Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Harry Veeder]

- Original Message 
> From: Stephen A. Lawrence 
> To: vortex-l@eskimo.com
> Sent: Sun, January 23, 2011 10:48:48 PM
> Subject: Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality
> 
> 
> 
> On 01/23/2011 10:32 PM, Harry Veeder wrote:
> >> Stephen A.  Lawrence  wrote:
> >>
> >>  No, I don't think so.   The  stuff pumped out of the supply tank, and into
> >> the reactor,  is 100% water; air  comes into the supply tank at the top
> >> and  displaces the water in the tank as  it's pumped out.
> >> 
> > Well you seem confident so I'll take your word for  it.
> >  
> 
> That's the kind of reasoning that resulted in all  those marines marching
> into a swamp full of quicksand a few years  back...
> 
>

Perhaps the RH sensor can't tell the difference between dry steam (superheated 
water vapour)  and dry air. In other words unless the steam contains some 
ordinary wet vapour the RH reading should be %0.

Harry

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Horace Heffner]

Good grief Jed! You have to keep straight the difference between mass  
and volume!


Your reference clearly states "If the water content of the steam is  
5% by mass, then the steam is said to be 95% dry and has a dryness  
fraction of 0.95."


By my table, 95% steam has way less than 0.1% water by volume.  This  
would barely make any difference in capacitance.


Also note that your refer to 5 bar steam.  That has 5 times the mass  
in vapor as atmospheric steam.  I'd do some calculations regarding  
this, but just don't have time.  I don't even have time to read all  
the vortex posts right now.


Best regards,

Horace Heffner
http://www.mtaonline.net/~hheffner/


On Jan 23, 2011, at 6:23 AM, Jed Rothwell wrote:


Horace Heffner  wrote:

We can thus see from this table that if 1 percent by volume of the  
steam is entrained water micro-droplets, easily not seen in tubing  
or exhaust ports, that only 5.6 percent of the heat of vaporization  
is required to produce that mixture.


I do not think so. See:

http://www.engineeringtoolbox.com/wet-steam-quality-d_426.html

QUOTE:

Example - Enthalpy and Specific Volume of Wet Steam
Steam at pressure 5 bar gauge has a dryness fraction of 0.95.

Total enthalpy can be expressed as:


ht = (2085 kJ/kg) 0.95 + (1 - 0.95) (670.4 kJ/kg)

= 2,014 kJ/kg

Specific volume can be expressed as:

v = (0.315 m3/kg) 0.95

= 0.299 m3/kg



That says 2,014 kJ/kg (not 2.0). Almost as much enthalpy as dry steam.

Anyway, we can test this at home. Get something like an electric  
frying pan, rated at 1.5 kW. Boil some water in. That produces wet  
steam; you can see the vapor condensing about the pan. The power is  
half of the 2.97 kW Heffner estimates the Rossi device may be  
producing (assuming 1% wet steam). So, it should be able to boil  
away the water in about twice the time it takes Rossi. Take a  
gallon of water (3.8 L) starting at 15 deg C, and see if you can  
boil away the entire gallon in 26 minutes.


- Jed

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Stephen A. Lawrence]

On 01/23/2011 10:32 PM, Harry Veeder wrote:
>> Stephen A. Lawrence  wrote:
>>
>>  No, I don't think so.  The  stuff pumped out of the supply tank, and into
>> the reactor, is 100% water; air  comes into the supply tank at the top
>> and displaces the water in the tank as  it's pumped out.
>> 
> Well you seem confident so I'll take your word for it.
>   

That's the kind of reasoning that resulted in all those marines marching
into a swamp full of quicksand a few years back...

