Originally Posted by mel s
mrt_1111 and anotherone
I would also like to see those "engineering reports".
I find it hard to believe that any RV refrigerator ever "exploded and caused a fire when it was totally disconnected and turned off not being used.
Is that information in those "engineering reports" also?
I am not an engineer, nor am I an expert on this subject, therefore I offer no opinions other than my own.
However engineering experts have been commissioned to study this matter extensively. The attorneys in our case have retained the services of recognized industry experts to study this subject and then document the facts in scientifically documented reports that can be submitted as expert testimony.
I do not believe that it would be proper for me to submit the entire sworn statement of the experts in this matter that have been submitted regarding Norcold refrigerator fires, however I am submitting specific passages of the testimony submitted to the court below:
A penetration in the boiler initially allows the weak ammonia solution to leak out, but when the level gets below the penetration, the hydrogen gas in the system will escape
. The National Fire Prevention Association (NFPA) defines this leakage as fugitive gas. Since hydrogen gas Is very flammable
with a broad flammability range, mixing it even with a small amount of air will product a flammable mixture. All that is needed is a competent ignition source co cause a fire.
For the ******* refrigerator, Norcold had implemented several changes/recalls to eliminate competent ignition sources by shutting down the refrigerator, but not solve the root problem of the corrosion causing the leak. The ***** refrigerator had the most recent recall performed, that is the installation of a High Temperature Sensor (HTS). Norcold’s own incident report documents, however, show that fires involving Norcold refrigerators are still occurring even though the HTS is installed, demonstrating that shutting down the refrigerator does not eliminate all ignition sources for hydrogen gas.
It should be noted that the methods used for installation of the refrigerator is not gas tight and entry into the living space of the hydrogen gas is possible.
The date suggests that there is an increase in ignition sources capable of causing combustion during a hydrogen release as compared to other flammable gasses. Further, they discussed several postulated mechanism of spontaneous ignition during the pressurized hydrogen release. Several are pertinent to the release of hydrogen gas from a Norcold cooling unit. First, hydrogen has a reverse Joule-Thompson – meaning the temperature of the gas will increase when it is released from high pressure to ambient. Second, the hydrogen reaches high velocities with particles present which can because electrostatic discharge.
Dyer, et al., found sudden releases “can result in multi-dimensional transient flows involving shock formation, reflection and interactions” resulting in combustion. The conditions for spontaneous combustion similar to those studied by Dryer may be set up by the geometry of the boiler tube/heater pocket area and the area of hydrogen gas discharge common to Norcold gas absorption refrigerators, including the ***** refrigerator.
Summary from engineering / expert expert witness declaration:
From the above discussions, I hope the following opinions:
• The leak in the boiler tube in the ***** refrigerator cooling unit was caused by corrosion, from the inside of the boiler tube out. This is the common failure mechanism seen on Norcold refrigerators and he subject of their various recalls. It is consistent with the Norcold cooling unit being the cause of the ****** fire.
• Shutting down the refrigerator electrically does not eliminate all ignition sources for hydrogen gas because of the many possible ignition sources.
• Spontaneous combustion of the escaping hydrogen gas from the cooling unit cannot be discounted as the source of ignition for the ****** refrigerator fire.
Based up conversations I have had with knowledgeable persons, Norcold refrigerators can have boiler leaks when running on either electric or gas. It also can occur when the refrigerator is totally shut off and disconnected from a power source.
If you read the information about from the report that was generated, it indicates that the high pressure discharge of the hydrogen gas can achieve spontaneous combustion through particulates that can be present in the air - e.g. potentially fragments of insulation dislodged as a result of the escaping hydrogen and ammonia.
Hopefully that information answers the questions / doubts that you had regarding this issue. As I said, this isn't my information. It is information provided as expert witness testimony / statement.