and he notes - In order to compress water from 30 ft to 29 ft 8.4 inches (the water in your 30 ft pipe example) it would have to be subjected to tens of thousands of atmospheres (roughly 15 psi per atmosphere). Water compresses at .0000046% for each increment of atmospheric pressure. The main reason water is not used in most hydraulic lines is variations in temperature (mainly freezing) and the corrosive effect on metallic parts. So you would really have to have a heavy foot to compress water to any negligible degree.
However, there are practical applications as seen on this site: http://www.hydraulicspneumatics.com/200/TechZone/HydraulicFluids/Article/True/6452/TechZone-HydraulicFluids At Sandia Laboratories water has been converted to a form of ice "VII" (not to be confused with the "Ice Nine" as used in Vonnegut's SC-Fi book "Cat's Cradle") by subjecting it to millions of psi. Unlike the more familiar ice used in drinks, this stuff does not expand the usual 4% but remains the same volume. But don't drop any in your Koolaid as it is hotter than steam! When water tunes to steam it expands 1200 times its volume in a free space such as a tea kettle. But when it is enclosed in a locomotive or power plant boiler, it will remain as a liquid when boiler pressure is equalized and will continue to evaporate as steam is used to power a turbine or in the case of a locomotive, the cylinders. When standing for any length of time (and especially on cold days) steam admitted to the cylinders will quickly condense and with no place to go, will be pressed against the cylinder heads as the pistons begin to move. To keep from blowing the cylinder head off, (and there was many an engineer who did just that) blow off cocks were installed on either end of the cylinder and the locomotive engineer would pull a lever to engage them resulting in a cloud of 'steam' when the engine started moving. But it is not high temperature steam as one would expect as it cools quickly on expansion. Once the cylinders have warmed, the cocks are closed and the cylinders exhaust through the blast nozzle. My home town was on the main line from Boston to Concord, NH and a dozen or more trains stopped there daily. I remember (as a kid) standing near the locomotive on a bitter cold winter's day just to get the effect. I got a nice coat of water that quickly froze - a trick one needed to pull only once. The engineer got a kick out of it! I never did it again but I do have dozens of photos of B&M steam clearing the cylinders. Always a pretty sight. I wonder of it would be possible to rig a smoke unit to simulate the effect in a model... Raleigh in steamy Maine At 10:03 AM 8/19/2008, Ed Kozlowsky wrote: >OK, I'm going to say one more thing on the matter and then drop >it. The difference of compressibility between water and steam is an >order of magnitude, so naturally water would, for practical >purposes, be considered incompressible in that context. But, that >was not the context of the original statement. That had to do with >cushioning freight car loads. Let me give an example relative to >that. It's not inconceivable that a standard size large car or >truck would have 30 feet of brake line. A tremendous amount of >pressure is applied to the brake fluid given the magnification of >power brakes. If the fluid was water with an approximately 1% of >compression, the water in the line would compress 3.6 inches, and >that my freinds is one heck of a lot of brake pedal movement. It's >enough movement to act as an effective "cushion" or spring, which is >what the discussion started with. Not steam chests. > >Ed Kozlowsky >Sanford, Maine > >--- On Tue, 8/19/08, Rance and Bente ><<mailto:velapoldi%40gmail.com>[EMAIL PROTECTED]> wrote: > >From: Rance and Bente <<mailto:velapoldi%40gmail.com>[EMAIL PROTECTED]> >Subject: Re: {S-Scale List} Re: water compresses >To: <mailto:S-Scale%40yahoogroups.com>[email protected] >Date: Tuesday, August 19, 2008, 9:34 AM > >Hi all: >As we know, all liquids have different compressibility factors, Z. I >think Ed K said (rightly so) it wasn't worth arguing about - we don't >really need to be concerned about the compressibilities of liquids at >standard temperature and pressure. However, the compressibility factor, >which can be critical in engineering measurements/ predictions, are >definitely important when T and P increase. Anyhow, unless we are doing >live steam, enjoy modeling and don't worry too much about >compressibility (unless one is a worrier - then google it or get some >engineering/ physics books on changes of state)! >regards, >Rance Velapoldi (Tranby, Norway) > >Robert Nicholson wrote: > > > > That's why diesel engines have flashcocks, too. Water in the > > compression chamber can destroy a diesel engine. > > > > In fact, that's the very foundation of hydraulics - fluids do not > > compress under pressure > > > > Bob Nicholson > > > > --- In [EMAIL PROTECTED] .com <mailto:S-Scale% 40yahoogroups. com>, > > [EMAIL PROTECTED] wrote: > > > > > > > > > In a message dated 8/18/2008 11:52:21 AM Eastern Standard Time, > > > soldado7264@ ... writes: > > > > > > I don't want to get off topic, but actually water compresses quite > > nicely. > > > > > > Any steam engineman would disagree---reason for steamcocks on > > cylinders of > > > locomotives. Water DOES NOT compress, will destroy cylinders, hence > > the drains. > > > When I ran "Little Toot", always left the station with the cocks open, > > > closing them on the first turn. > > > Jim Lyle > > > > > > > > > > > > > Recent Activity > > > > * > > 1 > > New Photos > > <<http://groups.>http://groups. yahoo.com/ group/S-Scale/ > spnew;_ylc= X3oDMTJlNnBua3Nn BF9TAzk3MzU5NzE0 BGdycElkAzI1MjE5 > MARncnBzcElkAzE3 MDY1MzM4MTgEc2Vj A3Z0bARzbGsDdnBo b3QEc3RpbWUDMTIx > OTA4Nzg0MQ- -> > > > > Visit Your Group > > <<http://groups.>http://groups. yahoo.com/ group/S-Scale; > _ylc=X3oDMTJkY2M 2ZWUzBF9TAzk3MzU 5NzE0BGdycElkAzI 1MjE5MARncnBzcEl > kAzE3MDY1MzM4MTg Ec2VjA3Z0bARzbGs DdmdocARzdGltZQM xMjE5MDg3ODQx> > > > > Yahoo! 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