Explosive zone around pump shaft
Explosive zone around pump shaft
(OP)
Greetings to all.
We have defined Ex zone 1 within inlet pumping station quadratic shaft on WWTP. Flammable gas present is methane. Since shaft cover isn't gas-tight, the Engineer requires that Ex zone 2 needs to be defined around the cover. The shaft is outside the building, i.e. open space is around it.
Is there any exact rule about the shape, position and dimension of zone in this case?
Thanks.
We have defined Ex zone 1 within inlet pumping station quadratic shaft on WWTP. Flammable gas present is methane. Since shaft cover isn't gas-tight, the Engineer requires that Ex zone 2 needs to be defined around the cover. The shaft is outside the building, i.e. open space is around it.
Is there any exact rule about the shape, position and dimension of zone in this case?
Thanks.





RE: Explosive zone around pump shaft
http://www.nfpa.org/catalog/services/onlinepreview...#
Not sure what you are describing, but if you look at the NFPA 820, the area classifications are well defined. One would think that the areas outside of the building will generally be defined as unclassified. The building classifications depend on whether the building is ventilated.
RE: Explosive zone around pump shaft
RE: Explosive zone around pump shaft
Is this a wet well lift station with a vertical pump with the motor mounted above?
What is the capacity? Is this a municipal or industrial wastewater?
Is there a building associated with the pump station, or just the lift station?
RE: Explosive zone around pump shaft
The question is: If there is a Zone 1 under the cover, what is the shape and volume of Zone 2 above the cover? Attached file gives an example, but I don't know on what grounds.
According to Wikipedia, American equivalent to "Zone 1" is "Class I Division 1" and equivalent to "Zone 2" is "Class I Division 2".
RE: Explosive zone around pump shaft
Since the wetwell cover is not sealed, the leakage should be considered to be similar to a vent. A vent has a Class I, Division 1 classification within 3 feet of the vent and Class I, Division 2 classification from 3 feet to 5 feet from the vent.
RE: Explosive zone around pump shaft
But I did not find where the 3m are defined.
Our projects are biogas plants in german, so DIN & EN norms, EU bylaws and their national applications and specific rulings for biogas are relevant.
I don't know if this is helpful in your area.
Where (in what documents) is Ex-protection handled in your neck of the woods? Can you get such a document?
RE: Explosive zone around pump shaft
Thanks for help.
RE: Explosive zone around pump shaft
Over here, the owner/operator of a plant has to supply a statement ("Explosionsschutzdokument") about ex-protextion including detailed drawings ofthe ex-zones. This is necesary to get the permit and is also needed to design external lightning protection etc. I menat, try to get something like this.
RE: Explosive zone around pump shaft