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| Table 1. Exposure Levels and The Human Body. | ||
| Exposure (ppm) | Effect on the Body | Permissible Exposure |
| 50 ppm | Detectable by most people | No injury from prolonged, or repeated exposure |
| 134 ppm | Irritation of nose and throat | Eight hours maximum exposure |
| 700 ppm | Coughing, severe eye irritation, may lead to loss of sight | One hour maximum exposure |
| 1,700 ppm | Serious lung damage, death unless treated | No exposure permissible |
| 2,000 ppm | Skin blisters and burns within seconds | No exposure permissible |
| 5,000 ppm | Suffocation within minutes | No exposure permissible |
Anhydrous ammonia is generally not considered to be a flammable hazardous product because its temperature of ignition is greater than 1,560 degrees F and the ammonia/air mixture must be 16 percent to 25 percent ammonia vapor for ignition.
In spite of the difficulty of igniting such a mixture, never weld on any container or piping that has not been completely decontaminated and cleaned of all ammonia and its salts. Remember, never weld on a closed container of any kind; all containers must be completely cleaned and vented. Apply heat only to open containers, including all piping. Welding should be done only by a welding firm with a type "R" certification in compliance with the North Dakota Century Code.
Anhydrous ammonia contains no water. Anhydrous is the Greek word for "without water." Anhydrous ammonia has a very strong affinity for water. It requires large quantities of water to neutralize its caustic effects on moist areas of the body. When anhydrous ammonia contacts water, it forms ammonium hydroxide. Living tissue is dehydrated quickly and the cells destroyed on contact. Anhydrous ammonia attacks any moist part of the body: eyes, ears, nose, throat, bronchia, lungs, any moist skin. Any tissue containing moisture is chemically burned.
When anhydrous ammonia comes in contact with water, it forms an alkali that chemically burns animal tissue. The chemical burns into the body tissue unless it is diluted by large quantities of water. Anhydrous ammonia is extremely destructive to animal tissue. Skin is reduced to a sticky, gooey substance as the chemical burn progresses. Skin that is chemically burned by the ammonia actually is killed and is not capable of healing or replacing itself. Damaged tissue must be removed surgically so that healing can proceed. The results often are disfiguring.
Anhydrous ammonia causes freezing and chemical burn wherever skin and clothing are moist. The subzero temperature of escaping anhydrous ammonia freezes clothing to the body. Do not attempt to remove any clothing that is frozen to the skin. It must be thawed loose first or skin tissue may be pulled from the victim.
The caustic nature of anhydrous ammonia causes skin and tissue burns similar to burns from heat. Do not apply salves, creams or ointments of any kind to the injury. The caustic burning can be stopped only by dilution with large quantities of water.
Eyes are continually bathed in moisture. Anhydrous ammonia will seek this moisture. The burns will result in damage to the eyes, such as cataracts, glaucoma and possibly some permanent vision loss and disfigurement.
If eyes have been exposed to anhydrous ammonia, they must be flushed with water immediately and continually and the victim must be taken to a doctor immediately. Everyone who works with anhydrous ammonia should carry a 6- or 8-ounce squeeze bottle of fresh water on their person at all times. This small amount of water will last only long enough for the worker to get to a larger quantity of water, but it may make the difference between blindness and sight.
Initially, forcing the victim's eyelids open after the exposure may be necessary. The ammonia trapped under the eyelids must be flushed out with water or it will continue to burn the eye and related tissues.
At low concentrations, the odor of anhydrous ammonia usually will drive the unprotected worker away from the scene. At a higher level of concentration (see Table 2), the worker may not escape without inhaling a dangerous dose. The entire respiratory system is very moist, so anhydrous ammonia will be attracted naturally to that part of the body. When a concentrated level of anhydrous ammonia is inhaled, it will burn the respiratory system quickly. The victim may hurt too much to breathe. The respiratory system essentially may be paralyzed due to the pain.
Table 2. Temperature and Pressure Relationships. Degrees F Pressure (psi) -28 F 0 psi 0 F 16 psi 32 F 48 psi 60 F 93 psi 100 F 200 psi
First-response rescue workers may not be able to treat a serious inhalation exposure. Medical technicians may be able to administer oxygen to aid breathing after their arrival on the scene. Maintaining adequate respiration for the victim until delivery to a medical facility may be difficult.
Respiratory protection is extremely important, but also limited in what equipment is available. A two-cartridge respirator is effective only for exposure levels of less than 300 ppm. Canister type respirators may be effective for longer periods at higher concentrations, but without skin protection, walking through an ammonia cloud is generally not advisable. A self-contained breathing apparatus (SCBA), which supplies the air to be breathed, and a sealed, protective HazMat suit are required for working in a cloud of escaping anhydrous ammonia. Anything less will not sufficiently protect a person in this situation.
Start first aid treatment immediately when someone is exposed to anhydrous ammonia. The chemical burning starts instantly and the injury becomes worse as time passes. Treatment consists of flushing the affected body area(s) with large quantities of water.
