Originally Posted by fintstone (Post 7445325)

Read everything I could find from the EPA and never found a mention of a Porsche 911...perhaps you could quote them for us.

Originally Posted by fintstone (Post 7445325)

Read everything I could find from the EPA and never found a mention of a Porsche 911...perhaps you could quote them for us.

Originally Posted by SilberUrS6 (Post 7445344)

Actually, I was thinking about this the other day. Why in the hell did Porsche run all that soft line? Why not run hard line up and down the length of the car? Surely the tubing required would be lighter, the length of rubber hose much shorter - in fact it is conceivable to have less hose than in a front-engined car, due to the location of the components.

I've never seen an adequate answer, and have often wondered why hard line couldn't be used in place of hose. The difficulty I foresee is that you essentially double the the number of fittings and connections.

Originally Posted by wwest (Post 7445374)

Are saying that by default, since the 911 isn't mentioned, the statement doesn't apply to our factory installed "legacy" non-barrier hoses..?

Since Chrysler is the only marque mentioned by name then do they only apply to them..?

Originally Posted by fintstone (Post 7447813)

No, it just seemed that you were claiming that EPA made a claim regarding the 911 when you posted:

"Both the EPA and SAE are now on record stating that converting a Porsche 911 R-12 system to R-134a DOES NOT require switching to non-barrier A/C hoses."

Originally Posted by fintstone (Post 7447813)

No, it just seemed that you were claiming that EPA made a claim regarding the 911 when you posted:

"Both the EPA and SAE are now on record stating that converting a Porsche 911 R-12 system to R-134a DOES NOT require switching to non-barrier A/C hoses."

Originally Posted by kuehl (Post 7447688)

Wwest, why are you starting a thread based on 1 statement made by the EPA?

1 statement that seems to reverse their previous position which they have held securely for the past 20 years.
1 statement which they contradict their position on the same web page with the following:
" Cracked or damaged hoses should always be replaced with barrier hoses."
If the EPA feels or thinks non-barrier hoses are OK then why are they suggesting that if you need to replace them you need to use barrier hose? Does that make sense?
Can you explain that for the forum?
Why is the EPA flip flopping so much?

Here are just a few factual (published) studies on this 20 year old subject.
Let's start in the beginning, well before the consensus that refrigerants harm the environment:

SAE Technical Paper 710039, 1971
Permeation of Refrigerants Through Elastomeric and Plastic Hoses
“The effect of oil on refrigerant permeation was found to be relatively unimportant”.
Now here is a study not so much concerned on the environment but rather simply reducing R12 refrigerant leaks. And all published studies show that R134a leaks more than R12.

Clodic, D.,. Zero Leaks, 1996
“the estimated industry recharge prior to the conservationist activities was 1 every 3 years”, “In 1993, the replacement of refrigerant hose assemblies was reported on 21.1% of serviced vehicles. In 1997, the replacement of hose assemblies occurred on 11.1 of the service fleet”.
What this report says is that years ago, with non barrier hoses having oil in the hose and using a larger molecule refrigerant (R12), that vehicles needed to be recharged often. And, prior to fleet use of R134a (pre 1993), that non barrier hoses in vehicles were replaced 21% of the time during a service repair. And, after the introduction of R134a with barrier hoses (post 1992) that the need to replace a hose was cut in half (1/2). This report does not say non barrier hoses are better, rather it says barrier hoses need to be replaced less often if at all.

SAE Technical Paper 2005-01-2032, 2005
“the presence of oil had no effect on refrigerant emission with vapor in contact(***) with the hose (inner diameter), AND, to determine the contribution of hose permeation vs. coupling emission. it was determined that the overall contribution of coupling (i.e hose connections) emission to the overall refrigerant emission of the assemblies was very small.”.
So this report says having oil in non barrier hoses using R134a did not help to reduce leaks that much. And, hose connection points are not really the major source of leaks.

Mines ParisTech, by Yu Yingzhong, HFC-134a Emission Modes, 2008
“According to the results of several tests carried out during this research work, the presence of refrigerant oil has only a modest effect on permeation.” “Therefore it is important to choose low permeation hoses. , which appear suitable for MAC systems.”

So Wwest. Can you advise the forum of the factual scientific study the EPA is using to make their flip-flop-contradictory statement? What study(s), reports, papers, conclusive empirical data has the EPA provided to you directly, which is more conclusive of that presented by authoritative individuals, organizations, etc. ?

Originally Posted by kuehl (Post 7447688)

Wwest, why are you starting a thread based on 1 statement made by the EPA?

1 statement that seems to reverse their previous position which they have held securely for the past 20 years.
1 statement which they contradict their position on the same web page with the following:
" Cracked or damaged hoses should always be replaced with barrier hoses."
If the EPA feels or thinks non-barrier hoses are OK then why are they suggesting that if you need to replace them you need to use barrier hose?

Does that make sense?

Yes, perfectly. If I'm going to replace a factory idler arm using bushings then in most cases I'd choose the aftermarket one using ball bearings.

Can you explain that for the forum?

Why is the EPA flip flopping so much?

Because the early testing was done with new, off the shelf, non-barrier hoses. When testing was later done on USED non-barrier hoses the results differed significantly.

Thus the "FLIP/FLOP".

Here are just a few factual (published) studies on this 20 year old subject.
Let's start in the beginning, well before the consensus that refrigerants harm the environment:

SAE Technical Paper 710039, 1971
Permeation of Refrigerants Through Elastomeric and Plastic Hoses
“The effect of oil on refrigerant permeation was found to be relatively unimportant”.

Now here is a study not so much concerned on the environment but rather simply reducing R12 refrigerant leaks.

And all published studies show that R134a leaks more than R12.

Yes, but possibly because r-134a typically results in higher systems pressures if not controlled, limited somehow..?

