The Myth, Fable and Hoax of "R410A must be charged LIQUID (you need a cat license)

[daveca]

... else the universe will be destroyed. Youlll suffer a fate worse that falling in the Thames.

The Blancmange will get you!

It is fun to make up Tall Tales. Spin stories, Tell Whoppers.

Many Myths are based on a small kernel of fact, widely known, then the Myth Weavers embellish to make themselves stand out and appear wise and important.

This is oft-attended by using Logical Fallacies such as:

White Knight
False Equivalence
Wild Overgeneralisation
Appeal to Authority
Wisdom of the Ages

and outright Lying...

all of which and more attend the MYTH that 410 MUST be charged liquid.


Being an HVAC RESEARCH ENGINEER, and having been a HVAC mechanic and technician, I thus point out WHY thats false from AUTHORITATIVE sources, none of which is the opinion of a refrigeration MECHANIC.

The Myth is that R410A Must Be Charged Liquid else the universe will implode, is based on the kernel of truth that 410 is a two component mixture where the components have different vapour properties and separate, so it MUST be charged liquid-phase else....

.. else they have no idea WHAT happens, but you dare not do so because they are the authority and they have a REfrigeration License and you dare not challenge them a-riding in on their White Steed to save you from eternal destruction else they will call the Refrigeration Police on you.

Or worse, the Church Police.

Neither can they explain the refrigerant properties which cause that claimed phenomenon, nor can they explain how MUCH of a difference will be made.

In other words, this is an OPINION without basis which the Opinioner cannot defend.

"...thoughts they cannot defend" to quote Moody Blues.

Reasons why CAN 410 be charged vapour:

1. There is no such thing as "charging liquid" according to common HVAC thinking.

The Golden Rule is "NEVER charge liquid into a compressor inlet else the compressor will be "slugged" and may be damaged.

My mechanical engineering background says "possibly, depending on the system and compressor design, but again, those claiming that never explain it or show proof.

There is, fundamentally no such thing as charging vapour-phase. Charging into an evacuated system is a guarantee that even if the refrigerant cylinder dispenses liquid, that at the first restriction (manifold, hose, charging valve) the liquid WILL conver to vapour and enter the system as vapour.

Where is that? Wherever the system turns cold.

If the system is empty, it is guaranteed to vaporise upon entering.

P & T and phase data indicate that refrigerants thru a restriction expand from liquid to vapour, or less dense vapour, thats what cooling is all about!

The White Knights scream and threaten "you cant charge liquid" then turn right round and lecture "get one of those charging adapters to prevent slugging the compressor, those ones that VAPORIZE THE REFRIGERANT."

It must be a Magic Charging Hose that somehow, mysteriously, then takes that vapour and reverts it to liquid to then dump it into the sealed system to then likey become vapour again to the end of Universal Destruction.

(Magic Hose, Patents pending)

2. The myth is based on a Wild Overgeneralization and False Equivalence of "R410 is two components with a temperature glide so it cannot be charged vapour because unequal amounts will be dispensed into the sealed system and that MIGHT compromise performance."

This is the Religious Dogma chanted by the Gnostic Adherents.

All false or conditionally (un)true.

"Glide" denotes the temperature difference of the two components on a phase graph. Going up and down the graph, the two components are separated.

By a gnats eyebrow. Irrelevant. See R410A Manufacturers physical properties data. Not a trade mechanics opinion.

IF there is a separation, it only exists in vapour -phase. God(s) help us if it's also separated in liquid phase!

The problem with pretending that is relevant in CHARGING a sealed system from a cylinder over relatively short hoses is that the hose etc. VOLUME between the cylinder and sealed system inlet is extremely small and the velocity at which the refrigerant escapes the cylinder and goes into the system is rapid. So there may be a separation into two vapour components, but ALL OF THAT MIXTURE GOES INTO THE SEALED SYSTEM.

Therefore, it is irrelevant if it separates, it WILL SEPARATE IN THE SEALED SYSTEM!

The system under normal operation contains vapour-phase refrigerant, it cant be all that dangerous!

Were the liquid to be dispensed into a large VOLUME, then one or the other component MIGHT be transferred preferrably, but that will not happen in any significant degree in a VERY small volume of a charging hose.

AS to the term "Glide", Du Pont says THERE ISN'T ANY.