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Harry Veeder]

- Original Message 
> From: Stephen A. Lawrence 
> To: vortex-l@eskimo.com
> Sent: Sun, January 23, 2011 9:58:57 PM
> Subject: Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality
> 
> 
> 
> On 01/23/2011 09:49 PM, Harry Veeder wrote:
> > Stephen A. Lawrence  wrote:
> >
> >  
> >> If it's pure steam (no entrained air)  at 100 C, then  the RH must be
> >> 100%, a priori, since the vapor  pressure of water at 100 C is  1
> >> atmosphere.  
> >>
> > I think it is mixed with air, otherwise the  water pump would have to work 
>harder 
>
> > and harder as a vacuum is created  in the water supply tank.
> >  
> 
> No, I don't think so.  The  stuff pumped out of the supply tank, and into
> the reactor, is 100% water; air  comes into the supply tank at the top
> and displaces the water in the tank as  it's pumped out.

Well you seem confident so I'll take your word for it.

Harry

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Stephen A. Lawrence]

On 01/23/2011 09:49 PM, Harry Veeder wrote:
> Stephen A. Lawrence wrote:
>
>   
>> If it's pure steam (no entrained air) at 100 C, then  the RH must be
>> 100%, a priori, since the vapor pressure of water at 100 C is  1
>> atmosphere.  
>> 
> I think it is mixed with air, otherwise the water pump would have to work 
> harder 
> and harder as a vacuum is created in the water supply tank.
>   

No, I don't think so.  The stuff pumped out of the supply tank, and into
the reactor, is 100% water; air comes into the supply tank at the top
and displaces the water in the tank as it's pumped out.

The water will have some air dissolved in it, come to think of it.  I
doubt it's a significant fraction, however, and I doubt it's more than a
tiny fraction of the gas coming out.


> Harry
>   

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Harry Veeder]

Stephen A. Lawrence wrote:


> 
> If it's pure steam (no entrained air) at 100 C, then  the RH must be
> 100%, a priori, since the vapor pressure of water at 100 C is  1
> atmosphere.  

I think it is mixed with air, otherwise the water pump would have to work 
harder 
and harder as a vacuum is created in the water supply tank.

Harry


> And at 101 C, pure steam will have a RH very close to  100%,
> since it's only 1 degree above its dew point.  So it's not clear  to me
> what a RH meter is going to tell you that you don't already  know,
> particularly given that the meter is +/- 3.5 % at 99% RH.  (That  assumes
> they're in Bologna, which is only 54 meters above sea level,  according
> to some website or other.  If they were up in the mountains,  the RH of
> 101 C steam would be lower, since the boiling point of water would  be
> lower, and we might expect 101 C steam to be drier, in  general.)



> Furthermore, I'm not sure it's correct to say <100% RH  implies there
> can't be entrained droplets.  The drops don't form in the  steam, they're
> blown/broken/pulverized off the surface of the water and  carried off
> with the steam.  They can be carried off with a stream of  air at < 100%
> RH just as easily as they can be carried off by a stream of  pure steam. 
> If it's <100% RH at the point where you measure it, then some  way
> downstream the steam may be expected to cool as the droplets  evaporate,
> which means the temperature reading your probe is reporting won't  mean
> what you think it does.
>

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Jed Rothwell]

Horace Heffner  wrote:


> We can thus see from this table that if 1 percent by volume of the steam is
> entrained water micro-droplets, easily not seen in tubing or exhaust ports,
> that only 5.6 percent of the heat of vaporization is required to produce
> that mixture.
>

I do not think so. See:

http://www.engineeringtoolbox.com/wet-steam-quality-d_426.html

QUOTE:

Example - Enthalpy and Specific Volume of Wet Steam

Steam at pressure  *5
bar gauge* has a dryness fraction of *0.95*.

Total enthalpy can be expressed as:


*ht** = (2085 kJ/kg) 0.95 + (1 - 0.95) (670.4 kJ/kg)*

*= 2,014 kJ/kg*

Specific volume can be expressed as:

*v** = (0.315 m3/kg) 0.95*

*= 0.299 m3/kg*


That says 2,014 kJ/kg (not 2.0). Almost as much enthalpy as dry steam.

