So, reiterating what others are saying in reply to my email: The HD37AB1347 device with the HP474AC probe is designed to measure air with 0% to 100% humidity. It is not designed to measure pure water vapor with tiny liquid droplets (including zero liquid droplets) in it.
It isn't even close - there is no way that measuring Relative Humidity will give you the quality (mass fraction of vapor) of the steam. They might have somehow used the device to measure quality of the steam in a non-standard non-typical manner but I can't think of a way they might have done that. The capacitance as measuared by the probe would be vastly different when measuring air saturated at 100% compared to pure water vapor (with or without tiny liquid droplets). If someone is able to find out what the vapor looked like when it left the hose then let us know. Was it transparent and high velocity? 12 kW should make a serious sized jet of water vapor that should condense into whitish cloud some distance from the hose. here again, are the specifications on that probe: http://tinyurl.com/45rwsvh HP474AC Relative Humiditiy Probe specifications: 5% to 98% RH @ -40C to 150 C +/- 2.5% (5%...95%RH) +/-3.5%(95%...99%RH) Temp +/-0.3C On Sun, Jan 23, 2011 at 12:44 AM, <mix...@bigpond.com> wrote: > In reply to Harry Veeder's message of Sat, 22 Jan 2011 19:36:13 -0800 > (PST): > Hi, > > > > > > > >Robin van Spaandonk wrote: > > > >>Consider that droplets can't form unless the RH is 100%. Anything less > >than > >>that > >>and no droplets form. > >>In short if they measure an RH < 100% then the steam must be dry. > > > >So, if the RH is below 100% you can surmise the steam is fully dry (0% > wet)but > >if the RH is above 100% the RH meter is uselss for telling you > > > >how much less dry (or more wet) the steam is ? > >Harry > > > You can't have RH > 100%, but it could be exactly 100%, in which case you > are > indeed no wiser. > > Regards, > > Robin van Spaandonk > > http://rvanspaa.freehostia.com/Project.html > >
