North Dakota State University
NDSU Extension Service

Anhydrous Ammonia: Managing The Risks

AE-1149, August 1998
George G. Maher, Ag Safety Specialist

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
Summary
References

Introduction

More anhydrous ammonia is used as fertilizer in North Dakota than any other nitrogen fertilizer source. Anhydrous ammonia is classified as a hazardous substance. Most accidents with anhydrous ammonia are due to uncontrolled releases. Few problems occur when the ammonia is being handled and applied as intended. Most uncontrolled releases are due to improper procedures, careless or untrained workers, or faulty equipment. Protective equipment is required by law to be available where anhydrous ammonia is handled or applied. Wearing protective equipment greatly reduces the chance of injury from an ammonia release. Countless tons of anhydrous ammonia are applied every crop year without problems; safe procedures and quality equipment do work.

Anhydrous ammonia has the potential to be one of the most dangerous chemicals used in agriculture today. It is used and stored under high pressures, which requires specially designed and well-maintained equipment. Those who work with anhydrous ammonia must be trained to follow exact procedures in handling it.

Chemistry of Anhydrous Ammonia

Ammonia is a chemical compound used as a fertilizer because it is rich in nitrogen. Its formula is NH₃, which means that it consists of one atom of nitrogen and three atoms of hydrogen per molecule. Because the atomic weights of nitrogen and hydrogen are not the same, the weight ratio is 82.5 percent nitrogen and 17.5 percent hydrogen. Anhydrous means the ammonia is without water. This distinguishes it from ammonia/water solutions.

Characteristics of Anhydrous Ammonia

Odor

Anhydrous ammonia is a clear, colorless gas at standard temperature and pressure conditions and has a very characteristic odor. The odor is the strongest safety feature of the product. At only 50 parts per million concentration, one sniff tells what is in the air. Normally, the odor will drive a person away from the area. A concentration of more than 5000 parts per million will disable a person so that escape is impossible and suffocation results.

Pressure for Storage

Anhydrous ammonia is a liquid when compressed or cooled. It is stored under pressure to prevent vaporization so a large volume can be available for use. One cubic foot of anhydrous ammonia in a liquid state produces 855 cubic feet of ammonia gas. Retail storage tanks and nurse tanks for anhydrous ammonia are built to withstand internal pressures of at least 250 pounds per square inch (psi). Terminal storage tanks refrigerate ammonia to minus 28 degrees F. At this temperature, the storage pressure is less than 1 psi.

Temperature/Pressure Relationships

When anhydrous ammonia is released from compression in a storage tank (200 psi) to the atmosphere (0 psi), the temperature drops from 100 degrees F to minus 28 degrees F. At this temperature, ammonia will freeze-burn the skin on contact. Clothing is actually frozen to the skin. Another risk is that ammonia when released will quickly expand from the point of release. A suddent rupture can shoot ammonia 10 to 20 feet from the point of release.

Table 1. 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

Flammability

Anhydrous ammonia is generally not considered to be a flammable hazardous product. Its temperature of ignition is higher than 1560 degrees F, making it rather difficult to ignite. The ammonia/air mixture must be 16 to 25 percent ammonia vapor.

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. Then, the welding can be done by a welding firm with a type "R" certification in compliance with the North Dakota Century Code.

Anhydrous

Anhydrous ammonia contains no water. Anhydrous is the Greek word for 'without water.' When anhydrous ammonia contacts water it forms ammonium hydroxide. Living tissue is quickly dehydrated and the cells destroyed. It attacks any part of the body that is moist—eyes, ears, nose, throat, bronchia, lungs, any moist skin. Any tissue that contains moisture is chemically burned.

Caustic Nature

Anhydrous ammonia forms an alkali when in contact with water, and it chemically burns animal tissue. The chemical will burn its way into the body unless it is diluted by vast quantities of water. Anhydrous ammonia is extremely destructive to animal tissue. The skin is reduced to a sticky, gooey substance as the chemical burn progresses. Skin that is chemically burned by the ammonia is actually killed and is not capable of healing or replacing itself. Damaged tissue must be removed by a medical doctor so that healing can proceed. The results can often be disfiguring.

