NEWS for North Dakotans
Agriculture Communication, North Dakota State University
7 Morrill Hall, Fargo, ND 58105-5665

October 21, 1999

Editors: This is the fourth in a series of six articles on Anhydrous Ammonia Safety

Anhydrous Ammonia Breakaway Valve Designed to Give You a Safety Break

A broken hose between a field applicator and an anhydrous ammonia nurse tank is among the most dangerous of farm mishaps. Fortunately, the specially designed breakaway valve nearly always prevents this occurrence.

"That's why it's so important to check the valves often to make sure they're in good condition," says George Maher a safety specialist with the North Dakota State University Extension Service. Every field applicator and nurse tank should be equipped with an emergency breakaway valve. It prevents an uncontrolled release of anhydrous ammonia by separating and stopping the flow of ammonia before excessive tension is placed on the nurse tank hose.

Maher notes that the breakaway valve has a limited lifespan. One manufacturer recommends replacing breakaway valves after three years of service. "Some ammonia additives shorten the safe service life of some rubber and metal parts," he says. "So frequent inspections are important."

If the breakaway valve is working properly and the nurse tank hitch pin fails, the breakaway valve will pull apart, automatically stopping the flow of anhydrous ammonia from the nurse tank hose.

Following safety precautions are important when reconnecting the nurse tank to the field applicator, Maher says. Here is the recommended procedure:

1. Put on the protective gloves and goggles and have emergency water directly available. Never work on anhydrous ammonia equipment without them.
2. Be sure anhydrous ammonia is not escaping from the hose end.
3. Close the liquid withdrawal valve on the nurse tank and then the nurse tank hose end valve.
4. Open the bleeder valve on the nurse tank hose and bleed off the ammonia trapped between the breakaway valve and the nurse tank hose valve. Also open the bleeder valve on the manifold. Leaving ammonia under pressure in these locations can make reattaching the hose dangerous.
5. Inspect the nurse tank hose and manifold for damage suffered in the pull-apart. Replace as necessary.
6. Reattach the nurse tank to the applicator and safety-clip the hitch pin in place.
7. Close all the bleeder valves that were opened.
8. Connect the nurse tank hose to the manifold and open the nurse tank hose valve to repressurize the system.

If the breakaway valve is not present or fails to operate correctly and a nurse tank hose is broken, anhydrous ammonia will gush from the broken end of the nurse tank hose. "This is an extremely dangerous situation," Maher emphasizes. "As expensive as it could be, it may be advisable to let the ammonia flow from the nurse tank until the tank is empty. This is an option only in an unpopulated area. In a populated area, call the fire department and let them control the situation. Also, alert everyone in the vicinity, especially those downwind, to the ammonia hazard and urge them to evacuate."

Only those equipped with a self-contained breathing apparatus and fully protective rubber suit should attempt to wrestle with the nurse tank hose in an attempt to gain control. "Trying to do that on your own without proper equipment can cost you your life," Maher says.

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Source: George Maher (701) 231-8288
Editor: Tom Jirik (701) 231-9629