Fluid Compressibility

talk to a fracker!

As in https://en.wikipedia.org/wiki/Hydraulic_fracturing ?

If so, thank you for the guidance.

exactly

The compressibility factor is for a gas, you idiot. We're talking about liquids here.

Try, please oh, just try to not be so verbally incontinent.

Sheesh!

(To the original poster (OP): This may seem harsh, but you have not been around for all of the previous Legolaz posts. I think your post here was well thought out and well stated. Welcome to CR4!)

..."verbally incontinent". Beautiful!

"Well that might be me your refering too."

Exactly, you are a fracking expert on fluid compression. If you'll pardon mt french there.

(Two Battlestar Galactica series, plus the spin-offs, and they STILL chose that word to represent the technique and industry. Either they had *NO* sense of popular culture since before the 60's, or they knew all too well, and deliberately chose that to brag how they were going to frack us all just to make a little profit.

I wouldn't call myself a fraccing expert by any means. I worked with guys who knew way more than me.

Mostly I just tried to pay attention to the guys doing the technical work above and beyond our own crews jobs and asked questions in the hopes of remembering in at least half of it correctly.

Liquids are compressible to a very slight extent but the change in volume under normal circumstances can be ignored. For example, for an increase of 14.7 psi, water becomes 46 millionths denser. I know of no application that takes into account change in volume of a compressed liquid.

The variation of volume due to temperature change is far more noticeable than the variation due to pressure change at everyday conditions. However, that is not the case near the boiling point at any pressure or at the critical point, around which there is no phase change between liquid and vapour.

If there is a fluid mechanics module in the course, its sampling is recommended.

Here are some valuable resources for you:

MatWeb: Online Materials Information Resource

Bulk Modulus and Fluid Elasticity - Engineering ToolBox

The chart Rixter posted came from ↑

Compressibility of Liquids - HyperPhysics

The internet is an invaluable source of engineering information. Learn to use it wisely and often, then if you still have issues that your instructors can't help you with there are some smart guys here who will try to help.

Yes Sir, the internet has proven quite valuable. The one thing it has taught me thus far is I'm getting ahead of myself.

Maybe some context might help - I'm a Freshman at a community college and this is an introductory course to Machines and how they work... with a small section on hydraulics and pneumatics, barely two pages long and the term 'incompressible' stood out to me and I thought that maybe that isn't always the case but the teacher presents as kind of unapproachable - like he has better things to do than teach us so I thought I'd check out the web and came across this forum... and the Engineering Toolbox site to... but it's still a little over my head... I'm in 098 Math right now; the down side to liking girls and playing football more than doing homework in high school I suppose.

Reading through some of the posts on this site and it looks like you guys are where I'd like to be some day - smart and sarcastic so I joined.

And my apologies for not clarifying my original question better... was just looking for a real world application that would allow me to visualize a system or process that accounts for fluid compressibility in its function and maybe be able to apply that to the end of course project/paper.

I think you're right that you're getting ahead of yourself. You'd do better making sure you understand thoroughly the stuff in the course, before worrying about going beyond it.

I agree with other posters that in practice compressibility of hydraulic fluid (and most other liquids) is negligible.

we certainly know more than your teacher careful about compressing things that resist

Looks like someone learned that lesson the hard way. Many decades ago as the mechanic for a SCCA amateur racing team, after the Saturday testing, the next morning we returned to find that the engine starter could not rotate the engine. As a next step, we removed the spark plugs, unfortunately, one person positioned himself on that side of the engine when I hit the starter.

Lesson learned: If you suspect a head gasket leak, and don't want to be hit in the face by a 1/2 inch stream of water, don't stand facing the spark plug holes when testing for water in a cylinder.

Welcome to the site. Yes, you will find a mix of sarcasm (applied where appropriate), humor to help bring out a chuckle from time to time, and also a lot of really good information from people who enjoy sharing their knowledge. We'll give the best answer we can and hopefully warn the reader when we are not necessarily speaking about our strongest points.

Cheers!

"Yes, you will find a mix of sarcasm (applied where appropriate),"

And where inappropriate, if the result is a bigger laugh.

Be a bit careful about the term "fluid". Some fluids are highly compressible.

Whilst it is commonly used in the context of a liquid, gases are also fluids as are plasmas. Basically anything that can free flow and take the shape of its container is considered to be a fluid, even some of the more viscous stuff that may take time to do that.

"So shines a good deed in a weary world..." to steal a line from Willy Wonka.

You come here with honesty and humility, and above all else, good manners. You are quite welcome here, and you will find many friends and potential mentors as long as you keep an open mind. I myself am a good resource for electronics-related questions, as well as sarcasm and coffee-related humor. I still don't know where the coffee jokes come from; I'm nowhere near the coffee addict I portray on the site, I guess sometimes the Story chooses its Teller, instead of the Teller choosing his Story.

I would also like to give my best regards to your parents and grandparents, for raising you well. Hold on to that sense of humility, it will serve you well when dealing with a technologically incompetent boss, and odds are you WILL run into at least one sometime during your career.

ALL servo-hydraulic systems are designed with the oil (or fluid ) compressibility in mind.

The higher is the frequency the more important are the effects of fluid compressibility.

For instance the own frequency of a hydraulic motor coupled with an inertial element (mass in linear movement or flywheel in a rotating system) depends directly of the entrapped fluid compressibility. This is one of the reasons why so much care is taken for air purge. Other gave you indications about the values of the bulk modulus.

Thank you Sir,

Going to read up on servo hydraulics and would robot arms on car assembly lines, or the video I saw of the iPhone being manufactured be appropriate applications or is their mass too small, or pressure too low to have to account for compressibility?

The elastic flexure of the material, robot arms and actuators would far more significant.

Permanent flexure even more so and possibly career changing.

Any liquid compression deviations, if they even exist, would be buried in the noise.

Keep thinking, enjoy.

The bare word "incompressible" in your text might suggest absolute incompressibility, and you were right to question that. (As Rixter's citation showed.) On the other hand, liquids can mostly be considered as practically or virtually incompressible. Welcome to CR4; I think you will fit in well. Best wishes for success as you enter engineering fields.

Don't worry about personal responses. We're pretty informal here.

Good luck and pursue your dreams.

Welcome to CR4 Zentao, we need more people in this world like you! Hang in there, it will get better as you go along. It's inquisitiveness that makes great engineers. I've found with myself, if I can relate the subject that's being studied to the "working" real world I would get a better grasp of it and remember it easier. Way too many years ago, when I started geometry I had a rough time with it, then I picked up a pool cue stick then the angles and vectors fell in to place. Something as simple as playing pool put things in perspective, "for every action ... there's a reaction"

Because this is a world wide forum, translation is a must And also, there are some pretty sharp women that enjoy this forum, so when your asking a question or what ever, just keep in mind that you'll be addressing them to.

Have fun and come back soon

Dan