I just stumbled upon this when I was making sure my Royale RM7030 was not part of the two re-calls Dometic had issued:
Dometic RM7030, RM7130 Series Side By Side Cooling Unit (http://www.rvfridgestore.com/dometic-rm7030-side-by-side-cooling-7030.html)
SAFEGUARD Upgrade
SAFEGUARD System Upgrade for Dometic Side by Side Cooling Units.
"If you have heard of the recent recalls by both Dometic and Norcold, then you are aware of the risk of fire due to the chemical contents of the cooling unit....specifically the chemical gas hydrogen that standard cooling units are pressurized with.
The RV Fridge Store has developed a new charge that replaces the hydrogen with a non-flammable inert gas, thus eliminating the risk of fire associated with a possible cooling unit failure. The new gas also has shown to increase the efficiency of the coolant charge."
$150.00
SGU7030
Great info Michael.... ;D
It is probably a helium mixture. I have read that Dometic had done testing and found that it is not as efficient as the hydrogen mix. Atwood makes a helium charged ref.
Michael,
The following test of Helium vs. Hydrogen absorption refrigerator technology goes a long way toward answering your efficiency and cooling capacity questions. It is authored by Roger and Onna Lee Ford.
http://rvrefrigeration.com/wp-content/uploads/Evaluation-Report-rev4.pdf (http://rvrefrigeration.com/wp-content/uploads/Evaluation-Report-rev4.pdf)
Ford's RV Training & Service (Ford's RV) has over 34 years experience in the RV industry. Roger and Onna Lee Ford, the owners of Ford's RV, are pioneers in the RV refrigerator reconditioning industry having designed and are still manufacturing the customized tools required to recondition RV refrigerator cooling units.
Quote from the article:
The marketplace of RV refrigerators over the last 20 years has been dominated by Dometic and Norcold with no other competitors. The introduction of a new competitor, namely Atwood, as well as its use of helium rather than hydrogen, prompted the ownership of Ford's RV Training & Service to conduct a side by side independent evaluation. Absorption refrigeration has used hydrogen since commercial production of absorption refrigerators began in 1923 so the introduction of a new chemical after all this time is a major change. This evaluation was conducted with the expressed goal of determining for the consumer and RV industry how the new helium technology performed relative to hydrogen based absorption refrigerators by putting like models of refrigerators through a series of tests. Every effort was made to ensure that the test products were treated equally by ensuring that conditions for each product were identical.
End Quote.
If all of the "fear-mongering" regarding absorption refrigerators gnaws at your sense of Foretraveling enjoyment, and you do not feel comfortable with the fire detection/suppression devices designed to mitigate the 6% (+/-) chance of an absorption refrigerator fire (if you even experience a fire, from any source, in the first place), helium based absorption refrigerators may offer a safer, slightly more efficient cooling medium at a slightly elevated operating cost. I say "may", because the test compares two different manufacturers and two slightly different designs, so it is not exactly an "apples to apples" comparison.
We just spent several weeks on an extended trip up the east coast with a lot of dry camping involved. I estimate that this trip alone would have added over 120 hours of run time to the generator (catching up the batteries to a high state of charge/reducing the current burdens on the alternator) if we had not been using an absorption refrigerator.
I don't like the thoughts of additional expense/complexity/unsightliness of solar panels/loss of easy roof access, nor the additional wear and tear on batteries, alternator and generator that a residential refrigerator implies. And I wonder if solar panels would have survived that golf ball sized hailstorm that we encountered and if not, would my insurance company have covered the solar panels, if there had been damage?
When considered overall, residential refrigerators violate a whole bunch of "KISS" factors, impose new risks and obviously create a whole lot of additional "related" expenses, even when the entire infrastructure of the installation is well designed and implemented .
To each his own, but think it through carefully, if you are tempted.
Neal
Hmmm... As I understand it RV units use anhydrous ammonia which is flammable in quite low concentrations. It is also explosive in a confined space. There are various theories as to the cause of fridge fires such as the depleted (weak) ammonia/hydrogen gas is what causes the fire. If I read this right substituting helium makes the ammonia non flammable? Chemistry was a long time ago so perhaps someone with actual refrigeration unit experience could weigh in on this
Keith
Keith, The ammonia and hydrogen, which are normally contained within an absorption refrigerator sealed system, are flammable under certain conditions.:
Hydrogen has an auto ignition temperature around 1040° F with flammability limits in air of 7 to 75 percent.