Types of Exposure

Anhydrous ammonia has a very strong affinity for water. It requires vast quantities of water to neutralize the caustic effects of anhydrous ammonia on moist areas of the body. Such areas include the eyes, breathing system (mouth, throat, bronchial tubes, lungs), and especially moist skin (skin which is damp from perspiration; arm pits, groin, forehead, scalp, feet).

Skin

Anhydrous ammonia will cause freezing and chemical burn wherever the skin and clothing are moist. The sub-zero temperature of escaping anhydrous ammonia will freeze 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 will cause 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 only be stopped by dilution with large quantities of water.

Eyes

The eyes are continually bathed in moisture. Anhydrous ammonia will seek out this moisture. The burns will result in damage to the eyes such as cataracts, glaucoma, and possibly some permanent vision loss and disfigurement.

If the eyes have been exposed to anhydrous ammonia they must be immediately and continually flushed with water and then victim 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, it may be necessary to force the victim's eyelids open after the exposure. The ammonia trapped under the eyelids must be flushed out with water or it will continue to burn the eyeball and related tissues.

Lungs

At low concentrations the odor of anhydrous ammonia will usually 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 naturally be attracted to that part of the body. When a concentrated level of anhydrous ammonia is inhaled it will quickly burn the respiratory system. It may hurt too much to breathe. The respiratory system may essentially be paralyzed due to the pain.

Table 2. Exposure Levels and The Human Body

-------------------------------------------------
Exposure   Effect on 		Permissible 
(ppm)	   The Body		Exposure
-------------------------------------------------
50 ppm     Detectable by most 	No injury from 
	   people		prolonged, or
				repeated exposure

134 ppm    Irritation of nose 	Eight hours, 
	   and throat		maximum exposure

700 ppm    Coughing, severe 	One hour, 
	   eye irritation,	maximum exposure
	   may lead to loss
	   of sight

1700 ppm   Serious lung 	No exposure 
	   damage, death  	permissible
	   unless treated

2000 ppm   Skin blisters and 	No exposure 
	   burns within 	permissible
	   seconds

5000 ppm   Suffocation within 	No exposure 
	   minutes		permissible
-------------------------------------------------

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 to the scene. It may be difficult to maintain adequate respiration until delivery to a medical facility.

Respiratory protection is extremely important but also limited in regard to what equipment is available. A two-cartridge respirator is only effective for exposure levels of less than 300 parts per million. 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.

First Aid Calls For Water + Water + Water

When someone is exposed to anhydrous ammonia start first aid treatment immediately. The chemical burning starts instantly and the injury becomes worse as time passes. Treatment consists of flushing the affected body area(s) with lots 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 only 7½ minutes. Additional water should be carried on every tractor used in field application and every field support motor vehicle. Collect as much water as possible and continue flushing while arrangements are being made for transportation to medical help. Do not reuse the water; it will not provide relief, having already absorbed anhydrous ammonia.

Transport To Medical Facility

Make arrangements to transport the victim to a doctor or hospital immediately after the 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.

Uncontrolled Releases

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. Ammonia vapors may pose a threat to farm houses and other residences. 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 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.

Protective Equipment for Anhydrous Ammonia

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, accessible from the ground. It is an excellent idea to have another set readily available on the tractor. Suitable gloves are made of rubber, are impervious to ammonia, and have long cuffs which 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 should never 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 parts per million. They do 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 immediate flushing of the eyes. It is to be used for the first flushing of the ammonia from the eyes and is intended to give the victim time to get to the 5 gallon supply.

Protective Equipment For Bulk Storage Facilities

Additional protective equipment is required for bulk storage of anhydrous ammonia. A rainsuit 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)

If a major leak should occur, call your local fire department. They have self-contained breathing apparatus (SCBA) and protective suits. The SCBA supplies the air the wearer breathes, and not simply filter it as the respirators (cartridge and canister types) can only do. The protective suits are sealed to keep out anhydrous ammonia.

