On 01/20/2011 10:08 AM, Jed Rothwell wrote: > Pierre Carbonnelle wrote to me: > >> Macy's report talks of a Delta OHM # HD37AB1347 Indoor Air >> Quality Monitor, whose specifications are here >> <http://www.deltaohm.com/ver2010/uk/st_airQ.php?str=HD37AB1347>. >> >> Could this invalidate the dryness measurement ? > > Maybe. I don't know enough about the instrument to judge. Maybe the RH > function works even though it is out of the recommended range. I'll > see if I can ask the guy who used it.
I'm still confused over this. How do you use a relative humidity meter to measure dryness of steam? Pure steam at 100 C should have a RH of 100%, since its vapor pressure at that temperature is 1 atmosphere. At 101 C the RH will be marginally lower, but maybe not enough of a difference to detect with this instrument. How would entrained water droplets change that? Or is the argument that 101 C steam is sufficiently superheated that it can't carry liquid water along? That doesn't sound right, though; it doesn't seem like it would be hot enough. > > Even if the steam is wet, the conclusion stands, but they should have > used the recommended instrument. > > It looks like the HP474ARC would be a better choice. > > - Jed >
