John, thanks for the input. Can you talk more about the efficiency improvements with hydrocarbon refrigerants? I've heard 10% but I'm sure it is more complex than that.

Germany had problems with entrenched refrigerant manufactures and exaggerated danger claims, but Greenfreeze eventually prevailed.

Posted By engineer on 08 Apr 2010 07:57 PM
I'm enjoying the robust discussion as well.

In some ways vehicle use concerns me less since most of the system, and all its high pressure components are located outside the firewall. We do accept the explosive risks associated with gasoline every time we drive. (Although 2 out of 3 of my vehicles are Diesel, and I feel quite a bit safer with Diesel fuel's lower volatility.)

Yet another hat I wear is that of part time watercop, and I've worked a few boat fires, never a pretty sight. Most involve gasoline and an accumulation of vapors in low lying compartments aboard, combined with an electrical fault. I occasionally teach a vessel systems module to marine law enforcement officers who may be first responders to vessel accidents. I don't pretend to be an expert in the field, but I go over some basics and set a few things on fire, a nice break from the slow death by powerpoint that characterizes most cop training.

This being a geo site, let me steer back to course. One of the advantage of geo systems is being able to locate all of a system's components inside, out of the weather. Unfortunately for a system using hydrocarbons, that gives rise to the possibility of an explosive cloud forming quite quickly in a basement if a high side component lets go.

I agree that Mercaptan would annunciate that situation, and I don't ignore the risk of NG in the home. However home gas piping is limited to vapor only under very low pressure. NG does still blow up the odd house every now and then.

The father of a childhood friend of mine, a renowned plastic surgeon, blew up his own house 10 years ago after dislodging a gas line with a rented earthmover. No one was hurt but the house was reduced to kindling. I spent many nights there in the late 70s, so the incident sticks in my mind.

I'm always open to new ideas supported by data, but I remain guided by concerns of a basement bomb I described above.

Curt,

I agree with everything you said in that post.

Regarding risks, I would very briefly summarise it as this: assess the proposed installation. If the potential leak points, failure points etc are easy to assess on the back of an envelope then do that, determine if there is going to be any significant risk and if so, mitigate it or drop the idea altogether. If the potential hazards are more complex, do a fault tree diagnosis (on the general design and installed surroundings or, as the case may be, on a site-by-site basis) and if the analysis comes up OK, then proceed otherwise drop it.

However, I think that is the essential process for ALL refrigerant plants, no matter what refrigerant they use.

Unfortunately in future it may not be as easy as simply walking through the application of a national or international standard either, because the monopolists have voting block control over much of the standards committees (which is concentrated even further at the ISO level, due to the way the voting system works). These pr*cks are using these technical committees as a tool for keeping naturals out of their markets.

Cheers

John W Clark
HyChill Australia

Posted By jonr on 08 Apr 2010 08:22 PM
John, thanks for the input. Can you talk more about the efficiency improvements with hydrocarbon refrigerants? I've heard 10% but I'm sure it is more complex than that.

Germany had problems with entrenched refrigerant manufactures and exaggerated danger claims, but Greenfreeze eventually prevailed.

Dear jonr,

Yes, a properly selected hydrocarbon will outperform any of the major fluorocarbons when compared apples-to-apples.

Unfortunately there is unnecessary confusion in the literature (not often in the peer-reviewed stuff, but more in the general reports flying around industry) due to what is quite plain attempts to select an inappropriate hydrocarbon to compare against a fluorocarbon (e.g. comparing R134a against propane - totally inappropriate).

Performance gains are hard to measure outside a careful laboratory environment, but the data indicates around the 10% improvement mark. That is, 10% reduction in energy consumption per unit cooling capacity. But it's usually better than 5% and can sometimes approach 20%, depending on various factors.

Performance gains increase as environmental conditions get harsher (hotter).

There's also an important issue of system longevity. Hydrocarbons are chemically much more stable than halocarbons. Specifically, hydrocarbons won't form acids in the presence of moisture. If you use a hydrocarbon refrigerant in combination with a hydrocarbon lubricant, you end up with a system that is completely non-corrosive internally. That can have considerable impact on system longevity, which is also a kind of energy/cost efficiency gain.

There's much literature about these issues. Here's one: Why Hydrocarbons Save Energy (AIRAH Journal).

Kind regards,

John W Clark
Technical Advisor
HyChill Australia Pty. Ltd.
85a Canterbury Rd, Kilsyth, Victoria, Australia
Freecall (aus): 1300 492 445  Ph: +61 3 97285055  Fax: +61 3 97618799
http://www.hychill.com.au

I confess the thought of installing a split system that (used propane), with my torch and piston driven vacuum pump, holds little appeal to me.......

"These pr*cks are using these technical committees as a tool for keeping naturals out of their markets."

Industry "watch dogs" that put their own interests ahead of public good? Say it ain't so!
j

Posted By joe.ami on 09 Apr 2010 09:28 AM
I confess the thought of installing a split system that (used propane), with my torch and piston driven vacuum pump, holds little appeal to me.......

Joe,

Your suggestion sounds particularly valid and reasonable to someone unfamiliar with working with flammable refrigerants (or, to be more accurate, refrigerants that are more flammable than current refrigerants). I hear this all the time.

The reality is quite different, however.

Firstly, installing a propane-based split system is made straightforward by any one of a number of approaches. If brazing is required, the only precaution that needs to be observed is to vacuum the system first.

Secondly, regarding vacuum pumps: to understand the matter properly one has to recognise that hydrocarbons are only flammable when the correct ratio of air is mixed with the hydrocarbon (approx 2% - 10% in air). Any other concentration is non-flammable. Secondly, you must have a sufficiently powerful source of ignition.