A water reservoir of at least 150 gallons of clean water must be available at a bulk facility location, which would enable a person to submerge in water should they be exposed to anhydrous ammonia. A stock water tank will meet this requirement.

Keep the informative decals on the equipment up to date. These decals tell what each system component does and identifies the first aid water and protective measures.

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.

Nurse Tank Safety Check

Bleeder Valves

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)

Nurse Tank Hose

The nurse tank hose is subject to a lot of abuse, so it must be inspected on a daily basis. It must be maintained in safe condition since it transfers anhydrous ammonia under high pressure from the nurse tank to the applicator toolbar. 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*

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 2 years from date of manufacture, with nylon/kevlar for 4 years from date of manufacture, with stainless steel for 6 years from date of manufacture (Figure 3).

Figure 3. Nurse Tank Hose (4KB b&w illustration)

The nurse tank hose should always 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 flatten out. 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 from 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 which may cause a hose failure.

Nurse Tank

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.

There should be an Acme "parking fitting" for the nurse tank hose 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 correctly labeled on each end and side with the green diamond , DOT "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 kit must be complete with protective gloves and goggles. 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

North Dakota State University
NDSU Extension Service

Anhydrous Ammonia: Managing The Risks (continued)

AE-1149, August 1998

Nurse Tank Safety Check (continued)

Nurse Tank Gauges and Valves

Regularly scheduled maintenance must be conducted to ensure that the gauges and valves on a nurse tank are suitable for service. The degree of hazard increases as these parts get older. A visual inspection should be completed before each use.

Some nurse tank components have a service life limitation based on time. The service life cannot be extended. Use a checklist to prevent missing items. A suggested checklist is provided in Table 5, Nurse Tank Valve and Gauge Safety Checklist. When a component is found to be defective, it must be repaired or replaced.

Table 5. Nurse Tank Valve and Gauge Safety Checklist*

* If any items are marked "Not OK," they should be replaced.

The liquid withdrawal valve (Figure 4), connects the nurse tank hose to the interior of the nurse tank for removal of the ammonia. The intake for this valve reaches nearly to the bottom of the tank so that liquid ammonia will be withdrawn until the tank is nearly empty. It contains an excess flow valve which prevents anhydrous ammonia from flowing out of the tank too quickly, such as if the nurse tank hose had broken (Figure 5). The excess flow valve has a five-year replacement requirement.

Figure 5. Excess Flow Valve (3KB b&w illustration)

The liquid fill valve (Figure 4) is used in the process of filling the nurse tank from a bulk storage facility. It also has an excess flow valve which prevents anhydrous ammonia from flowing back out of the nurse tank if a major release were to happen in the tank filling line or hose. There is a five year replacement requirement on this valve, too.

The pressure gauge (Figure 4) indicates the interior pressure of the nurse tank in pounds per square inch (psi). This indication of interior pressure is affected by the quantity and temperature of the anhydrous ammonia in the tank. The pressure gauge does not have a limit to its service life, but attention should be given to its accuracy and smoothness of operation. Replace it when it appears to be faulty.

The fixed liquid level gauge is a bleeder valve with a tube extending into the tank to a depth where the tank would be 85 percent full of liquid (Figure 6). The valve should be partially opened when the tank is being filled, the operator being careful to never be downwind of it. It will bleed off, or spurt, liquid anhydrous ammonia when the tank becomes 85 percent full. The gauge is most accurate when the nurse tank is in a level position, front to back and side to side. Do not continue filling the tank after the valve releases liquid anhydrous ammonia.

Figure 6. Fixed Liquid Level Gauge (4KB b&w illustration)

The vapor return valve is used in the process of filling the nurse tank at a bulk storage facility. As liquid anhydrous ammonia is transferred into the nurse tank the vapor in the nurse tank must be moved to the bulk storage tank to allow for the incoming liquid. The vapor valve has an excess flow valve (with a five-year replacement requirement). The excess flow valve will stop the release of anhydrous ammonia vapors from the nurse tank in the event of the vapor valve failing.

