastomer hose is entirely=20 negligible. And besides, having that clamp just a wee smidgeon = tighter=20 when it is hot and pressurized can't be a bad thing. =

 

Now, it is=20 true that over time the elastomer loses some of its elasticity, = mostly=20 over the first few months, and then very slowly over the next = few years=20 =96 depending on the type of elastomer, of course. =

 

So = whether=20 they are regular good quality clamps, properly tightened (not=20 over-tightened), or constant torque clamps properly tightened; = I'd=20 suggest that the important factors are: re-torque the clamps = after a few=20 weeks or a month of use; use the widest clamp for the diameter, = and=20 consider high quality silicone hose =96 although contemporary = automotive=20 coolant hose can be expected to last 6 =96 9 years.  The = other thing,=20 of course, is that on our planes we will probably change out the = hoses=20 every second annual or so anyway.

 

One = more=20 thing.  Consider putting a Schroeder valve on the system = somewhere=20 so you can easily pressure test the system before you fly (or = before you=20 start your engine), and maybe at annual time.  It is so = much easier=20 to deal with any leak while things are cool and on the ground.=20

 

Sorry; did I=20 go on too long=20 J?

 

Al=20 = G




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