Ammonia / Hydrogen classification

[wdnaylor]

We are having to classify our ammonia "cracker" facility to comply with EPA and OSHA regs. We receive ammonia via truck to fill a large tank. The ammonia is then heated to break it apart into hydrogen (75%) and nitrogen (25%). The whole process takes place outdoors away from the main building. The hydrogen is then piped into our furnaces inside the building. There are no vents or relief valves inside until the furnaces. There are other safety measures to prevent accidental release. There are burn offs from the furnaces and positive pressure inside the room, as well as exhaust fans. The installation has been in place for >20 yrs. Will we need to classify any of this area (it is not currently classified and none of the electrical equipment is explosion proof), and do we need to have a licensed engineer to sign off on this?
By reading previous posts is sounds like we may be able to rely on past experience and declassify it according to NFPA 497 3.3.1 and 3.4.4

 

[rbalex]

Re: Ammonia / Hydrogen classification

From the way you're stating it, I assume the process itself is unchanged and you are simply documenting it for Process Safety Management purposes.

There are no electrical area classification issues with the process as you have described it; however you may need to consult with ANSI K61.1, American National Standard Safety Requirements for the Storage and Handling of Anhydrous Ammonia for other potential issues.

 

[wdnaylor]

Re: Ammonia / Hydrogen classification

Thank you for your help.
Is your major reason for not classifying the area due to the time of the installation, or maybe other measures?
I think that it would be a combination of the two, but I will need to backup my answer.

 

[rbalex]

Re: Ammonia / Hydrogen classification

You cited the correct Sections in your original post.

As you have described it, if this were the original installation, I would not apply electrical area classification per 3.3.1(a) and (b) and 3.3.3 in the vicinity of the furnaces. Section 3.4.4 simply strengthens that position.

Edit Add; I should have said. "... if this were a NEW installation..."

[ April 11, 2005, 07:20 PM: Message edited by: rbalex ]

 

[john m. caloggero]

Re: Ammonia / Hydrogen classification

When I worked in industry, we installed an electric ammonia disassociator to generate hydrogen for heat treating coil and motor laminations. The room was provided with ventilation with roof vents, so that any hydrogen would be vented to the atmosphere, since hydrogen was very light and dissipated rapidly. Vent openings were provided at the lower parts of the room so that natural air convection would occur. The greatest danger was from leakage of ammonia. The electrical wiring equipment within the room was not designed for a hazardous (classified)location. It operated for over 15 yrs that I was there with out any incidents.