Return-Path: Sender: (Marvin Kaye) To: flyrotary Date: Fri, 29 Nov 2002 22:11:15 -0500 Message-ID: X-Original-Return-Path: Received: from ncsmtp03.ogw.rr.com ([24.93.67.84] verified) by logan.com (CommuniGate Pro SMTP 4.0.2) with ESMTP id 1890598 for flyrotary@lancaironline.net; Thu, 28 Nov 2002 10:08:24 -0500 Received: from mail5.carolina.rr.com (fe5 [24.93.67.52]) by ncsmtp03.ogw.rr.com (8.12.5/8.12.2) with ESMTP id gASF7siZ010007 for ; Thu, 28 Nov 2002 10:07:54 -0500 (EST) Received: from o7y6b5 ([24.25.90.153]) by mail5.carolina.rr.com with Microsoft SMTPSVC(5.5.1877.757.75); Thu, 28 Nov 2002 10:07:36 -0500 X-Original-Message-ID: <005201c296f0$d55c2b20$1702a8c0@WorkGroup> From: "Ed Anderson" X-Original-To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Coolant loss : More cooling system test stuff. X-Original-Date: Thu, 28 Nov 2002 10:14:23 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Here is my best guess. The molecules of any substance (in which they can freely move) will tend to increase their velocity if they are heated. This increased velocity of individual molecules when integrated over their total number exerts a force on any containment vessel (which we common refer to as "pressure"). As the velocity (heat) of the molecules increases the results is an increase in pressure inside the containment vessel. If this pressure increases pass the capacity of the radiator cap then it will force some liquid into the overflow container. After the engine stops, the coolant cools down and the pressure drops (lower molecule velocity) which if it drops far enough now creates a negative differential pressure inside the coolant system sucking the coolant in the overflow bottle back into the coolant system. Another possible contributor to pressure increase is all liquid has air entrapped between the water molecules so that t when the liquid is heated the air molecules come out of solution (much as you see bubbles in boiling water) and occupy space. Perhaps the water when heated also tends to expand (as its molecules increase their speed with temperature)This generates additional pressure which causes the water to push past the radiator cap pressure release. So there you have it, my 0.02 worth. Perhaps we have someone on the list who really knows what is happening. Ed Anderson ----- Original Message ----- From: "Peter Cowan" To: "Rotary motors in aircraft" Sent: Thursday, November 28, 2002 9:10 AM Subject: [FlyRotary] Re: Coolant loss : More cooling system test stuff. > .Tracy and others, what is the theory behind so much liquid in the external > expansion tank? Thermal expansion of the initial coolant volume doesn't > account for such a large overflow. So is vapor building up inside? If it is > there is no longer a liquid filled system. I don't get it. > Peter > > > >> Homepage: http://www.flyrotary.com/