REFLECTOR:RE:weak gas struts

[Alex Balic]

The movement you see when you do this is a result of the small amount of air
foreword of the plunger (yes it is small, but it is there- if you fill the
syringe up with oil, make sure all of the air is out, then repeat the
experiment, it will not move.  Further, this is one reason that it is very
rare to use water in a hydraulic system, because it will absorb gas under
pressure like soda does with CO2- the hydraulic oil will for practical
purposes will not absorb gas/air (although if it is contaminated with water,
then the water will) Water also has a relatively high vapor pressure, and I
would bet that if the Velocity system was contaminated, then the water would
vaporize and create a bubble in the system under reduced pressure.

-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
Behalf Of Richard@Riley.net
Sent: Thursday, January 01, 2004 5:03 PM
To: reflector@tvbf.org
Subject: RE: REFLECTOR:RE:weak gas struts


If you pull hard enough, even if the vapor pressure was zero, it would move.

Simple experiment.  Take a syringe, no needle.  Plug the end with your
thumb.  Pull out the plunger.  It takes some force, probably 1-5 lb or so
(depending on the diameter of the plunger) but it WILL pull.  Inside is a
near vacuum.  Let go and it will snap in.  The vapor pressure of your thumb
isn't significant.

The force you have to apply is the area of the face of the plunger times
one atmosphere.  If the plunger is 1/2" in diameter, that force is 2.88 lbs.

If there is vapor pressure in the working fluid, the force is the area
times the atmospheric pressure minus vapor pressure.




At 06:36 PM 1/1/04 -0500, Chuck Jensen wrote:
>Are you sure hydraulic will form a bubble under vacuum (likely to be
>encountered in this instance) given the vapor pressure of the hydraulic
>fluid compared to water?
>
>Chuck Jensen
>
>
>-----Original Message-----
>From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
>Behalf Of steve korney
>Sent: Sunday, December 28, 2003 1:21 AM
>To: reflector@tvbf.org
>Subject: RE: REFLECTOR:RE:weak gas struts
>
>
>It's like cavitations...That's how a boat propeller makes bubbles under
>water...
>
>
>Best... Steve
>
>
>---------------------------------------------------------------------------
-
>-------------------------------
>
>
>Steve,
>How does it produce this bubble? In my experience, you can lock a hydraulic
>cylinder from either side by blocking either the intake or exhaust port.
>
>_________________________________________________________________
>Tired of slow downloads? Compare online deals from your local high-speed
>providers now.  https://broadband.msn.com
>
>_______________________________________________
>To change your email address, visit
>http://www.tvbf.org/mailman/listinfo/reflector
>
>Visit the gallery!  www.tvbf.org/gallery
>user:pw = tvbf:jamaicangoose
>Check new archives: www.tvbf.org/pipermail
>Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>_______________________________________________
>To change your email address, visit
>http://www.tvbf.org/mailman/listinfo/reflector
>
>Visit the gallery!  www.tvbf.org/gallery
>user:pw = tvbf:jamaicangoose
>Check new archives: www.tvbf.org/pipermail
>Check old archives: http://www.tvbf.org/archives/velocity/maillist.html

_______________________________________________
To change your email address, visit
http://www.tvbf.org/mailman/listinfo/reflector

Visit the gallery!  www.tvbf.org/gallery
user:pw = tvbf:jamaicangoose
Check new archives: www.tvbf.org/pipermail
Check old archives: http://www.tvbf.org/archives/velocity/maillist.html