A hydrostatic relief valve should be used anywhere anhydrous ammonia may be trapped in any section of the liquid or vapor lines of the system (Figure 7). It opens at 365 psig to relieve excess pressure due to liquid expansion.

Figure 7. Hydrostatic Relief Valve (2KB b&w illustration)

The liquid level float gauge indicates the level of liquid anhydrous ammonia in the tank. It works with mechanical components to show the liquid level and uses a needle pointer on the gauge (Figure 8). The fixed liquid level gauge (Figure 4) should be used to determine the 85 percent full level when filling the tank, do not use the liquid level float gauge.

Figure 8. Float Gauge (3KB b&w illustration)

The safety relief valve is also known as the pressure-relief valve. This valve is located on top of the tank (Figure 4) and prevents excessive pressure from building up in the tank due to overfilling or expansion from heat (Figure 9). The valve opens directly to the atmosphere at pressures of 250 to 265 psi. It closes when the interior pressure drops below 250 psi. It must be replaced every five years if it has non-metallic seats and tested every five years in lieu of replacement if it has metallic seats. Repairs can only be done by a repair organization with a valid "VR" certificate of authorization from the national board of boiler and pressure vessel inspectors. This valve must have a rain cap in place to prevent damage from moisture and corrosion. The safety relief valve is not adjustable and should be replaced if found to be inoperable.

Figure 9. Pressure-Relief Valve (4KB b&w illustration)

The rotary gauge (Figure 10) mounted on the end of an anhydrous ammonia tank, bulk tank, nurse tank or applicator tank consists of a dip tube inside the tank and a bleeder valve. This gauge is used to determine the actual level of anhydrous ammonia in the tank. It is accurate only when the tank is positioned level, side to side and end to end. Once the bleeder valve is opened, the knob is rotated to the point where liquid spurts from the bleeder valve and the indicator shows the liquid level in the tank.

Figure 10. Rotary Gauge (3KB b&w illustration)

Back check valves (Figure 11), are part of the bulk storage facility, not a nurse tank or applicator tank. It is used to control the direction of flow of anhydrous ammonia when unloading a truck or rail tank car, preventing a flow of anhydrous ammonia from the bulk tank to the truck or rail tank car being unloaded. A flow in the wrong direction causes the valve to snap shut. It will open only when the direction of flow is correct.

Figure 11. Back-Check Valve (3KB b&w illustration)

The emergency shut off valve is another valve not found on a nurse or applicator tank (Figure 12). As another part of the bulk storage facility, it stops the flow of anhydrous ammonia when the operator of the facility detects an emergency situation and decides to stop the transfer of anhydrous ammonia immediately. This valve is located on the discharge side of the transfer pump.

Figure 12. Emergency Shut Off Valve (6KB b&w illustration)

The roll cage for gauges and valves protects those parts if the nurse tank should roll over. The roll cage must be strong enough to prevent damage to the gauges and valves.

Do not attempt makeshift repairs. All repair or service work on these components must be completed by a qualified technician with experience and training in such work.

Nurse Tank Running Gear

The nurse tank running gear is subject to considerable abuse. When using a nurse tank from a vendor it is usually unknown who used it previously and how carefully it was handled. The running gear should be inspected before each use to be sure it is roadworthy and will work in the field without failure. Refer to Table 6 for a suggested safety checklist.

Table 6. Nurse Tank Running Gear Components

The use of a safety clip on the hitch pin when towing anhydrous ammonia nurse tanks on and off the road is essential to your safety and that of the public. The safety clip will keep the hitch pin from working out and releasing the nurse tank.

Always attach safety chains when towing anhydrous ammonia nurse tanks on public roads. Safety chains are required by North Dakota law. The chains help ensure that the vehicle towing the nurse tank will remain in control of the nurse tank should the hitch pin fail. The driver of the towing vehicle is completely responsible for whatever happens if the nurse tank becomes separated from the towing vehicle. If you can keep the nurse tank on the road, in your lane and bring it to a safe stop, you can probably avoid a more serious accident.

