I have a feeling this is a "choose your battles" thing. Used within their
ratings the pushlocks from Parker are a great product. But you have to use
the correct hose with the correct fitting. This leaves the inspector and
even the car owner with the question "is the fitting right?" or "can I read
the markings on the hose?" Go take a look at the pages below and what they
say for temperatures and liquid types.
http://www.parker.com/hpd/literature/pdf/4281_b1.pdf
http://www.ppe.com/pdf06/0302-0303.pdf
Unless you know something better about push-lok hoses I'd say stay away from
them for almost any application in our race cars. Well, I might be willing
to look at the high temperature 836 hose for oil, especially a remote
pressure gauge if I was pretty sure my temperatures would stay well below
the limit for that product.
And I'd be real cautious about tightening hose clamps too much if someone
insisted they be used. I've read where tightening hose clamps over a
push-lok connection defeats the whole purpose and may make the installation
less reliable rather than more. This does have a logical ring to it. IMHO
the tubing reinforcing fibers are pretty highly stressed in tension in the
regions near the barbs in order to put the necessary compression into the
rubber. Shear stresses from a tight hose clamp can only increase the
combined stress levels in the fibers thereby decreasing the safe working
pressure. If I had to use a screw clamp I'd put it as far away from the
outer end of the barbed part of the fitting as possible. It's at the first
barb that fluid pressure and stretching of the hose fibers have the greatest
chance of working together along with added the stresses from a hose clamp
to cause a hose failure at marginal temperature and fluid compatibility
(read methanol fuel contamination of the oil) limits.
Ed Weldon
----- Original Message -----
From: "drmayf" <drmayf@mayfco.com>
To: "Keith Turk" <kturk@ala.net>
Cc: "Dick J" <lsr_man@yahoo.com>; "Doug Odom" <dlodom@charter.net>; "LSR"
<land-speed@autox.team.net>
Sent: Sunday, January 14, 2007 12:34 PM
Subject: Re: Plumbig My Radiator...
> The inspectors who looked the car over thought that it was not necessary
> but they decided to ask the chief inspector, who ever that was, and he
> said unequivacably (sp?) no, clamps were mandatory. Rule 3.R in the book
|