X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from an-out-0708.google.com ([209.85.132.246] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2390875 for flyrotary@lancaironline.net; Tue, 16 Oct 2007 22:43:15 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.132.246; envelope-from=rwstracy@gmail.com Received: by an-out-0708.google.com with SMTP id c34so172580anc for ; Tue, 16 Oct 2007 19:42:38 -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:sender:to:subject:in-reply-to:mime-version:content-type:references:x-google-sender-auth; bh=vPHkaNOg150B8fkORkH2inx70LsM0RI9EfTAXkp2ATM=; b=Mqzy+ekRuQ6iYHF+TzWKdOWxUsNjLAKgtT6thhSHs8UOqp8eL47ctx+JYjWg9iAv0Yu25dck9FhPjtSJNqU9SB5yEp6lgDXsUo8Rb95WdOqTzQlYHOiTyNCYGmARJaWNz0o+vp4OCJYWEKiyMaJ6vVWePl6m8KT0YABpi9G3QrE= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:sender:to:subject:in-reply-to:mime-version:content-type:references:x-google-sender-auth; b=X4No73c6z5mnqUTlzPuk9oYlzjgIavouqMs+OTCLNnyAyRqSThCD1EjxkA4TVdJ/qsZL6gZTT9irrUpUhYWQ9wedOHd3iKcWPJTOMqAAvJao+WnIoM23MhUk9t8WZMlAMAjvF73jpCndKG2tegb6mzr8m619x0rKizex5+imDP8= Received: by 10.142.245.10 with SMTP id s10mr2383385wfh.1192588957887; Tue, 16 Oct 2007 19:42:37 -0700 (PDT) Received: by 10.142.144.18 with HTTP; Tue, 16 Oct 2007 19:42:37 -0700 (PDT) Message-ID: <1b4b137c0710161942h4e30832fn1746395edc4d8202@mail.gmail.com> Date: Tue, 16 Oct 2007 22:42:37 -0400 From: "Tracy Crook" Sender: rwstracy@gmail.com To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Hose clamp myth busters In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_4410_14709544.1192588957904" References: X-Google-Sender-Auth: 80363d33e47582b9 ------=_Part_4410_14709544.1192588957904 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Can't speak for Gates but I've used them on both types with no problems. Tracy On 10/16/07, Bobby J. Hughes wrote: > > Tracy, > > Will the Power Grip clamps work with barbed fittings or just the smooth > bead fittings? > > Bobby > (ordering more stuff) > > ------------------------------ > *From:* Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] *O= n > Behalf Of *Tracy Crook > *Sent:* Tuesday, October 09, 2007 8:38 AM > *To:* Rotary motors in aircraft > *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 > > > > > > > > > > > > > > ------=_Part_4410_14709544.1192588957904 Content-Type: text/html; charset=WINDOWS-1252 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline
Can't speak for Gates but I've used them on both types with no= problems.
 
Tracy

 
On 10/16/07, Bobby J. Hughes <bhughes@qnsi.n= et> wrote:
Tracy,
 
Will the Power Grip clamps work with barbed fittings or just t= he smooth bead fittings?
 
Bobby
(ordering more stuff)

From: Rotary motors in aircraft [ma= ilto:flyrotary@lancaironline= .net ] On Behalf Of Tracy Crook
Sent: Tuesday, October 09, 2007= 8:38 AM
To: Rotary motors in aircraft
Subject: [FlyRot= ary] Re: Hose clamp myth busters

 
Am I the only fan of Gates 'Power Grip' hose clamps?  The= y 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 evenl= y distributed clamping force of all types, widest grip area, low in cost (i= f 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 th= ose).  They NEVER loosen and require no checking or safety wiring= .  I know of no failures of these clamps.    These prop= erties 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 const= ant force hose clamps as I do a bumper jack.  If I was a semi truck&nb= sp;driver, they are the only thing I'd use.
 
Tracy  (starving - Laura on 8 day trip to Hawaii)


 
On 10/7/07, = Thomas Jakits <rotary.t= hjakits@gmail.com > 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 t= he cooler) and the turbine oil to cooler hoses clamped with 2 regular clamp= s 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 c= an 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 fl= ight, safetywire will give you some peace of mind..
 
Wiggins is the "smoothest" custom touch though! Max points f= or 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 <msteitle@gmail.c= om > wrote:=20
Al,
Thanks for the analysis.  I always wondered why cars, which use t= he "old fashion" clamps, don't blow hoses left and right.&nbs= p; 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.
(I used "Wiggins" couplings)

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

<= span style=3D"FONT-SIZE: 12pt">If those hose clamps are not constant torque= clamps, please consider upgrading them before first flight.  They'= ;re available from McMaster. =20

<= span style=3D"FONT-SIZE: 12pt"> 

Mark;

 

I have no objection to the use = constant torque clamps, of course.  But I will express my conclusion/o= pinion that this clamp thing has been over sold.  Certainly not pickin= g 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). &n= bsp;Doing the math will show that this is less than infinitesimal.  Th= e 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.&= nbsp; So the aluminum expands about=20 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 t= he thickness of the elastomer hose is entirely negligible. And besides, hav= ing that clamp just a wee smidgeon tighter when it is hot and pressurized c= an'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 month= s, and then very slowly over the next few years =96 depending on the type o= f elastomer, of course.=20

 

So whether they are regular goo= d quality clamps, properly tightened (not over-tightened), or constant torq= ue clamps properly tightened; I'd suggest that the important factors ar= e: 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 althou= gh contemporary automotive coolant hose can be expected to last 6 =96 9 yea= rs.  The other thing, of course, is that on our planes we will probabl= y 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 pressur= e test the system before you fly (or before you start your engine), and may= be at annual time.  It is so much easier to deal with any leak while t= hings are cool and on the ground.=20

 

Sorry; did I go on too long J?

 

Al G



=

 

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