All of the lug nuts are needed to keep a wheel rim on the hub. Using the wheel without the full set of lug nuts adds strain to the remaining lug nuts, causing them to fail sooner than otherwise. The lug nuts also need to be tight to do the job. If one is loose, the others may also become loose.

Check the tires each time the nurse tank is to be used, because a sudden flat tire can cause an accident. Watch for cuts, bruises, and tread wear while regularily checking the tire pressure. Tires used on nurse tanks are designed for only low speed travel, not to exceed 25 mph. Follow the restricted speed requirements for anhydrous ammonia, on or off the road.

Inspect the nurse tank wagon frame every time before pulling it on the road or in the field. It carries a heavy load and is often subject to uneven terrain in the field. Watch for cracks, broken welds, and bent members. The bolts and nuts which attach the tank to the frame are especially subject to loosening or breaking. The main stem of the frame connecting the front to the rear commonly breaks where there are bolt holes near the ends.

Wheel bearings should be checked and repacked on an annual basis. Steering systems should be checked and lubricated as needed to work safely. If either is sticky and not performing correctly, do not continue to use the nurse tank without correcting the problem. A nurse tank with loose and wandering steering or a nurse tank that does not turn when it should or does not recover from a turn is a hazard and should not be used, on or off the road.

The nurse tank must be securely attached to the wagon frame. A tank filled with anhydrous ammonia must be kept in control. If it should separate from the wagon frame there will be serious safety problems. While inspecting the nurse tank, it takes only a few seconds to see that the tank is secure on the frame.

Anhydrous Ammonia Applicator Components

A very important development in anhydrous ammonia safety is likely to be the breakaway coupler (Figure 13). It is designed to prevent an uncontrolled release when a nurse tank releases from the applicator and the nurse tank hose pulls in two. A spring loaded valve closes when the coupler separates from the main body to prevent anhydrous ammonia from flowing out of the hose or the applicator. The breakaway coupler is dated and has a service life of three years, after which it must be replaced. The replacement date is stamped on the coupler.

Figure 13. Breakaway Coupler (5KB b&w illustration)

To reconnect the breakaway coupler, certain steps must be completed in a definite order.

1. Put on the gloves and goggles from the emergency kit on the nurse tank. Check the availability of emergency water reservoir; be sure it is there.
2. Check the wind direction. Always stand upwind when handling ammonia equipment so that ammonia vapors blow away from you, not toward you.
3. Pick up the hose from the ground and place it on the tank or applicator so it is not in the way when reattaching the nurse tank and the applicator.
4. Make necessary hitch repairs or replacements and reattach the nurse tank to the applicator, using a safety clip on the hitch pin and the nurse tank safety chains.
5. Close the nurse tank liquid withdrawal valve, nurse tank hose valve and the applicator flow meter. Failure to close any of these valves may result in a dangerous spray of ammonia.
6. Point the hose end away from you and close the hose end valve. Point the bleed hole away from your face and slowly open the bleeder valve.
7. Stand so that your face is away from the opening of the bleeder valve on the breakaway coupler. Slowly open the bleeder valve on the breakaway coupler unit. Keep the bleeder valves open until all reconnections have been made. Liquid ammonia in the hose can vaporize and pressurize the hose after the hose valves are closed.
8. Open the applicator flow meter shutoff valve to prevent pressure from building in the applicator flow meter system.
9. AFTER the ammonia has been drained from the hose and breakaway coupler body, clean all soil and debris from the hose end and breakaway coupler fitting. Soil or debris can interfere with the applicator flow metering system.
10. Insert the male coupler (hose end fitting) back into the female coupler of the breakaway coupler unit. Be sure the couplers are securely reattached, check the connection to be sure they are attached.
11. Close the applicator flow meter and all bleeder valves that were opened.
12. Open nurse tank liquid withdrawal valve and hose end valve when ready. If all connections are tight and do not leak, replace the gloves and goggles in the nurse tank emergency kit.