So, back to the vacuum pump itself: what is it sucking from the circuit? hydrocarbon only. That means the internal volume of the vacuum pump, the suction side lines and all the outlet lines right to the point where the outlet ends, is non-flammable.

Let's take it to an extreme... suppose you are vacuming a propane system and decided to light a match and hold it over the outlet of the vacuum pump. What would happen? You would get a little pop and perhaps a small jet of flame or perhaps a bunsen-burner like continuous flame (depends on the vacuum pump rate and other factors) and that is all. Why? Because the flame cannot propagate back up the lines because further upstream there is no air, therefore no flammable mixture.

This principle of flammability of hydrocarbons is what makes gas burners possible. Similarly, if you take a cigarette lighter to the outlet of an open valve of a propane cylinder, the flame cannot propagate back into the cylinder and cause it to explode. No air.

Ahhh... but what about if some fool has accidentally permitted air to enter into the circuit prior to vacuuming. Firstly, it would need to be a fair amount of air in order to dilute the hydrocarbon to 2% - 10% concentration to cause a flammable mixture, but yes in that case you would have a potentially very catastrophic situation - something akin to a 'pipe bomb'.

BUT - and I can't stress this strongly enough - if the circumstances were repeated with, say, R134a (a common fluorocarbon refrigerant that I'm sure you are aware of), then you would STILL have a pipe bomb on your hands. So called 'non-flammable' R134a is highly flammable when mixed with air above atmospheric pressure. This is not something that the fluorocarbon manufacturers like to publicise much, for obvious reasons.

Also, if brazing around common fluorocarbons, you need to be carefully aware of the potentially lethal toxic fumes that will be produced if the refrigerant or lubricant is exposed to the flame in sufficient quantities. Brazing flames on R12 produce mustard gas (you may recall this as one of the earliest chemical weapons). There are many dead refrigerant technicians giving silent witness to this. If you braze a system and the torch hit's some PAG oil, you're at serious risk.  In contrast, a mineral oil + hydrocarbon system produces no such toxic fumes.

Finally, most countries now prohibit the brazing fluorocarbon systems without first recovering the charge so as to minimise harm to the environment.

So, in summary then, the procedures for safe brazing of hydrocarbon systems are the same as current procedures for brazing fluorocarbon systems, and the explosion risks for both hydrocarbon and fluorocarbon systems are actually very similar.

Additionally, vacuum pumps specifically designed for evacuation of flammable gases are readily available. These models, by design, guarantee the pump is incapable of providing ignition even if a flammable mixture did exist within it.

Posted By joe.ami on 09 Apr 2010 09:28 AM

"These pr*cks are using these technical committees as a tool for keeping naturals out of their markets."

Industry "watch dogs" that put their own interests ahead of public good? Say it ain't so!

Forgive my frustration. We're not the only industry that is on the receiving end of these tactics by monopolists/oligopolists.

Microsoft, big pharma, big banks.... it's all too common these days.

Cheers

John W Clark
Technical Advisor
HyChill Australia Pty. Ltd.
85a Canterbury Rd, Kilsyth, Victoria, Australia
Freecall (aus): 1300 492 445  Ph: +61 3 97285055  Fax: +61 3 97618799
http://www.hychill.com.au

John,  While I admire your enthusiasm for your company's products, and you made many valid arguments, the fact remains that the EPA will not allow flammable refrigerants in many applications.  Here is a good example of the results of defying the rules.  Please note the last paragraph, also.

U.S. EPA ORDERS LAS VEGAS AUTO SHOPS TO STOP USING HC-12A

Release date: 12/18/1996

Contact Information: Dave Schmidt, (415) 744-1578

   (San Francisco) -- The U.S. Environmental Protection Agency (EPA) has ordered six businesses in Las Vegas, Nevada, to cease using the chemical HC-12A  brand hydrocarbon refrigerant blend, a registered trademark of OZ Technology, Inc., as a replacement for the refrigerant CFC-12 (also known as Freon-12) in motor vehicle air conditioning units.  Thesebusinesses include: Econo Lube N' Tune at two Las Vegas locations, Specialized Import Automotive Service, Milford Automotive, Desert Buick-GMC Trucks, Inc, and Sprint Corporation, which services its own vehicle fleet.  

     Production of chloroflourocarbons, or CFC's, was banned by the Clean Air Act Amendments of 1990 because they deplete the ozone layer in the upper atmosphere, which protects living things from harmful ultraviolet radiation.  Vehicle repair shop managers that service motor vehicle air conditioners should be aware that the Clean Air Act requires U.S. EPA to evaluate substitutes for CFC-12 refrigerant to determine whether such substitutes are acceptable, from a health and safety standpoint.  If U.S. EPA determines that a substitute is unacceptable, its use in motor vehicles is illegal.  

     On June 13, 1995, U.S. EPA banned the substance known as HC-12A , a hydrocarbon blend, as a replacement for CFC-12 in motor vehicle air conditioning. U.S. EPA prohibits the use of HC-12A  as a CFC-12 replacement for all uses except industrial process refrigeration.  The ban on HC-12A  covers all types of air conditioning systems.

     Using a flammable refrigerant in a system not designed for that type of refrigerant can be unsafe.  As of this date, the manufacturer of HC-12A , OZ Technology Inc. of Rathdrum, Idaho, has not submitted adequate risk assessment information to EPA to demonstrate the safety of using HC-12A  in automobile air conditioning systems.

     Violation of the order by any of the businesses named could result in assessment of a penalty of up to $25,000 per day of violation.  In addition, a knowing violation may result in a criminal conviction and possibly imprisonment.

This is all any business owner has to know to make a decision about using these refrigerants in a mobile application.  I hope you can win this battle with the EPA, but it won't matter what the public thinks, they are not part of the decision making process.