X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mu-out-0910.google.com ([209.85.134.191] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2377953 for flyrotary@lancaironline.net; Tue, 09 Oct 2007 16:09:50 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.134.191; envelope-from=wdleonard@gmail.com Received: by mu-out-0910.google.com with SMTP id w8so2288944mue for ; Tue, 09 Oct 2007 13:09:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; bh=GC343YHUZFEsPoJ7IScGeM28/daHi5GzRAslotHJFFE=; b=mBy6m3uSnVSwGr8avELKFuFx5M45CclgsbsevhfpFZvm60GBQ710NVFUnUhgHlZU5EFUs8cxsgR89q6tNj/Y9jRJnSbwrJX2mAKPBGwFNLDGTzsyXrXE5vTdJcBCsFo7o7IabCvKTy8jUUsh734+7ZPej9JLUrjFFljNhDIKQA4= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:in-reply-to:mime-version:content-type:references; b=KaYfMTkee0l73SsR7kUd3V5aKWdE4RVMfWt8nJzSw7pasq7G3Z1GIV4i2IPGv1VmJS2dF8ggkwQNARZQQBs+HpdZjgIHFdzYm+k/9oQuKojhJhQ9pIF0mwZwUIvCKhw+oNkByD6VFieKGGNKYFr6EizloGF9PnS4Ms6EZh0dIH0= Received: by 10.82.175.17 with SMTP id x17mr8444694bue.1191960548512; Tue, 09 Oct 2007 13:09:08 -0700 (PDT) Received: by 10.82.122.16 with HTTP; Tue, 9 Oct 2007 13:09:08 -0700 (PDT) Message-ID: <1c23473f0710091309m2bbc2158g38979ad56f560d5b@mail.gmail.com> Date: Tue, 9 Oct 2007 13:09:08 -0700 From: "David Leonard" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Gates "rubber band" clamp Re: Hose clamp myth busters In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_7098_16204693.1191960548501" References: ------=_Part_7098_16204693.1191960548501 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline That stuff looks pretty cool Tracy. I use Oetiker type clamps and like them. Also light weight and self-adjusting one-time use. require a $25 installation/removal tool. http://www.pep-plastic.com/manufacturers/newage/oetiker.htm I have no power at my hangar so heat gun use is out of the question for the gates type clamps. Dave Leonard On 10/9/07, Ed Anderson wrote: > > 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 ----- > *From:* Tracy Crook > *To:* Rotary motors in aircraft > *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 h= ose > 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 loo= sen > 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. > > Only place I don't use them is on oil lines but of course I use no clamp= s > 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, t= hey > are the only thing I'd use. > > Tracy (starving - Laura on 8 day trip to Hawaii) > > > > On 10/7/07, Thomas Jakits wrote: > > > > 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 th= e > > cooler) and the turbine oil to cooler hoses clamped with 2 regular clam= ps on > > each end. Though the hoses are capped off with a metalcap that has to p= rongs > > that go under the clamps, just to hold the cap on the hose end. > > Constant pressure is good, but good regular clamps will do fine. You ca= n > > 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 > > 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 > > > > > > On 10/7/07, Mark Steitle wrote: > > > > > > Al, > > > 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 j= ust a > > > belt and suspenders kind of guy. I like the fact that they adjust to= the > > > expansion. > > > > > > Mark S. > > > (I used "Wiggins" couplings) > > > > > > > > > On 10/6/07, Al Gietzen wrote: > > > > > > > > If those hose clamps are not constant torque clamps, please > > > > consider upgrading them before first flight. They're available fro= m > > > > McMaster. > > > > > > > > > > > > > > > > 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 o= ther list > > > > makes a big issue of the constant torque clamp. IIRC, the main poi= nt 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 co= ld 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 hos= e is > > > > entirely negligible. And besides, having that clamp just a wee smid= geon > > > > tighter when it is hot and pressurized can't be a bad thing. > > > > > > > > > > > > > > > > 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. > > > > > > > > > > > > > > > > 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 coo= lant 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 annua= l or so > > > > anyway. > > > > > > > > > > > > > > > > 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 groun= d. > > > > > > > > > > > > > > > > Sorry; did I go on too long J? > > > > > > > > > > > > > > > > Al G > > > > > > > > > > > > > --=20 David Leonard Turbo Rotary RV-6 N4VY http://N4VY.RotaryRoster.net http://RotaryRoster.net ------=_Part_7098_16204693.1191960548501 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline That stuff looks pretty cool Tracy.  I use Oetiker type clamps and lik= e them.  Also light weight and self-adjusting one-time use.  requ= ire a $25 installation/removal tool.

http://www.pep-plastic.com/manufacturers/newage/oetiker.htm

I ha= ve no power at my hangar so heat gun use is out of the question for the gat= es type clamps.

Dave Leonard



On 10/9/07, Ed Anderson <eanderson@carolina.rr.com> wrote:
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 w= eight a=20 little too far? {:>)  Hey, I could fly down and then we could go ou= t for=20 BBQ - hate to see you starve.
Here is some information on them for anybody=20 interested
 
 
Ed
----- Original Message -----
From:=20 Tracy=20 Crook
Sent: Tuesday, October 09, 2007 10= :37=20 AM
Subject: [FlyRotary] Re: Hose clam= p myth=20 busters

Am I the only fan of Gates 'Power Grip' hose clamps?  T= hey are heat=20 shrinkable sleeves made for this application.
 
They have everything I like in a hose clamp except one  (they a= re=20 not reusable) (OK, maybe two, every hose size needs a different clamp par= t=20 number and size)
 
They are the  lightest, have constant grip force, most eve= nly=20 distributed clamping force of all types, widest grip area, low in cost (i= f=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=20 wiring.  I know of no failures of these clamps.    Th= ese=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 con= stant=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.thjaki= ts@gmail.com>=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/fr= om=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 tha= t has=20 to prongs that go under the clamps, just to hold the cap on the hose en= d.=20
Constant pressure is good, but good regular clamps will do fine. Y= ou=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 ever= y=20 flight, safetywire will give you some peace of mind..
 
Wiggins is the "smoothest" custom touch though! Max poin= ts for coolness=20 too.
 
Sometimes cool is nice, even if you need "people in the know&= quot; to=20 appreciate details like "Wiggins"
 
Cheers,
 
TJ

 
On 10/7/07, Mark=20 Steitle <msteitle@gmail.co= m >=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 rig= ht.  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 const= ant 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 s= old.=20  Certainly not picking on you, and I know our friend on the ot= her=20 list makes a big issue of the constant torque clamp.  IIRC, th= e=20 main point raised was the effect of thermal expansion, more exactly= the=20 differential thermal expansion between the inner metal tube (alumin= um in=20 this case) and the clamp (usually SS).  Doing the math will sh= ow=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 may= be=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 a= m 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 tigh= ter=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, mos= tly=20 over the first few months, and then very slowly over the next few y= ears=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= 9;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 autom= otive=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 ho= ses=20 every second annual or so anyway.

 

One more=20 thing.  Consider putting a Schroeder valve on the system somew= here=20 so you can easily pressure test the system before you fly (or befor= e you=20 start your engine), and maybe at annual time.  It is so much e= asier=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


=





--
David Leonard

Tu= rbo Rotary RV-6 N4VY
http://N4V= Y.RotaryRoster.net
http://Rotary= Roster.net ------=_Part_7098_16204693.1191960548501--