If the instructions for your particular breakaway valve differ from the instructions listed above, follow yours. However, never modify the written instructions on a piece of equipment by changing or eliminating steps.

Safety features on the applicator should be checked everytime before using the equipment in the field. See Table 7 for a checklist to prevent forgetting a safety check. Frequent safety checks are a must when working with anhydrous ammonia.

Table 7. Applicator Components

Always use a hitch pin with a safety clip to be sure the nurse tank will not detach from the applicator and that the applicator will not detach from the tractor. When moving this equipment on public roads be sure to also use the safety chains, they should be used in the field as well to prevent disconnects.

The applicator shut-off mechanism should work freely and reliably. It is important for efficient application and field safety.

Condition of the applicator knives is important for safety reasons as well as quality application. Knives in a poor or plugged condition will result in repeated stops for cleaning and unplugging, which raises the chance of an exposure to anhydrous ammonia. Plugged knives can trap pressurized ammonia that will be released when the knife is finally cleared.

Many exposures to anhydrous ammonia occur as a sagging low pressure discharge hose is inadvertently brushed against. The anhydrous ammonia in the sag will flow toward the applicator knife and be released. The amount of ammonia in the sagging tube can cause a serious injury. All low pressure tubes should be of the same length for a uniform delivery to the knives. The extra length can be coiled and securely fastened to the frame to reduce sagging. Kinks in the low pressure tubing can trap quantities of ammonia also, so avoid them.

The applicator flow meter and distribution system must work reliably and uniformly. With the applicator in the lowered position for applying, the manifolds should be mounted level, front to back and side to side, to provide a uniform flow to all knives or openers. Many accidents occur due to faulty equipment and impatient workers. When unplugging metering screens, close the liquid withdrawl valve on the nurse tank, the hose valve at the applicator, and open the bleeder valve on the applicator side of the nurse tank withdrawal valve. Then turn the applicator on and bleed it down. Leave the system open until the screen is cleaned and replaced into the meter.

Transport Safety Practices

The operator of a vehicle towing anhydrous ammonia equipment (applicator and nurse tanks) on the road is fully responsible for its safe transport. When nurse tanks are involved;

• A farmer, rancher, dealer, or commercial fertilizer company employee may pull not more than two portable tanks behind a farm tractor, pickup, or truck.
• The speed limit may not exceed 25 miles per hour, empty or full.
• The overall length of the entire transporting unit may not exceed 75 feet.
• Nurse tanks can be transported on public roads between sunrise and sunset only.
• A slow moving vehicle emblem must be displayed on the rear. A lighted rotating or flashing amber light may be displayed in lieu of the SMV emblem.
• Safety chains must be used if anhydrous nurse tanks are towed faster than 15 miles per hour.
• Tanks must be identified front and rear and both sides with the words "ANHYDROUS AMMONIA" in letters not less than 2 inches high.
• Tanks must be placarded front and rear and on both sides with approved DOT "NON-FLAMMABLE GAS" placards.
• The "1005" DOT decals are also required to be on the nurse tank.

Should a mishap occur while transporting anhydrous ammonia, the spill or leak should be approached from upwind whenever possible. To minimize the gas cloud, water should be sprayed on the point of discharge, not just on the tank. If emergency help is needed, call toll free 1-800-472-2121.

