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Hazardous area classification of diesel engine driven generator

Hazardous area classification of diesel engine driven generator

Hazardous area classification of diesel engine driven generator

(OP)
Dear all
Can anyone tell whether it is compulsory to consider DG Set as a sourse of hazard and hence select a DG suitable for Hazardous area . I am aware that in some countries, due to low flash point of Diesel , this clssification is done and hence DG becomes sourse of Hazard.

Additionally who are the manufactures of this kind of DG set .
Thanks

RE: Hazardous area classification of diesel engine driven generator

I haven't checked the Code lately, but I was involved in a dispute on this issue several years ago.  At that time, there was no classification of anything related to a **diesel** engine-generator set, including the fuel tanks.

Our specifications required an explosion-proof level switch inside the fuel storage tank.  Every bidder took exception to this, saying that this was not required by Code, due to low flammability of diesel fuel, and they were right.  

This may have changed, but at the time, I don't believe there was any requirement to classify anything as a hazardous location.

RE: Hazardous area classification of diesel engine driven generator

Location?  Can't substantiate this but in the US, I believe the IAEI magazine mentioned in passing that Arizona treats diesel oil as Class I, whareas Minnesota does not.  They're both very nice states, but again it’s a case of ‘regional differences/local customs.’  
  

RE: Hazardous area classification of diesel engine driven generator

I do not believe you can buy an XP rated generator.  The operating temperature of the exhaust manifold makes this pretty much impossible.  Even strictly looking at No. 2 diesel fuel, with a flash point of 110 to 336F and an ignition temperature of 410 to 765F, the exhaust manifold could exceed these temperatures.  NFPA makes specific reference to the possibility of a fuel line breaking, squirting fuel onto a hot engine which would fill the room with flammable vapor.

To address this, NFPA typically allows a maximum indoor fuel storage volume of 550 gallons.  Beyond that, the fuel needs to be divided into separate fuel storage vaults (typically with a 3-hr concrete separation?).

The local AHJ will most always have his own interpretation, though.  This is true in both small rural towns and large cities.

RE: Hazardous area classification of diesel engine driven generator

I am not pretty sure about the fuel lines inside the generator and hazard classification. But I am sure that the area of fuel tanks(external),piping from the tank to the generator is considered as a hazardous locations in most of the codes. Therefore electrical wiring and equipment should follow the relevant practices. Nowadays most of these equipments should be INTRINSICALLY SAFE and conduits and other stuff should be selected accordingly.

RE: Hazardous area classification of diesel engine driven generator

Since this subject was originally raised in June, it may be well past the time for an answer.  However I wanted to mention that NFPA 37 (Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines) Article 3-6.2 states, "Engine rooms or other locations shall not be classified as hazardous locations as defined in Article 500 of NFPA 70, National Electrical Code, solely by reason of the engine fuel."

If you have a significant volume of fuel, a common practice is to have a separate fuel tank room, classified as hazardous, or to have the tank outdoors.  However the DG room should not be hazardous.

RE: Hazardous area classification of diesel engine driven generator

As I mentioned previously, NFPA only requires special treatment for the fuel storage area if it is over 550 gallons.

RE: Hazardous area classification of diesel engine driven generator

I know that this is an old posting -- but it did not address one crucial item for a diesel-generator; the regulation of diesel engines is done by varying the amount of fuel injected per cycle -- not by controlling the air intake -- consequently, supplying an additional fuel source (through the intake from the local hazard) may allow the engine to "run away" -- obviously, not an ideal situation in a hazardous location....

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