In the medical field, I would think that air in the lines would do more than "affect the readings",... it could kill the patient.
Isn't that why doctors always fill the syringe and then point the needle up and squirt out some liquid to ensure that all the air is out.
Air bubbles in the blood stream can kill.
Air bubbles in the oil are not so deadly.
Jim Maher
David Staten <Dastaten@earthlink.net> wrote:
snip
I was basing my question about the purge bit based on my healthcare experience... In the ICU and some OR settings catheters/lines are directly placed into arteries, brain spaces, large veins and pressure readings are transduced in order to manage treatment. Air in the lines affects the readings.. but then I realized the air affects the CHANGES of pulsatile flow.. it dampens it... like the pressure wave with your heartbeat. In a constant-pressure situation (or at least "non-pulsatile" pressures.. in which the character of the pressure waveforms dont matter) I guess you are right.. pressure is pressure.. and the reason we are measuring it shouldnt matter on the presence or absense of air.
Dave
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