Anyway, we can test this at home. Get something like an electric frying pan,
rated at 1.5 kW. Boil some water in. That produces wet steam; you can see
the vapor condensing about the pan. The power is half of the 2.97 kW Heffner
estimates the Rossi device may be producing (assuming 1% wet steam). So, it
should be able to boil away the water in about twice the time it takes
Rossi. Take a gallon of water (3.8 L) starting at 15 deg C, and see if you
can boil away the entire gallon in 26 minutes.

- Jed

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Stephen A. Lawrence]

On 01/23/2011 01:12 AM, Horace Heffner wrote:
>
> This whole issue /[of steam quality measurements]/ may be of academic
> interest only...

Only if another demonstration is done with no input (closed loop).

Otherwise it's still extremely interesting because, if this measurement
was botched as badly as it seems, we really need to ask /why/.  These
guys are experts in calorimetry; they /must/ know how to tell, for real,
if steam is dry or not, and they /must/ know what the limitations of
using a RH meter to measure steam quality are.  And surely they know how
important the question of its dryness is.

This is almost like they just went through the motions of measuring the
quality of the steam, even though they must have known the measurement
wouldn't tell them anything.  It seems like they provided the appearance
of making a measurement, without really doing it.

So, why would they do that?

RE: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Mark Iverson]

In order to make any accurate assessment of the dryness of the steam, wouldn't 
one have to measure
it as close to the reactor as possible?  Could there be some condensation on 
the inside walls of the
tube and the steam picking up liquid water from that?  Do we know how far from 
the reactor they made
the measurements?

-Mark


-Original Message-
From: mix...@bigpond.com [mailto:mix...@bigpond.com] 
Sent: Saturday, January 22, 2011 9:23 PM
To: vortex-l@eskimo.com
Subject: Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

In reply to  Stephen A. Lawrence's message of Sat, 22 Jan 2011 23:05:10 -0500:
Hi,
[snip]
>If it's pure steam (no entrained air) at 100 C, then the RH must be 
>100%, a priori, since the vapor pressure of water at 100 C is 1 
>atmosphere.

True, but they are likely to have measured somewhere past the end of the tube, 
so I suspect there
sill be at least some entrained air.

>And at 101 C, pure steam will have a RH very close to 100%, since it's 
>only 1 degree above its dew point.  So it's not clear to me what a RH 
>meter is going to tell you that you don't already know, particularly 
>given that the meter is +/- 3.5 % at 99% RH.

Also true, it may not be the best option for task at hand.

>(That assumes
>they're in Bologna, which is only 54 meters above sea level, according 
>to some website or other.  If they were up in the mountains, the RH of
>101 C steam would be lower, since the boiling point of water would be 
>lower, and we might expect 101 C steam to be drier, in general.)
>
>Furthermore, I'm not sure it's correct to say <100% RH implies there 
>can't be entrained droplets.  The drops don't form in the steam, 
>they're blown/broken/pulverized off the surface of the water and 
>carried off with the steam.  They can be carried off with a stream of 
>air at < 100% RH just as easily as they can be carried off by a stream of pure 
>steam.

True if it's pure steam. However if there is some entrained air (after exiting 
the outlet tube),
then any droplets that may have been in the steam will evaporate and raise the 
RH of the air to
100%, i.e. until it is saturated, once again resulting in 100% RH.
 
>If it's <100% RH at the point where you measure it, then some way 
>downstream the steam may be expected to cool as the droplets evaporate, 
>which means the temperature reading your probe is reporting won't mean 
>what you think it does.

What happens downstream is irrelevant unless you are taking measurements there 
and relying on them.
Regards,

Robin van Spaandonk

http://rvanspaa.freehostia.com/Project.html

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Jeff Driscoll]

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,  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
>
>

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Horace Heffner]

On Jan 22, 2011, at 5:24 PM, Jeff Driscoll wrote:

Rossi used this electronic device for electronic measurement (as  
was reported) - model  HD37AB1347.   Relative Humidity probe model  
HP474AC was attached to it.
Page three of this link (thanks to Horace) shows details of that  
probe connected to the electronic device.  HP474AC has the  
following specifications:

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
This probe does not measure the amount of liquid water droplets in  
the "steam" (ie. mass fraction of water vapor to to total water).   
It measures Relative Humidity (Relative Humidity measures how  
saturated the air is for a given temperature).
What we want is a a device that measures "quality" of the steam.   
For reference, 100% quality = 100% vapor.

