Actually, the sensor I used was a differential sensor. One side was the outside (of the room) pressure and the other was the room pressure, which has to be 100 Pa below the outside one. Mauricio Jancic Janso Desarrollos Microchip Consultant Program Member (54) 11-4542-3519 info@janso.com.ar www.janso.com.ar >>-----Original Message----- >>From: pic microcontroller discussion list >>[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Michael Rigby-Jones >>Sent: Friday, August 20, 2004 11:54 AM >>To: PICLIST@MITVMA.MIT.EDU >>Subject: Re: [EE]: Flow sensing >> >>>-----Original Message----- >>>From: pic microcontroller discussion list >>>[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Mauricio Jancic >>>Sent: 20 August 2004 13:41 >>>To: PICLIST@MITVMA.MIT.EDU >>>Subject: Re: [EE]: Flow sensing >>> >>> >>>Ok, can I ask you something? If, you make a small hole to >>the pipe and >>>put a pressure sensor, it must work. There are sensors with >>precision >>>down to 10 Pa, (that I used, there must be lower). 10 Pa is >>close to a >>>blow if I recall that sensor would detect a blow directed to >>its input >>>from a distance of 2 meters.... So, I must detect the pressure >>>increasing when the flow is stopped but the pump still runs. >>> >>> When you detect the flow increasing, you shutdown >>the pump. And >>>the "high" pressure will remain stable (you might need a non return >>>valve after the pump) until the flow is allowed again by the laser... >>> >>> Now, why this wouldn't work? (just wondering...) :) >> >>A better way is to use two pressure sensors, one either side >>of a fixed restriction in the pipe. You can now measure the >>difference between the two sensors to get pressure drop (and >>hence flow) without having to worry about what the static >>pressure is (which may vary). >> >>Regards >> >>Mike >> >>============================================================== >>========= >>This e-mail is intended for the person it is addressed to >>only. The information contained in it may be confidential >>and/or protected by law. If you are not the intended >>recipient of this message, you must not make any use of this >>information, or copy or show it to any person. Please contact >>us immediately to tell us that you have received this e-mail, >>and return the original to us. Any use, forwarding, printing >>or copying of this message is strictly prohibited. >>No part of this message can be considered a request for goods >>or services. >>============================================================== >>========= >> >>-- >>http://www.piclist.com hint: The list server can filter out >>subtopics (like ads or off topics) for you. See >>http://www.piclist.com/#topics >> -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics