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  1. #1
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    Carters Widget Revealed!



    I have been teasing you guys with what maybe?? a potential way of increasing the net refrigeration effect of a refrigeration system. i would like to thank DesA and Chef for their input to date.
    Basically, i have built a number of test riggs, with limited resources and knowledge. i have had a wide range of results from very good to the exact opposite. And very little or no repeatability.
    before we get to technical in my mind the widget, is simple to make (low cost) for those who have the right machines (lathes ect), simple to install and commission. (But I could be wrong)
    We do have to make a start and the best way is to ensure that we understand how the very basic system works.
    I am looking for alternative opinions, so i will be asking the questions, in a method to build up how the widget works. (it is best not to guess what is coming next, but just to focus on the question being asked)
    i would suggest that this will be a good method for those who are early in the trade to grasp the very fundementals of the refrigeration cycle (which in my opinion is now grossly overlooked in modern training)



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    Re: Carters Widget Revealed!

    Great thread. Promises to be a very interesting one. Keep it coming.
    Engineering Specialist - Cuprobraze, Nocolok, CD Technology
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    Re: Carters Widget Revealed!

    Starting with a blank page (do not think about previous threads, this will only mislead this part)

    We have a normal simple refrigeration system (LT coldroom for example)

    We are going to presume to keep it simple that there is no pressure drops, glide, heat gains or losses .

    So we have high pressure liquid (from reciever) for ease at saturation but 100% liquid. It passes through the expansion valve into the evaporator. (no evap pressure drops)

    So how do we determine the net refrigeration effect (how much cooling is taken from the coldroom)?

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    Re: Carters Widget Revealed!

    Net refrigeration effect:

    Q'evap = m'r*(hout-hin) = m'r*(1-x)*hfg@Te,sat
    Engineering Specialist - Cuprobraze, Nocolok, CD Technology
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    Re: Carters Widget Revealed!

    Quote Originally Posted by desA View Post
    Net refrigeration effect:

    Q'evap = m'r*(hout-hin) = m'r*(1-x)*hfg@Te,sat
    So for those who may not be use to scientific or maths terms what does this mean! keeping it simple!

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    Re: Carters Widget Revealed!

    Net refrigeration effect:

    Q'evap = m'r*(hout-hin) = m'r*(1-x)*hfg@Te,sat
    Key :
    m'r = refrigerant mass flowrate [kg/s]
    hout = enthalpy of refrigerant leaving evaporator [J/kg]
    hin = enthalpy of refrigerant entering evaporator [J/kg]
    x = vapour fraction of 2-phase fluid [kg/kg]
    hfg = latent heat of vapourisation at evaporator saturation pressure [J/kg]

    Strictly, to manage the exit superheat in the evaporator:

    Q'evap = m'r*(h'out-hin) = m'r*(1-x)*hfg@Te,sat + m'r*Cpv*SH

    where:
    h'out = enthalpy of refrigerant leaving evaporator - superheated vapour state [J/kg]
    CPv = exit vapour specific heat [J/kg.K]
    SH = superheat [K]
    Last edited by desA; 21-08-2011 at 12:08 PM.
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    Re: Carters Widget Revealed!

    OK, keeping it simple, if we had NO superheat at the exit of the evap, would the flash gas in the evap have any effect on the net cooling of the room. (energy only)

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    Re: Carters Widget Revealed!

    Quote Originally Posted by mad fridgie View Post
    OK, keeping it simple, if we had NO superheat at the exit of the evap, would the flash gas in the evap have any effect on the net cooling of the room. (energy only)
    Yes.

    Simply put, as flash gas is reduced, 'x' will reduce (ie. less vapour in incoming 2-phase fluid) - this will increase Q'evap (refrigeration effect). (A few simplifying assumptions in this, so far)
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    Re: Carters Widget Revealed!

    Quote Originally Posted by desA View Post
    Yes.

    Simply put, as flash gas is reduced, 'x' will reduce (ie. less vapour in incoming 2-phase fluid) - this will increase Q'evap (refrigeration effect). (A few simplifying assumptions in this, so far)
    Are you sure?

    I will re word. Liquid is at fixed pressure and temp (saturated). It enters the expansion valve, expands (reduction in pressure) So just before it enters the evaporator we a % of vapour by mass (weight) and a % of liquid by mass.
    If there in no pressure drop in the evap and no superheat at the exit of the evap, 100% by mass is all vapour at saturation leaving the evap.
    Does the original flash gas (that entering the evap) have any benefit to the net cooling.?

    We are looking at energy only, not effect on heat transfer co-efficients

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    Re: Carters Widget Revealed!

    Just noticed this one again... Interesting.

    The flashgas is taken into account for calculation of the net refrigeration effect.
    Will try to explain my vision: all the bubbles together present at the exit of the TXV have a certain mass at a certain enthalpy. During the pass through the evaporator, they will absorb heat, so the enthalpy will change and....

    No, wrong Peter, twisting my brain again,..If it's already 100% gas and we add heat, then it becomes superheated. The bubbles are already at a complete gaseous phase, surrounded by liquid which still can absorb heat, So, the flashgas is already at the condition like we will find finally all the liquid on the right side of the saturated curve. Due to the fact that the flashgas is already 100% gas, it must be positioned on the right side of the curve.

    What's Carters Widget, a little bit difficult for me to translate..what's widget anyway?
    Last edited by Peter_1; 21-08-2011 at 05:35 PM.
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    Re: Carters Widget Revealed!

    A widget is an undefined/unnamed mechanical device; a gadget; a thingamajig; a whatchamacallit. If you see something and you don't know what it's name is, you might call it a widgit.
    Last edited by Gary; 21-08-2011 at 06:25 PM.

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    Re: Carters Widget Revealed!

    Quote Originally Posted by Peter_1 View Post
    If it's already 100% gas and we add heat, then it becomes superheated.

    The bubbles are already at a complete gaseous phase, surrounded by liquid which still can absorb heat,

    So, the flashgas is already at the condition like we will find finally all the liquid on the right side of the saturated curve.

    Due to the fact that the flashgas is already 100% gas, it must be positioned on the right side of the curve.
    Question Gents, Please correct me,

    What your saying Peter is, that the 2phases, will not follow their respective curves of the bell &

    1. the liquid = saturated liquid
    2' the vapour = superheated vapour
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    Re: Carters Widget Revealed!

    Quote Originally Posted by Gary View Post
    A widget is an undefined/unnamed mechanical device; a gadget; a thingamajig; a whatchamacallit. If you see something and you don't know what it's name is, you might call it a widgit.
    And where's Carter coming from?
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

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    Re: Carters Widget Revealed!

    Quote Originally Posted by chillerman2006 View Post
    Question Gents, Please correct me,

    What your saying Peter is, that the 2phases, will not follow their respective curves of the bell &

    1. the liquid = saturated liquid
    2' the vapour = superheated vapour
    Once in the bell, both gas and liquid is saturated.
    Now I will make a perhaps strange jump: isn't is possible that the gas in the mixture is movings straight to the right too its saturated point and not going vertical, starting from the throttling device?
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

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    Re: Carters Widget Revealed!

    Quote Originally Posted by Peter_1 View Post
    And where's Carter coming from?
    I'm guessing Carter = mad fridgie

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    Re: Carters Widget Revealed!

    Quote Originally Posted by mad fridgie View Post
    OK, keeping it simple, if we had NO superheat at the exit of the evap, would the flash gas in the evap have any effect on the net cooling of the room. (energy only)
    Right time to jump in with both feet.

    The flash gas is caused where the energy contained in the liquid refrigerant entering the TEV is used to lower the temperature of itself to get to the boiling point in the evaporator.

    i.e. Te is -30*C, Tc 35*C subcooling 5K means as ref. enters the TEV at 30*C it has to drop temperature by 60K to boil. Ideally the temperature of liquid feed to the TEV would be as low as possible as this shifts the expansion line on a PE chart over to the left into the higher % region of liquid/vapor mix. If it was 100% that means the liquid at the TEV was already at -30*C. If it was you wouldn't really need a refrigerant circuit as you somehow had the means to get refrigerant at the same temperature as Te so you'd use that means instead.

    So in answer the flash gas has no net effect in cooling the room. It only cools the refrigerant to the evaporators boiling point.

    How does that sound?

    Cheers,
    Andy.
    Health and safety first..........unless I'm in a hurry.

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    Re: Carters Widget Revealed!

    Quote Originally Posted by Gary View Post
    A widget is an undefined/unnamed mechanical device; a gadget; a thingamajig; a whatchamacallit. If you see something and you don't know what it's name is, you might call it a widgit.
    Quote Originally Posted by Peter_1 View Post
    And where's Carter coming from?
    The widget is the name often referred to as the little plastic ball in a can of draught, bitter, guiness etc,

    Carter are a brand that uses the widget

    R's chillerman
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    Re: Carters Widget Revealed!

    Removed as so - not to confuse the thread - with another
    Last edited by chillerman2006; 21-08-2011 at 10:33 PM. Reason: Removed as so not to confuse the thread
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    Re: Carters Widget Revealed!

    mad fridgie = carter.
    I have to agree with Tayters (well written)
    Only when we introduce superheat in the evap does the flash gas have any effect on the net cooling (energy only)
    A very simple statement " the amount of liquid which is boiled in the evaporator determines the net cooling effect"
    More liquid boiled more refrigeration, less refrigerant boiled less refrigeration.
    Can we are agree on this very basic statement.

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    Re: Carters Widget Revealed!

    The first few questions are not directly related to widget, just simple understand of how a refrigeration system works. We all need to agree on certain effects. They are not trick questions, just something we all always take for granted.
    if I just stick the design out then we will get confused. It is coming!

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    Re: Carters Widget Revealed!

    Quote Originally Posted by mad fridgie View Post
    I have to agree with Tayters (well written)
    Only when we introduce superheat in the evap does the flash gas have any effect on the net cooling (energy only)
    A very simple statement " the amount of liquid which is boiled in the evaporator determines the net cooling effect"
    More liquid boiled more refrigeration, less refrigerant boiled less refrigeration.
    Can we are agree on this very basic statement.
    Spank yer hairy crutch!

    The bit in red, now I'm a bit lost.
    Flash gas = expanding liquid in TEV lowering temp of refrigerant to Te
    Superheat = heat energy absorbed when all liquid boiled off. Not as good at absorbing heat as it's sensible as opposed to latent.

    How can superheat affect flash gas?
    Surely flash gas should be kept to a minimum which is down to subcooling, superheat is due to how much boiling refrigerant is in the evaporator in the first place and becauseit comes after the flash gas part I can't see why it would affect it?

    Andy.
    Health and safety first..........unless I'm in a hurry.

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    Re: Carters Widget Revealed!

    At the end of a normal evap, we now have the combination of the original flash gas produced and the vapour produced during boiling (load) If this combination is superheated in the evap (what is used to control the TEV) then the total mass must absorb energy from the room, so extra net cooling is created by the flash gas proportion and vapourised proportion "superheat" (words are not my fortie)

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    Re: Carters Widget Revealed!

    Next question,
    again keeping it simple.
    We have the simplest of compressors suction and discharge. (fixed speed, fixed displacment)
    We can maintain a constant outlet pressure
    we have a suction pressure, and for ease at saturation ("O no that will f*** the comp)
    This will give us a certain mass flow.
    Again only looking at the compressor (not the system) How do we increase the mass flow through this compressor?
    Not a trick question

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    Re: Carters Widget Revealed!

    increased suction pressure?

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    Re: Carters Widget Revealed!

    increase the frequency on the power input

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    Re: Carters Widget Revealed!

    Quote Originally Posted by install monkey View Post
    increased suction pressure?
    Yes! Simple but important later

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    Re: Carters Widget Revealed!

    So to clarify the above 2 questions 100% mass enters the compressor, 100% leaves the comp, 100% passes through the cond, 100% pass through the expansion device, 100% pass through the evap then back to the comp.

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    Re: Carters Widget Revealed!

    Quote Originally Posted by mad fridgie View Post
    Yes! Simple but important later
    do i get a bonus point for a quick answer?? the suspense is killing me,can i buy 1 to tinker with??

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    Re: Carters Widget Revealed!

    We are getting close.
    Imagine if you can we have an intermediate pressure vessel (very much like an open flash economiser on a screw set)
    High pressure liquid in, pressure drops, liquid at the bottom, vapour at the top.
    For ease we will say that the pressure in mid way between the Saturated cond pressure and the Saturated Suction pressure.
    Now Focusing on the liquid proportion "only" (the liquid which is leaveing the vessel) and we are talking about energy only, would the new liquid mass flow change the net refrigeration cooling

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    Re: Carters Widget Revealed!

    Quote Originally Posted by install monkey View Post
    do i get a bonus point for a quick answer?? the suspense is killing me,can i buy 1 to tinker with??
    Very close to being revealed.

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    Re: Carters Widget Revealed!

    .

    Make the vapour Denser.



    Oh and I agree with Tayters description of of liquid flashing off through the
    expansion valve only to drop the temp of the refrigerant.

    If the refrigerant is at a saturated state entering the valve and there is say
    30 or 40 degs of temp drop in the refrigerant then you may loose as much as
    40 to 50% of the quality of the refrigerant.

    coolrunnings

    .

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    Re: Carters Widget Revealed!

    The vessel is part of Carters Widget

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    Re: Carters Widget Revealed!

    Quote Originally Posted by mad fridgie View Post
    We are getting close.
    Imagine if you can we have an intermediate pressure vessel (very much like an open flash economiser on a screw set)
    High pressure liquid in, pressure drops, liquid at the bottom, vapour at the top.
    For ease we will say that the pressure in mid way between the Saturated cond pressure and the Saturated Suction pressure.
    Now Focusing on the liquid proportion "only" (the liquid which is leaveing the vessel) and we are talking about energy only, would the new liquid mass flow change the net refrigeration cooling
    If we have pure liquid, mass flow will increase

    Mass has increased with the removal of vapour ???

    Increaseing net refrigeration efficiency (cooling)
    Last edited by chillerman2006; 22-08-2011 at 12:30 AM. Reason: missed a bit
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    Re: Carters Widget Revealed!

    Drop the liquid pressure and temperature, syphon off the vapour to suction line to maintain low superheated or near nil superheated vapour to compressor for maximum volumetric efficiency and less overall energy wasted in compressing to higher discharge pressure. In return, the lowered liquid pressure, but more important, the lower liquid temperature, without any vapour, and maintaining constant pressure entering evaporator, uses the least amount of energy of itself and allows increased performance through evap coil, so long as rifled tubing is employed.. Now correct me as my neck is firmly wedged on the chopping block and some masked man with a large axe is standing over me.
    To the optimist, the glass is half full. To the pessimist, the glass is half empty.

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    Re: Carters Widget Revealed!

    Well good input from both,
    Infact if we just look at the "liquid part only", as determined in the first question, the net refrigeration remains the same, as the flash gas has no effect on the net cooling ( to keep it simple we are basing all observations when the refrigeratant is at saturation)

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    Re: Carters Widget Revealed!

    Quote Originally Posted by mikeref View Post
    Drop the liquid pressure and temperature, syphon off the vapour to suction line to maintain low superheated or near nil superheated vapour to compressor for maximum volumetric efficiency and less overall energy wasted in compressing to higher discharge pressure. In return, the lowered liquid pressure, but more important, the lower liquid temperature, without any vapour, and maintaining constant pressure entering evaporator, uses the least amount of energy of itself and allows increased performance through evap coil, so long as rifled tubing is employed.. Now correct me as my neck is firmly wedged on the chopping block and some masked man with a large axe is standing over me.
    You've not just answered this question you have answered the next few coming up
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    Re: Carters Widget Revealed!

    Now The vapour side of the vessel?
    Is this vapour at a higher or lower pressure than that at the evap outlet. (and what would its properties be chef's question)

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    Re: Carters Widget Revealed!

    Quote Originally Posted by chillerman2006 View Post
    You've not just answered this question you have answered the next few coming up
    Even though his asumbtions maybe correct, not the widget method. This net refrigeration capacity could increase a little but not a lot

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    Re: Carters Widget Revealed!

    Quote Originally Posted by mad fridgie View Post
    Now The vapour side of the vessel?
    Is this vapour at a higher or lower pressure than that at the evap outlet. (and what would its properties be chef's question)
    Higher pressure

    Pure Vapour
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    Re: Carters Widget Revealed!