How did they confirm that the water vapor was truly vapor?


Yes, good question.

I believe the HP474AC probe actually measures the capacitance of the  
air, and converts that to relative humidity.  The more the  
capacitance,  the more water in the air, by volume.  Another  
important thing is heat content is carried  in proportion to mass,  
not volume.  I have appended the computations I posted earlier  
showing the huge proportion of mass that is contributed by a small  
volume of liquid, and that estimates of the heat flow from the device  
can be off by 96%, i.e only 4% of the estimated heat value due to  
vaporization,  if only 1.4% of the volume flow is liquid water  
droplets.  Therefore a very small error, less than 1%, in measuring  
capacitance can produced huge errors in calculated heat flow.  The  
stated error of the probe is +-3.5% where it counts, at 99% water  
content.


It is also notable the meter/probe requires calibration:

http://tinyurl.com/4z5985v

Most important is the fact the probe is designed to detect the  
percent of water vapor in air, not percent of water microdrops in  
pure steam.  Pure vapor should have more capacitance than 100% humid  
air, and be way beyond the meter's measuring limits.  Adding water  
droplet should push the capacitance even higher.  Once the meter is  
maxed,  the question arises: can extra water droplets make any  
difference to an already maxed out 100% reading?  The +-3.5% error  
could thus actually be irrelevant.


This whole issue may be of academic interest only.  Even if all the  
heat flow due to vaporization is negated, the COP is still over  
unity, assuming the  water is not heated much above 13 °C by ambient  
conditions before entering the device.   Further, if the device can  
run without energy input at all, then none of this matters, provided  
the total energy to start up the device is way less than the device  
produces.  This would clearly be the case if the device can run 6  
months as stated.


Here again is my analysis showing the importance of the huge  
difference in mass vs volume ratios:


From:

http://en.wikipedia.org/wiki/Water_(properties)

http://en.wikipedia.org/wiki/Specific_heat_capacity

http://en.wikipedia.org/wiki/H2o

http://hypertextbook.com/facts/2007/DmitriyGekhman.shtml


The following approximate values for water can be used from the above  
refs:


Liquid Density: 1000 kg/m^3 = 1 gm/cm^3

Heat of vaporization: 40.6 kJ/mol = 2260 J/gm

Heat capacity:  4.2 J/(gm K)

Molar mass: 18 gm/mol

Density of steam at 100 C and 760 torr: 0.6 kg/m^3 = 0.0006 gm/cm^3


Now to examine the importance of mass flow vs volume flow  
measurements for the steam.


If x is the liquid portion by volume, then x/((x+(1-x)*0.0006)) is  
the portion by mass. This gives the following table:


Liquid LiquidGas
PortionPortion   Portion
by Volume  by Mass   by Mass
-  ---   ---
0.000  0. 100.00
0.001  0.6252 0.3747
0.002  0.7695 0.2304
0.003  0.8337 0.1662
0.004  0.8700 0.1299
0.005  0.8933 0.1066
0.006  0.9095 0.0904
0.007  0.9215 0.0784
0.008  0.9307 0.0692
0.009  0.9380 0.0619
0.010  0.9439 0.0560
0.011  0.9488 0.0511
0.012  0.9529 0.0470
0.013  0.9564 0.0435
0.014  0.9594 0.0405

We can thus see from this table that if 1 percent by volume of the  
steam is entrained water micro-droplets, easily not seen in tubing or  
exhaust ports, that only 5.6 percent of the heat of vaporization is  
required to produce that mixture.



Rough calculations based on Rossi specifics:

Suppose for the Rossi experiment the mass flow of a system is 292 ml/ 
min, or 4.9 gm/s, the inlet temperature 13 °C.


