I go with that, absolute has very limited meaning in terms of Humidity.
Be careful not to over spec humidity, it will come back to bite you.
Chuck
Charles W. Brummer | 3M Manufacturing Engineer
3M Electronic Solutions Division
3M Canoga Park, 8357 Canoga Ave. | Canoga Park, CA 91304
Office: 818 734 4930
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From: Steven Creswick <[log in to unmask]>
To: <[log in to unmask]>
Date: 03/08/2013 10:35 AM
Subject: Re: [TN] Humidity Measurements: Relative or Absolute
Sent by: TechNet <[log in to unmask]>
Bob,
You are correct. I was partially asleep. Where is Dewey when you need
him
to say that 'everything is relative'?
Going to be pretty tough to measure absolute humidity in a quick and easy
manner.
One item I found suggested avoiding the term "absolute humidity".
Steve C
-----Original Message-----
From: Robert Kondner [mailto:[log in to unmask]]
Sent: Friday, March 08, 2013 12:37 PM
To: 'TechNet E-Mail Forum'; 'Steven Creswick'
Subject: RE: [TN] Humidity Measurements: Relative or Absolute
Steve,
Relative Humidity: http://en.wikipedia.org/wiki/Relative_humidity
http://www.youtube.com/watch?v=CL5cgXwKUXc
If the absolute humidity is high (even 30%) but the temperature is also
high, I think the humidity indicators will show low humidity exposure.
I think that relative humidity is crucial to component water absorption
or
drying.
But I wonder if package cracking doing to expansion of gases entrapped in
the package material (plastic) is a function of the absolute vapor content
in that material.
Bob K.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Creswick
Sent: Friday, March 08, 2013 11:35 AM
To: [log in to unmask]
Subject: Re: [TN] Humidity Measurements: Relative or Absolute
Bob,
I have always considered them to be absolute. If relative - relative to
what?
Do the cardboard indicators provide a temp range for which they are valid?
Steve C
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Friday, March 08, 2013 11:24 AM
To: [log in to unmask]
Subject: [TN] Humidity Measurements: Relative or Absolute
Hi,
As I start looking at humidity measurement devices I started to wonder if
IPC humidity numbers are Relative or Absolute? Does anyone know off hand.
I
need to go buy some specs.
I would have thought Absolute but the cardboard indicators are temperature
sensitive as are the desiccant drying systems in dry cabinets.
If the temperature is high, say > 100C then a part will "Bake Out"
regardless of the absolut humidity, is that right?
Bob K.
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