One short flushing is not sufficient. Maintain a steady flow of water over the affected area(s) until the victim is delivered to medical help. The water provided with each nurse tank or other container will not be enough. Five gallons flowing in a pencil-sized stream will last approximately seven minutes. Additional water should be carried on every tractor used in field applications and in every field support motor vehicle. Collect as much water as possible and continue flushing while arrangements are being made to transport the victim to a medical facility. Do not reuse the water; it will not provide relief, having already absorbed anhydrous ammonia.
Make arrangements to transport the victim to a doctor or hospital immediately after exposure. First aid can be given while transport arrangements are being made, but get the victim to medical care as soon as possible. Notify the hospital that the victim is being transported. First aid flushing should be continued while in transport.
Clouds of anhydrous ammonia are subject to the unpredictability of air movement; they will change direction as quickly as the breeze. Clouds of ammonia may be nearly invisible in some atmospheric conditions, but they appear as white clouds when the atmosphere is damp. Rain will absorb the ammonia and remove it from the air.
Anhydrous ammonia is heavier than air and will settle in the low areas of the surrounding landscape, such as road ditches, sloughs and valleys. People in threatened areas must be warned of the release and advised to leave the area until the release has been controlled and the area is considered safe for re-entry. These decisions should be made by emergency personnel, such as a local fire department. Animals and livestock should be removed from the threatened area after people have been taken care of first. Most animals will do their best to leave the area long before ammonia concentrations become strong enough to cause them much discomfort.
Due to the seriousness of exposure to anhydrous ammonia, personal protective equipment must be well-maintained. This includes unvented goggles; rubber gloves; respirator; heavy-duty, long-sleeved shirt; and long pants.
The goggles and gloves are to be kept in a safety equipment container mounted on each nurse tank and be accessible from the ground. Having another set readily available on the tractor is an excellent idea. Suitable gloves are made of rubber and are impervious to ammonia, and have long cuffs that should be turned back to prevent drips from running down the arm when hands are elevated. The fit should be loose enough for easy removal but snug enough for good protection.
Goggles must be unvented to keep the anhydrous ammonia away from the eyes. Only the un-vented type of goggles will minimize ammonia exposure to the eyes. Pesticide-type vented goggles are not suitable because ammonia can pass through the indirect vents. Open-vented shop goggles never should be used.
A respirator equipped with anhydrous ammonia cartridges approved by the National Institute for Occupational Safety and Health (NIOSH) is designed only for low-level exposures not to exceed more than 300 ppm. This type of respirator does not have the capacity to protect a person from high-level exposures.
Clothing should be heavy duty and of a tightly woven fabric. Light weight, thin fabrics will not slow down or prevent anhydrous ammonia from passing through. The clothing should be tightly closed at the cuffs and collar to restrict the entry of anhydrous ammonia.
Five gallons of fresh, clean water are to be kept in the emergency water reservoir on the nurse tank and accessible from the ground, according to North Dakota Century Code. Another 5 gallons should be maintained on the tractor for use when the nurse tank water may not be easily accessible or runs out. This water should be changed daily to keep it clean. Dirty water may not flow through the reservoir hose, preventing treatment of the exposure.
Every worker should carry a 6- or 8-ounce plastic squirt bottle in their shirt pocket for the first flushing of the eyes. It should be used immediately and is intended to give the victim time to get to the 5-gallon supply.
Additional protective equipment is required for bulk storage of anhydrous ammonia. A rain suit and two canister-type gas masks are required by law in the North Dakota Century Code (Figure 1). They will protect you only in areas of low ammonia concentrations. A cartridge-type respirator is not approved for use at a bulk storage facility.
Figure 1. Emergency Equipment (for Escape Only) (5KB b&w illustration)
Call the local fire department if a major leak occurs. The fire department has self-contained breathing apparatus (SCBA) and protective suits. SCBA units supply air to breath, rather than just filtering available air. The protective suits are sealed to keep anhydrous ammonia out.
A water reservoir of at least 150 gallons of clean water must be available at a bulk facility, which would enable a person to submerge in water should he or she be exposed to anhydrous ammonia. A minimum 150-gallon stock water tank will meet this requirement.
Keep the informative decals on the equipment up to date. The decals indicate what each system component does and identifies the first aid water, other protective equipment and protective procedures.
Keep the operator's manual for the bulk storage unit in a readily available place for reference when handling the ammonia. Review the instructions when needed.
The bleeder valve is used to bleed or drain pressurized anhydrous ammonia from a closed hose or valve (Figure 2). Opening a bleeder valve will release pressurized anhydrous ammonia slowly to minimize the risk of a sudden release and exposure. Bleeder valves should be opened slowly. Always position yourself upwind or across wind from a bleeder valve to be opened. Never disconnect a nurse tank hose without first draining it with the bleeder valve. Bleeder valves are used in several processes of handling anhydrous ammonia.