Source- Du Pont Suava Technical Information document, "P407C/410A, (6/03) 247249C"
DuPont 410 UNI-99862_Broc.pdf
page 2:

Temperature Glide, °C (°F) 0 (0) 4.9 (8.9) 0 (0) (R410)

No Glide, no separation, no difference.

There are sources I have read, from refrigerant MANUFACTURERS that claim a Glide of 0.1K.

that figures to 0.2 F at 70F. IRRELEVANT.

This is a Fallacy of "All or none". Wisdom of the Ages.

3. Being a Research Engineer, I specialise in challenging Laws of Physics (I always lose) and Myths and Urban Legends (usually win).

So, a test.

I charged a R410A heat pump (Trane XL14C- good engineering, miserable construction)
with 7.5 lbs of 410A AND CHARGED IT NOT ONLY VAPOUR, BUT WITH THE COMPRESSOR NOT RUNNING, to challenge another myth.

The compressor cant run, it hasnt got any legs, Mater!

I also (gasp) used HOT WATER to do the charging. No fancy charging pumps.

The system charged to full amount, it started and ran perfectly.

The root of this myth is shown in another Du Pont paper:

R-410A – Application Experience, D. B. Bivens, J. R. Morley, W.Wells, DuPont Fluoroproducts
found on http://www.eurocooling.com/public_html/articler410a.htm

(Likely research chemists whose boots I am not worthy to lick...(another Monty Python reference)


Quote:

"The industry (refrigerant manufacturers and air conditioning system OEMs) initially settled on R-407C as being the preferred replacement for R-22 for air conditioning. However R-407C, being a zeotropic mixture with a significant temperature glide, is not suitable for all (specifically certain chiller) air conditioning applications. "

Only SOME limitations. Not "all or none"

Further:

"R-410A: R-410A is a near-azeotropic mixture of HFC-32 and HFC-125. It has a very low temperature glide (around 0.1K), however it is truly zeotropic over its useable temperature range – the composition of its vapour in equilibrium with the liquid at any temperature (below the Critical Point) is different from the composition of the liquid phase. This means that, although R-410A has a very low temperature glide it should not be handled as an azeotropic fluid: transfers should always be made from the liquid phase."

AHA, exclains the Refrigeration Mechanic- "See I told you so, you cannot charge R410A vapour."

CRITICAL STOP.

NEAR AZETROPIC, NOT ZEOTROPIC.

The EXPERTS did not say "charge" they said "TRANSFER." BIG DIFFERENCE.

This is where the Kernel of Truth is picked up by uneducated lot and blown into a world-ending crisis, Overgeneralsation, False Equivalence etc.

The term TRANSFER is said in context of a refrigerant MANUFACTURER who likely made 10 zillion litres of the stuff, TRANSFERRING IT FROM ONE LARGE VESSEL TO ANOTHER.

Well of COURSE they wont transfer it vapour, thats too slow.

They, a Manufacturer, are held to extremely strict MANUFACTURING PROCESS AND QUALITY STANDARDS.

They must take that zillion litres and ship it to Distributors who knock it down into little bits for we lot to charge our AC with.

That is a MUCH different matter than then taking that microscopically small cylinder and CHARGING INTO AN EQUALLY MICROSCOPIC SEALED SYSTEM!

This is where the uneducated Mechanic picks up a tiny shred of information and spins it into a Giant Web.

I read the scientific documents, phase data, properties data, and CALCULATED that even if there is a glide (Du Pont says there ISNT) then it is so extremely small that I would never notice it.

And that is exactly how my experiment-proof turned out.

Not a shred of difference.

[daveca]

Correction:

"There is, fundamentally no such thing as charging vapour-phase."

should read:

"There is, fundamentally no such thing as charging liquid-phase."

Larger point is, its irrelevant the mixture. Its the SAME quantities of both in either liquid or vapour conditions.

The glide is NOT about charging, it is about the P-T performance in the operating system. The two components may have a small difference in P-T performance in operation.

[seanf]

I'm not sure anyone in your other thread mentioned charging the system.

Again I'm just a daft parts fitter. So I tend to take into consideration what the more educated and experienced have to say.

I'd be interested to know if you've found from your own practical experience or from your reading of papers/manufacturer info, if loosing vapour from a R4... system gave any noticable change?