Safe Field Practices

• Always have an 8 ounce squirt bottle of water on your person and readily available when working with any anhydrous ammonia equipment.
• Always wear gloves and goggles when connecting or disconnecting nurse tanks and applicators or working on them.
• Always have a backup set of gloves, goggles, respirator with approved cartridge, and 5 gallons of fresh, clean, emergency water in the cab of the tractor applying the ammonia and the pickup transporting nurse tanks.
• Always hire or allow only persons 16 years of age or older to transport or apply anhydrous ammonia. The only exception is, youth may do this work on their parent's or legal guardian's farm, but not on public roadways, according to the terms of federal child labor law.
• Employ only trained workers to transport or apply anhydrous ammonia.
• Always work upwind of applicator knives, applicator flow meter, hose connections, bleeder valves, nurse tank valves, fixed liquid level gauges, and all other openings to the nurse tank or application equipment.
• Always point the hose end away from yourself and other people.
• Always carry the nurse tank hose by the valve body or coupling, never by the valve wheel or control handle.
• Always be sure hose/applicator connectors are clean before connecting them.
• Always hand tighten the valve wheel, never use a wrench to tighten it; that can easily damage the valve or seals.
• Always follow the recommended procedure for connecting and disconnecting nurse tanks and applicators. Avoid shortcuts.
• Always park nurse tanks, empty or full, downwind and away from populated areas such as houses and businesses. Transport nurse tanks out of town; do not park them in town or on city streets.
• Always let people know where you are working and what you are doing. If you're late they will know where to look for you.

Private Stationary Storage Facilities

Stationary storage facilities not used for retail sales or disbursement of anhydrous ammonia are required to have the same safety facilities as commercial stationary storage facilities. The requirements are based on the storage capacity of the facility, regardless whether retail sales are being conducted or not.

Required Safety Equipment

Loading platforms are required at bulk storage facilities since climbing or standing on the wheels of nurse tanks is not permitted while filling nurse tanks.

Personal Protective Equipment

The following five personal protective equipment items are required by the North Dakota Anhydrous Ammonia Law to be readily available at the storage site.

1. Two full face gas masks with spare ammonia canisters for each must be readily available at the site. The spare canisters must be date-current.
2. One pair of ammonia impervious, protective gloves. Two pair of such gloves are recommended, one pair for backup.
3. One pair of non-vented goggles that meet ANSI Z87.1 impact specifications. As with the gloves, it is recommended that two pair be available, one pair for backup.
4. One pair of protective boots that are impervious to ammonia. Two pair would be better.
5. One "slicker suit," a rain suit which is impervious to ammonia. A second suit is recommended in case a helper is needed in an emergency

A safety shower or an open water reservoir capable of holding at least 150 gallons of clean water is needed for complete body immersion. A stock water tank easily meets this requirement. The water must be kept clean.

A fire extinguisher is required along with a telephone or FM radio for communication.

Operators of an ammonia storage facility must be competent in safe operating procedures and must be able to handle emergency situations with appropriate action. They must be trained and the training documented by signed forms showing the type of training, the date of training, the persons trained and the person doing the training. These forms must be on record for at least three years and available for review during normal business hours.

Due to the large quantity of anhydrous ammonia in an ammonia transport semi-trailer, and its mobility, there is considerably more risk to the surrounding area if an uncontrolled release should occur than from a farm nurse tank. Because of this risk, agricultural producers can only transfer anhydrous ammonia from cargo tanks to their nurse tanks when specific safety requirements are met. These requirements are;

• The transport tank must have complete, up-to-date certification and labeling.
• Wheel chocks of adequate size must be used on the transport tank and the nurse tank before the transfer processes begin.
• The transport tank must have a 5-gallon reservoir of clean water, ammonia impervious gloves, a full face piece respirator with an ammonia canister along with a spare, and the non-vented goggles.
• The nurse tanks must be equipped with a 5-gallon reservoir of clean water, a legal decal illustrating the step-by-step ammonia transfer process, and a legal decal explaining first-aid procedures to follow when exposed to ammonia.
• The transfer process must be done on a firm, well prepared, level surface during daylight hours on the owner's or consignee's property;

• a facility must be built at least 50 feet from any adjoining property or any highway or railroad mainline
• at least 450 feet from any residence or public assembly
• at least 750 feet from any institutional residence
• at least one mile from any city limits.

• The board of county commissioners must be notified by an initial written notification from the owner or consignee of the intention to transfer anhydrous ammonia from any transport tank to nurse tanks in the particular county.
• The owner or consignee must also fully comply with all additional requirements imposed on the ammonia transfer operation by the county and/or township.