Figure 2. Bleeder Valve (3KB b&w illustration)
The nurse tank hose should be inspected daily. It must be maintained in a safe condition since it transfers anhydrous ammonia under high pressure from the nurse tank to the applicator tool bar. Although the hose is protected by an excess flow valve in the liquid withdrawal valve on the nurse tank, the hose must be in good condition to prevent an uncontrolled release (Table 3, Nurse Tank Hose Safety Checklist).
Table 3. Nurse Tank Hose Safety Checklist*
| Nurse Tank Hose | OK | Not OK |
| Cuts or Abrasions | �� | �� |
| Soft Spots/Bulges | �� | �� |
| Blistering/Loose Layers | �� | �� |
| Kinking/Flattening | �� | �� |
| Coupler/Hose Slippage | �� | �� |
| Type of Fittings (correct metals) | �� | �� |
| Current Dated Hose | �� | �� |
| * | If any of these checklist items are "not OK," the nurse tank hose should be replaced. |
| ** | "Anhydrous Ammonia," maximum working pressure, manufacturer's name/trademark, year of manufacture. |
The nurse tank hose must be made of approved materials and braiding, such as rayon, rylon/Kevlar or stainless steel. A hose made with rayon braiding is good for two years from date of manufacture while a hose with nylon/Kevlar is good for four years from date of manufacture and stainless steel is good for six years from date of manufacture (Figure 3).
Figure 3. Nurse Tank Hose (4KB b&w illustration)
The nurse tank hose always should be "parked" or attached to the Acme "parking" fitting on the nurse tank when not in use during the season. Do not drape a hose over any edge that allows the hose to become flat. During the off-season, the hose should be stored in a vertical position, hanging from the shoulder of a coupling in a cool, dry location.
Most hose failures occur within 12 inches of the hose end due to flexing of the hose while attached to the nurse tank or applicator. Select hose fittings that will provide the most support and minimize this type of flexing. Examine the hose carefully before making connections to find problems that may cause a hose failure.
The tank must conform to design guidelines provided by the American National Standards Institute (ANSI). The tank and all of its fittings, including pressure welds, fittings, gauges, hoses, safety valves and metering devices, must withstand a minimum working pressure of 250 psi (Figure 4).
Figure 4 ��� Applicator Tank and Valves (7KB b&w illustration) ��� Nurse Tank and Valves (9KB b&w illustration)
The tank should be painted silver or white to reduce temperatures and pressures resulting from solar heating. Surface defects, such as rust, dents and gouges, reduce the integrity of the tank as a high-pressure container and are not acceptable. North Dakota Century Code specifies that less than 10 percent of the surface may be corroded or missing paint.
The nurse tank hose should have an Acme "parking fitting" to be "parked" on when not in use. The fitting should be installed in such a position that prevents strain on the hose when it is "parked."
The tank must be labeled correctly on each end and side with the green diamond around the words DOT (Department of Transportation) "NON-FLAMMABLE GAS" and on each side and end with "Anhydrous Ammonia" in letters not less than 2 inches high. Safety and first aid instructions must be on the tank. All valves must be identified as to liquid or vapor service.
North Dakota law requires anhydrous ammonia nurse tanks, empty or full, to display either a slow moving vehicle (SMV) sign or a lighted rotating or flashing amber light while on a public roadway. Any vehicle or towed trailer/wagon displaying an SMV sign is restricted to a road speed of not more than 25 miles per hour. Anhydrous ammonia nurse tanks, therefore, cannot be towed at a speed exceeding 25 miles per hour.
The protective equipment kit, containing gloves and goggles, must be attached to the tank and accessible from the ground. The emergency water reservoir also must be attached to the nurse tank and be filled with 5 gallons of clean, fresh water. The water should be changed at least daily because it can absorb ammonia from the immediate environment.
Table 4. Nurse Tank Safety Checklist
| Nurse Tank | OK | Not OK |
| Paint | �� | �� |
| Rust | �� | �� |
| Dents | �� | �� |
| Gouges | �� | �� |
| Parking Fitting for Hose | �� | �� |
| DOT Decals | �� | �� |
| Anhydrous Ammonia Decals | �� | �� |
| Safety Decals | �� | �� |
| First Aid Decals | �� | �� |
| Valve Labeling Decals | �� | �� |
| Slow Moving Sign | �� | �� |
| Safety Kit (gloves, goggles) | �� | �� |
| First Aid Water | �� | �� |
��
[ CONTINUE ]
[ Introduction ] [ Types of Exposure ]
[ Protective Equipment for Anhydrous Ammonia ] [ Nurse Tank Safety Check ]
[ Anhydrous Ammonia Applicator Components ] [ Transport Safety Practices ]
[ Safe Field Practices ] [ Private Stationary Storage Facilities ] [ Farm Transfer Facilities ]
[ Rules for Anhydrous Ammonia Nurse Tank and Storage Container Locks ] [ Summary ] [ References ]
AE-1149 (Revised), August 2008
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North Dakota State University Agriculture and University Extension
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