Class 1 Div 1 enclosures

[BakerRD]

Dear All,
We are a company making engine/generator protection modules. I'm looking for a class 1 div. 1 enclosure. The cover needs to be see through to view my module. Does any one have the name of a manufacture they could recommend? Appleton and Hoffman did not seem to have this type of enclosure. I have seen them on applications on drilling platforms but could not read a manufactures name. Any idea? Thanks.

 

[petersonra]

Re: Class 1 Div 1 enclosures

there are several companies that make a window kit that can be instaleld in an explosion proof enclosure.

appelton and coruse-hinds come to mind.

 

[rbalex]

Re: Class 1 Div 1 enclosures

Appleton is one of the EGS group of companies; OZ/Gedney is another and they tend to have more of the "exotic" HAZLOC application enclosures. You can contact them here.

 

[don_resqcapt19]

Re: Class 1 Div 1 enclosures

I don't really understand how the area around an engine generator would be Class I, Div 1. It is very unlikely that the electrical parts of the engine meet this classification.
Don

 

[rbalex]

Re: Class 1 Div 1 enclosures

In general I'd agree with you Don; especially if we had specified the fuel was diesel. But it wasn't.

Depending on the size, fuel delivery method and possibly if there is a HRSG involved, it may be prudent to classify certain areas near natural gas systems.

Since none of that was specified, I simply answered the question asked.

 

[don_resqcapt19]

Re: Class 1 Div 1 enclosures

Bob,
What is HRSG?

 

[rcwilson]

Re: Class 1 Div 1 enclosures

Originally posted by don_resqcapt19:
Bob,
What is HRSG?

Usually it is a Heat Recovery Steam Generator, placed on the exhaust of a gas turbine engine to generate steam from the exhaust heat. Like a boiler except it runs on hot air (like us engineers). HRSG's are prevalent in combined-cycle power plants. Steam is used to operate a steam turbine generator to increase the plant?s total efficiency.

An HRSG is just a big air duct with water/steam tubes in it. The turbine exhaust has enough oxygen to support combustion, so some HRSG's have auxiliary natural gas burners to add heat and boost the steam output. These "duct burners" mean there is natural gas in the area, possibly leading to a Class 1 Div 2 classification. However, there is a lot of discussion about whether the duct burner by itself is reason to classify an area. (I don't think it is.)

On the original question about windows in NEMA 7 enclosures: Depending on the size of the window needed it may be best to go to a purged enclosure. It may be difficult and expensive to get a NEMA 7 style enclosure with a window large enough to see the controls.

BTW, I have seen several engine controls that were in Class I Div 1 areas, usually in gas compressor stations, offshore oil rigs, or pipeline pumping applictions.

Bob Wilson

 

[justdavemamm]

Re: Class 1 Div 1 enclosures

http://www.killark.com/ EXB Series enclosures for Class I Division I non-purged enclosures up to 24" x 36" can be ordered with windows up to 5" x 9".

 

[rbalex]

Re: Class 1 Div 1 enclosures

Bob Wilson did a find job describing a HRSG, although from my petrochem background I tend to think of them as auxiliary fired heaters because we may often use the steam as process steam rather than in combined cycle generation (although we may do both.) Where we do use all or part of it for straight process purposes we often need to have an additional heat source when the generators are not in operation and a HRSG may operate more or less as a conventional fired heater. API has altered their view on ?non-electrical ignition sources? around fired heaters a bit.

From API RP500:

6.2.4.3 The practice of not classifying locations where non-electrical ignition sources (e.g., the open flame of an unprotected fired vessel or flare tip) exist has been utilized in previous issues of RP 500. It is recommended that the application of this practice be limited to unprotected fired vessels or flare tips and that the resulting unclassified locations be restricted to their immediate vicinity. Electrical equipment located in these unclassified locations typically is de-energized for the majority of the time that the flame source is not present.

Note: Although from a practical view, when an open flame is present, a spark from electrical equipment in the immediate area of the flame would not likely be the initiator of combustion, the location of sources of ignition is not a criteria[sic] for the classification of locations. Classification is, by definition, based on the likelihood of the presence of flammable mixtures. It is not the intent of this document to recommend the creation of an unclassified location in which one can locate general purpose electrical devices that are not directly associated with the combustion or ignition systems of unprotected fired vessels or flare tips.

Several gas metering an HRSG manufacturers also specifically recommend classification around their equipment, so it?s ?prudent? in any case.