The delta T for water heating is 100 °C - 13 °C = 87 °C = 87 K.

If the output gas is 100% gas, we have the heat flow P_liq given by:

   P_liq = (4.9 gm/s)*(87 K)*(4.2 J/(gm K))= 1790 J/s = 1.79 kW

and the heat flow H_gas for vaporization given by:

   P_gas = (4.9 gm/s)*(2260 J/gm) = 11.1 kW

for a

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[mixent]

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

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[mixent]

In reply to  Stephen A. Lawrence's message of Sat, 22 Jan 2011 23:05:10 -0500:
Hi,
[snip]
>If it's pure steam (no entrained air) at 100 C, then the RH must be
>100%, a priori, since the vapor pressure of water at 100 C is 1
>atmosphere.  

True, but they are likely to have measured somewhere past the end of the tube,
so I suspect there sill be at least some entrained air.

>And at 101 C, pure steam will have a RH very close to 100%,
>since it's only 1 degree above its dew point.  So it's not clear to me
>what a RH meter is going to tell you that you don't already know,
>particularly given that the meter is +/- 3.5 % at 99% RH.  

Also true, it may not be the best option for task at hand.

>(That assumes
>they're in Bologna, which is only 54 meters above sea level, according
>to some website or other.  If they were up in the mountains, the RH of
>101 C steam would be lower, since the boiling point of water would be
>lower, and we might expect 101 C steam to be drier, in general.)
>
>Furthermore, I'm not sure it's correct to say <100% RH implies there
>can't be entrained droplets.  The drops don't form in the steam, they're
>blown/broken/pulverized off the surface of the water and carried off
>with the steam.  They can be carried off with a stream of air at < 100%
>RH just as easily as they can be carried off by a stream of pure steam.

True if it's pure steam. However if there is some entrained air (after exiting
the outlet tube), then any droplets that may have been in the steam will
evaporate and raise the RH of the air to 100%, i.e. until it is saturated, once
again resulting in 100% RH.
 
>If it's <100% RH at the point where you measure it, then some way
>downstream the steam may be expected to cool as the droplets evaporate,
>which means the temperature reading your probe is reporting won't mean
>what you think it does.

What happens downstream is irrelevant unless you are taking measurements there
and relying on them.
Regards,

Robin van Spaandonk

http://rvanspaa.freehostia.com/Project.html

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Stephen A. Lawrence]

On 01/22/2011 10:13 PM, mix...@bigpond.com wrote:
> In reply to  Jeff Driscoll's message of Sat, 22 Jan 2011 21:24:36 -0500:
> Hi,
> [snip]
>   
>> This probe does not measure the amount of liquid water droplets in the
>> "steam" (ie. mass fraction of water vapor to to total water).  It measures
>> Relative Humidity (Relative Humidity measures how saturated the air is for a
>> given temperature).
>> What we want is a a device that measures "quality" of the steam.  For
>> reference, 100% quality = 100% vapor.
>> 
> 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.
>   

If it's pure steam (no entrained air) at 100 C, then the RH must be
100%, a priori, since the vapor pressure of water at 100 C is 1
atmosphere.  And at 101 C, pure steam will have a RH very close to 100%,
since it's only 1 degree above its dew point.  So it's not clear to me
what a RH meter is going to tell you that you don't already know,
particularly given that the meter is +/- 3.5 % at 99% RH.  (That assumes
they're in Bologna, which is only 54 meters above sea level, according
to some website or other.  If they were up in the mountains, the RH of
101 C steam would be lower, since the boiling point of water would be
lower, and we might expect 101 C steam to be drier, in general.)

Furthermore, I'm not sure it's correct to say <100% RH implies there
can't be entrained droplets.  The drops don't form in the steam, they're
blown/broken/pulverized off the surface of the water and carried off
with the steam.  They can be carried off with a stream of air at < 100%
RH just as easily as they can be carried off by a stream of pure steam. 
If it's <100% RH at the point where you measure it, then some way
downstream the steam may be expected to cool as the droplets evaporate,
which means the temperature reading your probe is reporting won't mean
what you think it does.