Ammonia has an auto ignition temperature around 1204° F with flammability limits of 15 to 28 percent.
Of note; ammonia starts to dissociate into hydrogen at temperatures above 600° F. If either the hydrogen or ammonia, contained within the sealed system, is released within a flammable range of the above noted percentages, in the presence of a competent, ongoing ignition source (1040 to 1204° F or greater), it is possible for a fire event to occur.
With a vehicle in motion, the concentration ranges would be difficult to achieve and sustain more than momentarily. At rest, any system integrity breech would need to occur simultaneous with concentration and ignition source availability, which also seldom occurs or sustains.
Insurance investigators seem to concur that the largest fraction of the absorption refrigerator related fires occur due to other heat sources creating external stimulus to the absorption refrigerator sealed system breech event.
An example would be fires from other causes, in close proximity to the sealed system, which cause over pressure conditions, which in turn cause the sealed system blow out plug(s) to do their job, releasing system contents in a controlled fashion, preventing a large rupture and explosion. Thus, the sealed system contents may contribute to but are not generally the initial (ROOT) cause of the fire.Using helium vs. hydrogen removes the hydrogen flammability from consideration, but leaves the ammonia.
Lesson: Keeping your mouse nests, insect debris, electrical components and wiring, and fire detection/suppression systems "ship shape", is as, or may be more even more, important than your choice of refrigerator. Neal
Thank you Neal for putting into words the thoughts that have always gnawed at me regarding RV Fridge fires. The minimal gas concentrations levels required for ignition or explosion have always been a question as well as rather high ignition temperature for each component seems pretty safe to me. I had never considered that an overheating situation like from another fire might cause the escape of the pressurized refrigeration gas making it a contributor rather than a cause of an RV fire.
Excellent analysis.
Thanks, Neil.
That's what I was looking for.
Keith
Well,
I sent an inquiry asking for details on this re-charging of a Dometic, and I'm posting that below, and the response I received back a few hours later. So -- it looks like this is no longer an option -- and I'm back to installing a self-contained fire suppression system like many of you have done.
"I have questions regarding your Safeguard upgrade:
SAFEGUARD System Upgrade for Dometic Side by Side Cooling Units.
If you have heard of the recent recalls by both Dometic and Norcold, then you are aware of the risk of fire due to the chemical contents of the cooling unit....specifically the chemical gas hydrogen that standard cooling units are pressurized with.
The RV Fridge Store has developed a new charge that replaces the hydrogen with a non-flammable inert gas, thus eliminating the risk of fire associated with a possible cooling unit failure. The new gas also has shown to increase the efficiency of the coolant charge."
What is It in your charge that substitutes for the ammonia and hydrogen to eliminate the fire risk and yet improve cooling efficiency? Is helium a component?
Has the efficiency gain been independently documented?
And the response:
" I am afraid that you cannot replace or recharge a cooling unit in the field. The tools required are specialized, the new charge must be introduced in a temperature and humidity controled environment to insure the correct ratios of chemicals, etc. Also, our SG charge requires changes to the complete evaporator and boiler assembly to allow for the increased size of the molecules involved....the internal tubing must be larger.
The only way to get the SG is to order a new cooling unit,
Thanks.
Greg
The RV Fridge Store, LLC.
"
Recharging refer cooling units are not field repairable as there has to be a precise amount of all components and pressures Not a do it yourself job.
Hmmm. Larger tubing due to larger molecules? Maybe so, but $150.00 more for the all new helium charged unit vs the rebuilt unit seems like a pretty acceptable tradeoff if it works properly. As far as a temp/humidity controlled environment, I seriously doubt the ammonia charge or the propellant are being exposed to the ambient atmosphere. Like they say, tho, probably not a do it at home job. I was living in Houston in 1976 when the anhydrous ammonia truck ruptured on loop 610. Lots of respect for the stuff. As I recall, no explosion but a toxic cloud that took and ruined the lives of many.
I remember when the Farmer's Market in Tampa burned in the 60's,lot of ammonia explosion's as each cold storage unit became involved, fire department let it burn until there were no more explosion's.