Hi Charles, My experience has been that a "low-cost" pressure sensor approaching 1" w.c. full scale will cost around $100 or so. The Siemens 590 series looks to be intended for HVAC/Building Automation. The 590 series go as low as 0.25" w.c. but they list at $356! Ouch! Not low cost! and the specs are not as good as a Honeywell 160PC. Maybe Siemens has other stuff too - I don't know. We use a lot of the Honeywell 160PC series in industrial products and also in in-house test equipment. The unit we use the most IIRC is a +/- 2.5" unit (we use about 1000 of these per year). I'm not sure if Honeywell has a unit that goes down to to 1" full scale. They have several different series to choose from. 1" w.c. is not much pressure - if you *really* want (or need) a 1" sensor you are probably going to pay for it. You already found a unit at Digikey for $88 - that doesn't sound bad to me. We usually purchase the Honeywell 160PC in lots of 30-50 pcs for about $60 ea. Again, $88 for 1 pc doesn't sound too bad. The All Sensors units from DigiKey look very similar to what Data Instruments used to sell as the DRAL5 series which we used to use (I think Data Instruments was purchased by Honeywell). We have a 1" full scale Data Instruments unit somewhere around here, but I haven't seen it for a while. I think we paid about $100 for it. Depending on what you are doing you *may* be able to use a sensor with a higher full scale range and amplify the signal and do some averaging in firmware. We do this with a +/-2.5" unit and get 0.001" resolution. But EVERYTHING affects this setup. If someone opens a nearby door we can sense the air pressure change. If someone walks across the roof we can sense the air pressure change. If somebody walks through the lab at a brisk pace we can sense the air pressure change. On a windy day the readings jump all over. If the A/C or heat comes on during a test you can start over. My nickname for the setup is the "mosquito fart detector". Good luck searching. Maybe there is a deal out there that we missed! -- Mark > -----Original Message----- > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf > Of Charles Linquist > Sent: Wednesday, August 03, 2005 1:24 AM > To: Microcontroller discussion list - Public. > Subject: Re: [EE] Re: Pressure sensor > > > I appreciate the feedback, but none of the manufacturers mentioned have > sensors that are sensitive enough. I need to measure 1" of water full > scale = .036psi. > > All Sensors has such devices, but as I mentioned, they cost $88 > > > Charles Linquist > > > > PicDude wrote: > > Also check Honeywell (which also now includes Sensym) and Freescale for > > low-cost sensors. > > > > http://content.honeywell.com/sensing/products/pressureforceflow/ > > http://www.freescale.com > > > > Cheers, > > -Neil. > > > > > > On Tuesday 02 August 2005 01:58 pm, Vasile Surducan scribbled: > > > >>Siemens have a full range of pressure sensors, single and differential > >>inputs at about 30-40 USD. Nice metalic package. > >> > >>Vasile > >> > >>On 7/31/05, Charles Linquist wrote: > >> > >>>I'm looking for a differential air pressure sensor that can measure > >>>1" of H20 full-scale. > >>> > >>>Preferably, I would like units that were amplified, although I could > >>>deal with mv output sensors if that was the only option. > >>> > >>>The only ones I can find are from All Sensors Inc, and cost $88 each > >>>(from Digi-Key). Does anyone know of any cheaper source of small > >>>low-pressure sensors? > >>> > >>> > >>>Charles Linquist > >>> > >>>-- > >>>http://www.piclist.com PIC/SX FAQ & list archive > >>>View/change your membership options at > >>>http://mailman.mit.edu/mailman/listinfo/piclist > > > > > > > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist