wiring ammonia refrigerant plant

[EEuno]

I am trying to find out what the wiring requirements are for an industrial ice manufacturing plant using ammonia as a refrigerant. The vendor seems to think no special "hazardous" methods apply. Any other thoughts??

 

[davidbeach]

Probably depends on the applicable codes, which depends on where in the world you might happen to find yourself.

 

[electricuwe]

I guess in this case the main concern that should be taken care of is that ammonia is a quite poisonous gas whereas I wouldn't be afraid of explosion or fire.

 

[resqcapt19]

While ammonia is classified by the DOT as a non-flammable commpressed gas, it is flammable and can form an explosive mixture with air in the event of a leak. There have been a number of serious explosions in ice cream plants and other facilities that use ammonia as the refrigeration gas. The following is the Informational Note (formally known as Fine Print Note) for Section 500.6(A)(4) in the NEC.

Informational Note No. 2: For classification of areas involving ammonia atmospheres, see ANSI/ASHRAE 15-1994, Safety Code for Mechanical Refrigeration, and ANSI/CGA G2.1-1989, Safety Requirements for the Storage and Handling of Anhydrous Ammonia.

 

[waross]

Ammonia does burn. There have been several large plant completely destroyed when an ammonia leak lit up.
I had a personal experience when leak testing a large ammonia system. The systems are leak tested with a burning sulfur stick. Leaks are indicated by clouds of white smoke. I encountered a hole in a welded joint and the ammonia lit up into a flame about 12 inches long. Yes, DOT to the contrary, ammonia DOES burn.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[resqcapt19]

The issue is the definition of flammable gas used by the DOT. To meet their defintion the LEL has to be 13% or less. The LEL of ammonia is 16%.

 

[controlsdude]

. 29 CFR 1910.111 Storage and handling of anhydrous ammonia
This standard covers the design, construction, location, installation, and operation of anhydrous ammonia systems including refrigerated ammonia storage systems. Ammonia manufacturing plants and refrigeration plants where ammonia is used solely as a refrigerant are, however, not covered.

When I did freezer and chillers Material Handling Equip, I know the ammonia cooling had alarms on it in case of leaks. And it was common practice that you took these seriously due to the burn hazards chemical and fire dangers.

But as far as wiring, it was always a concern of 24vdc working in low temperatures, mainly if your using distributed networks. So basically all the wiring into the freezer areas (-20f) was 120vac. Any other areas could be distributed networks if above 0f. The control panel for freezers was located in a heated area.

Biggest concern was always the right type of oil in gearboxes. No pneumatics being used in freezers. Just common sense items.

 

[Zogzog]

I would also be concerned about the chemical reaction with ammonia and copper becoming an issue.