> Regards,
>
> Robin van Spaandonk
>
> http://rvanspaa.freehostia.com/Project.html
>
>
>   

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Harry Veeder]

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

Re: [Vo]:HP474AC probe measures Relative Humidity, not steam quality

[mixent]

In reply to  Jeff Driscoll's message of Sat, 22 Jan 2011 21:24:36 -0500:
Hi,
[snip]
>This probe does not measure the amount of liquid water droplets in the
>"steam" (ie. mass fraction of water vapor to to total water).  It measures
>Relative Humidity (Relative Humidity measures how saturated the air is for a
>given temperature).
>What we want is a a device that measures "quality" of the steam.  For
>reference, 100% quality = 100% vapor.

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.
Regards,

Robin van Spaandonk

http://rvanspaa.freehostia.com/Project.html

[Vo]:HP474AC probe measures Relative Humidity, not steam quality

[Jeff Driscoll]

Rossi used this electronic device for electronic measurement (as was
reported) - model  HD37AB1347.   Relative Humidity probe model HP474AC
was attached to it.
Page three of this link (thanks to Horace) shows details of that probe
connected to the electronic device.  HP474AC has the following
specifications:

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
This probe does not measure the amount of liquid water droplets in the
"steam" (ie. mass fraction of water vapor to to total water).  It measures
Relative Humidity (Relative Humidity measures how saturated the air is for a
given temperature).
What we want is a a device that measures "quality" of the steam.  For
reference, 100% quality = 100% vapor.
How did they confirm that the water vapor was truly vapor?  A visual
description would go a long way.
As was calculated in a previous email (and shown below), at a hose  diameter
of .44" (1 cm^2), the velocity of the water vapor should be 198 mph. At .63"
inner diameter (2 cm^2)  for the hose, the water vapor will be exiting at 94
mph.  Also the vapor should be transparent as it leaves the hose until it
starts to condense in the air.  I read that the steam was vented outside the
room.  What did it look like in terms of volume and transparentness?
I tend to believe that Rossi is legitimate (from what I hear on the
grapevine).  But we have to have our facts straight when it comes to listing
devices that measure relative humidity and saying they measure the quality
of the steam.  I'm open to the possibility that this probe can measure
quality of the steam in some undocumented manner, but let's hear how that is
done. The documentation does not say it.


from a previous email, below are the assumptions used to calculate the vapor
velocity:

Jeff D. wrote:
The calculations of the steam velocity below translates to a 188 mph jet of
steam coming out of a hose having an area of 1 cm^2  (equates to a 1.13 cm
inner diameter hose or .44" inner diameter)
Double the area of the hose and the velocity will drop by a factor of 2 to
94 mph.
Jones Beene wrote:
On Tue, Jan 18, 2011 at 3:35 PM, Jones Beene  wrote:
Here are some calculations that imply certain water/humidity effects which
should have been observed at the demo.
This is from an associate LENR researcher - Jeff Morriss, in response to the
other issues on steam/vapor raised by Jeff Driscoll and Peter van Noorden,
which so far do not have convincing answers.

Jeff M. wrote:
Nagel states that 150 grams of water are boiled every 30 sec, or 5 cc/sec.
Taking the density of steam at 100C as .590 Kg/m**3 and ratio-ing it against
the density of liquid water as 1000 kG/m**3 yields a volume increase of
1690. So each 5 cc of water is converted into 8450 cc of steam every second.
If we estimate the area of the vent hose at ~1 cm**2, then the steam
velocity must be 8450 cm/sec of 84.5 m/sec. This is about 1/4 the speed of
sound and should produce quite a jet of steam. Did anyone observe this?
Also, the steam would condense and quickly produce a saturated atmosphere
and condensation on metal surfaces. Again, did anyone observe this?