    We are just about here.

    Do you know what, a venturi, jet compressor, ejector or condell mover is?

    basically a device that has a motive force (a high(er) pressure feed), a suction port (lowest pressure) and an outlet pressure (which is the sum of the motive and suction mass streams) medium pressure

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    Re: Carters Widget Revealed!

    Quote Originally Posted by mad fridgie View Post
    We are just about here.

    Do you know what, a venturi, jet compressor, ejector or condell mover is?

    basically a device that has a motive force (a high(er) pressure feed), a suction port (lowest pressure) and an outlet pressure (which is the sum of the motive and suction mass streams) medium pressure
    I know how a ram air jet compressor works,
    Last edited by chillerman2006; 24-08-2011 at 04:36 AM.
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    Re: Carters Widget Revealed!

    The vapour from the vessel becomes the motive force (highest pressure)
    The vapour exiting the evaporator enters the suction port (lowest pressure)
    The combined flow leave the devices and enters the compressor.(medium pressure)

    effectivly we have a 2 stage compression system.

    The suction of the compressor would be higher than if it came just from the suction.

    The compressor mass flow would increase (higher inlet pressure)

    So the total system mass flow would increase, including increased liquid mass flow through the evaporator.

    Carter Widget (simplified)

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    Re: Carters Widget Revealed!

    O.k. Stay of execution for now. Saturated vapour but not to the point of liquid to compressor. Has to be higher pressure than evap. outlet so it can be throttled down. Seperate line supplied to compressor?
    To the optimist, the glass is half full. To the pessimist, the glass is half empty.

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    Re: Carters Widget Revealed!

    Quote Originally Posted by mikeref View Post
    O.k. Stay of execution for now. Saturated vapour but not to the point of liquid to compressor. Has to be higher pressure than evap. outlet so it can be throttled down. Seperate line supplied to compressor?
    No it goes through a device like a "venturi" for ease of desription and mixes together.

    Ok another way of looking at.

    You have 2 closed buckets, each has the same refrigerant in it, but at 2 completly different pressures/temperatures (saturation) High and Low. If there was a pipe between the 2 buckets and valve. If we opened the valve what would happen to the pressures inside the 2 buckets?

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    Re: Carters Widget Revealed!

    So (if I am understanding this correctl) the mass flow is increased to the widget by removing the vapour (same as push/pull recovery of a system)

    The increase in mass increases the compressors mass flow rate

    Which in turn increases system mass flow rate

    ????????
    If the World did not Suck, We would all fall off !

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    Re: Carters Widget Revealed!

    Have to equalise, high to low and initially the higher pressure bucket would turn cooler till equalisation established.
    To the optimist, the glass is half full. To the pessimist, the glass is half empty.

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    Re: Carters Widget Revealed!

    Damn, C.m. are you connected to IBM, or on speed?
    To the optimist, the glass is half full. To the pessimist, the glass is half empty.

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    Re: Carters Widget Revealed!

    Quote Originally Posted by chillerman2006 View Post
    So (if I am understanding this correctl) the mass flow is increased to the widget by removing the vapour (same as push/pull recovery of a system)

    The increase in mass increases the compressors mass flow rate

    Which in turn increases system mass flow rate

    ????????
    Yes basically, but it is a "non steady state" system to start (it does not happen instantly) until it reaches equalibrium, and is a circular calculation (no start or end), which does make hard to understand.

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    Re: Carters Widget Revealed!

    Try this very basic device.

    A piece of 7/8 pipe 6' long, stick your oxy/act tip in on end (middlish if possible) leave this end still open to the air, turn on oxygen (really you should use nitrogen to be safe) but it is the tip that is important. (motive force)
    What you should see is that air is pulled into the pipe at one end (suction) and quite alot flow coming out of the other end. ( alot more flow that just the oxygen flowing from the tip)

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    Re: Carters Widget Revealed!

    Quote Originally Posted by mikeref View Post
    Damn, C.m. are you connected to IBM, or on speed?
    Mozilla 6, sssssshhhhhh, im trying to learn

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