Summary

Anhydrous ammonia is a fertilizer commonly used in North Dakota agriculture. There is a high degree of risk in working with it due to its strong affinity for water, its caustic nature, high pressure and very low temperature created when pressure is released. The caustic nature of anhydrous ammonia is the cause of the severe chemical burning injury. The extremely low temperature is the cause of frostbite and frozen tissue resulting from exposure.

Flushing with water is the best and only first aid treatment for an exposure. Exposure to the eyes and respiratory system presents the greatest challenge in administering first aid. The victim should always be taken to professional medical help as soon as possible. Continue to flush the exposure while in transport.

There are many safety features which must be built into the anhydrous ammonia handling and application system. Some safety features have service life limitations supported by state laws because these features are not repairable in the field and require trained technicians to service them. The purpose for these service life limitations is to keep these parts in good working condition and to minimize the risk of failure.

Transferring anhydrous ammonia from one container to another or to an applicator involves risk. Transfer procedures (the opening and closing of valves, the connecting and disconnecting of hoses) must be done in a consistent manner from one tank to the next. The equipment for making these transfers is consistent from tank to tank and tank to applicator, the procedures must be also. Variation in these procedures can easily result in an uncontrolled release and most likely an exposure to the worker.

Storing anhydrous ammonia in large bulk containers on the farm presents hazards similar to such storage at commercial installations. The need for particular safety equipment and procedures is the same, regardless of the location of the facility. All bulk storage facilities have certain required safety equipment and procedure requirements, differing from portable storage equipment such as nurse tanks and applicator tanks because the quantity stored is so different.

References

Aherin, Robert and Lee Schultz, Using Anhydrous Ammonia Safely on the Farm, Educational Package AG-EP-2192, Agricultural Extension Service, University of Minnesota, 1984.

American National Standards Institute, Inc., Safety Requirements for the Storage and Handling of Anhydrous Ammonia, Publication K61.1-1981.

Anhydrous Ammonia Safety, Iowa Fertilizer and Chemical Association, 1990.

Doss, Howard J., Preventing Ammonia Burns and How to Treat Them, Michigan State University Extension, Michigan State University, 1998.

North Dakota Century Code, Article 7-12, Chapters 7-12-01 through 7-12-01-08, Anhydrous Ammonia Regulation.

North Dakota Century Code, Chapter 19-20.2, Sections 19-20.2-01 through 19-20.2-10, Anhydrous Ammonia Facilities.

The Fertilizer Institute, External Visual Inspection Guidelines for Anhydrous Ammonia Nurse Tanks and Applicator Tanks, 1982.

Grisso, Robert D., David Morgan and Rollin D. Schnieder, Using Agricultural Anhydrous Ammonia Safely, EC94-738-B, University of Nebraska Cooperative Extension, University of Nebraska, 1994.

Schutske, John M., Using Anhydrous Ammonia Safely on the Farm, Minnesota Extension Service, University of Minnesota, 1998.

Schwab, Charles V., Mark Hanna and Laura Miller, Play it Safe with Anhydrous Ammonia, University Extension, Iowa State University.

AE-1149, August 1998

NDSU Extension Service, North Dakota State University of Agriculture and Applied Science, and U.S. Department of Agriculture cooperating. Sharon D. Anderson, Director, Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. We offer our programs and facilities to all persons regardless of race, color, national origin, religion, sex, disability, age, Vietnam era veterans status, or sexual orientation; and are an equal opportunity employer.
This publication will be made available in alternative format upon request to people with disabilities (701) 231-7881.

North Dakota State University
NDSU Extension Service

[ 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 ]
[ Summary ] [ References ]

AE-1149, August 1998

NDSU Extension Service, North Dakota State University of Agriculture and Applied Science, and U.S. Department of Agriculture cooperating. Sharon D. Anderson, Director, Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. We offer our programs and facilities to all persons regardless of race, color, national origin, religion, sex, disability, age, Vietnam era veterans status, or sexual orientation; and are an equal opportunity employer.
This publication will be made available in alternative format upon request to people with disabilities (701) 231-7881.

North Dakota State University
NDSU Extension Service