Clodic, D.,. Zero Leaks, 1996
“the estimated industry recharge prior to the conservationist activities was 1 every 3 years”,

My own personal experience flies fully in the face of that "estimate".

“In 1993, the replacement of refrigerant hose assemblies was reported on 21.1% of serviced vehicles.

Wait,, WAIT..."21.1% of SERVICED VEHICLES. Of the total industry fleet of A/C equipped vehicles what % had to be serviced??? <1%...??? Is the above ESTIMATE based on RECORDS of SERVICED vehicles..?

In 1997, the replacement of hose assemblies occurred on 11.1 of the service fleet”.

"Service fleet,..or "serviced" fleet...?

"Serviced" fleet.. enuff said.

"Service" Fleet..?? USPS, government/corporate owned fleet...? What % is that of the overall..?

What this report says is that years ago, with non barrier hoses having oil in the hose and using a larger molecule refrigerant (R12), that vehicles needed to be recharged often.

No. It appears more likely to say that vehicles wherein the A/C had to be serviced for some reason, possibly reasons OTHER than non-barrier hose leakage, the hoses were replaced as a precaution.

And, prior to fleet use of R134a (pre 1993), that non barrier hoses in vehicles were replaced 21% of the time during a service repair.

Note that NO WHERE does the report state that wshen non-barrier hoses were replaced it was not done with NEW non-barrier hoses.

21% of the time during a service repair...

a.) with NEW non-barrier hoses..or...

b.) failed o-ring, connections..?

c.) College tuition?

And just what % of the FLEET required a service repair,....0.001%..?

And, after the introduction of R134a with barrier hoses (post 1992) that the need to replace a hose was cut in half (1/2).

Or was it also due to the EPA's required use of a pressure switch..and thereby lower system operating pressures even with R-134a..?

This report does not say non barrier hoses are better, rather it says barrier hoses need to be replaced less often if at all.

No, it simply says that in that timeframe the EPA was forcing the industry to be a lot more conscious of the problem.

SAE Technical Paper 2005-01-2032, 2005
“the presence of oil had no effect on refrigerant emission with vapor (= low side) in contact with the hose (inner diameter), AND, to determine the contribution of hose permeation vs. coupling emission. it was determined that the overall contribution of coupling (i.e hose connections) emission to the overall refrigerant emission of the assemblies was very small.”.

So this report says having oil in non barrier hoses using R134a did not help to reduce leaks that much. And, hose connection points are not really the major source of leaks.

No, it says ONLY that oil permeation had no effect on the low pressure side. Which is why Chrysler continued to use non-barrier hoses on the low pressure side.

Mines ParisTech, by Yu Yingzhong, HFC-134a Emission Modes, 2008
“According to the results of several tests carried out during this research work, the presence of refrigerant oil has only a modest effect on permeation.”

Statement context, non-barrier or the new barrier hoses...? 2008...why would anyone be testing the permeation rate of old, OBSOLETE, non-barrier hose at this late date..? More likely addressing one type/brand of barrier hose vs another.

“Therefore it is important to choose low permeation hoses. , which appear suitable for MAC systems.”

So Wwest. Can you advise the forum of the factual scientific study the EPA is using to make their flip-flop-contradictory statement?

YES.

What study(s), reports, papers, conclusive empirical data has the EPA provided to you directly, which is more conclusive of that presented by authoritative individuals, organizations, etc. ?

Originally Posted by kuehl (Post 7448867)

So, Wwest. Question for you.

Assume its 90F outside. You have in your possession a Porsche 911 (78-89; SC or Car.) with a stock AC system (stock non barrier hoses, 2 condensers, etc) running either R12 or R134a. An AC technician has just confirmed for you that refrigerant level is to factory spec., the ac controls are working (thermostat turns off system when it should), vents blowing colder air than outside naturally. The AC technician also injected dye tracer, found no leaks, and then he inspected every AC component connection, and component, with an electronic refrigerant detector (heated-diode type) and has announced there are no apparent leaks. The system pressures are running 240 psi on the high and 30 psi on the low; we will just accept these numbers for the moment.

You take the car out for a 1 hour drive, driving the vehicle as hard as you can handle with the AC running all the time (compressor is cycling on and off as the thermostat says it needs to).

After the hour drive you immediately stop back to see the AC Technician. He quickly attaches a service gauge set and notes the readings with the engine running and compressor engaged, 260 high and 35 low. You turn off the engine and compressor.
The deck lid is put down as far as it will go, you don't want to crush the hoses to the service set, you place thick moving blankets around the gaps between the deck lid and the body.

1) What happens to the high side and low side pressures during the 15 minutes or so that you and the AC tech are observing the gauges?

Assuming the TXV is mostly closed because the evaporator outlet line is near freezing (that's how you get 34F vent temperatures), the compressor was about to cycle off, and since you just terminated both condensor cooling airflow sources the high side pressure would rise within minutes.

2) After the 15 minutes the AC tech takes out his black light and inspects every hose and component connection, and components as well. What does he see?

My vote would be...NOTHING..

3) A moment after that the AC tech takes out his electronic refrigerant sniffer and checks the same joints and components. What does he observe?

Nothing, unless the sniffer is really sensitive.

PS, if you decide to respond you don't have to quote this entire post (let's save on hosts memory and the annoyance of reposts), just answer the 3 questions.
Thankyou.

Originally Posted by kuehl (Post 7449177)

I see.

And you say the high side pressure would rise.. hmmm. How high?

I think you already verified pressures beyond 450 PSI...

And, what about the low side pressure, what would happen to it?

Sorry, overlooked that, it would rise, slowly, rate dependent on the TXV apperature.

Let's assume the electronic detector is accurate for leaks
as small as .1 (one tenth) ounces per year.