What is Anhydrous Ammonia

Ammonia Nh3 OSHA Description

NM    :  Ammonia
REV   :  19930115
SYN   :  Anhydrous ammonia
IMIS  :  0170
CAS   :  7664-41-7
NIOSH :  RTECS BO0875000
DOT   :  1005 15
DESC  :  Colorless gas with a penetrating, pungent, suffocating odor. 
         It can be a liquid when under pressure.  Mixtures of 
         air-ammonia may explode.  UEL=25 
         MW: 17    BP: -28 F    VP: >1 atm    MP: -108 F 
OSHA  :  50 ppm, 35 mg/m3
TLV   :  25 ppm, 17 mg/m3 TWA; 35 ppm, 24 mg/m3 STEL
REL   :  25 ppm TWA; 35 ppm STEL
SYMPT :  Eye, nose, throat irritation; dyspnea, bronco spasms; chest pain;
         pulmonary edema; pink frothy sputum; skin burns; vesiculation
HLTH  :  Respiratory Effects---Acute lung damage/edema (HE11) 
         Irritation-Eye, Nose, Throat, Bronchi, Skin---Marked (HE14) 
ORG   :  Respiratory system, eyes
SLC1  :  MEDIA: Sulfuric Acid impregnated Carbon Bead (Supelco ORB0-77 tube
         .      or equivalent)
         MAX V: 24.0 Liters    MAX F: 0.1 L/min (TWA)
         MAX V:  7.5 Liters    MAX F: 0.5 L/min (STEL)
         ANL 1: Ion Chromatography; IC/Conductivity
         . REF: 2 (OSHA ID-188)    SAE: 0.25    CLASS: Fully Validated
SAM2  :  DEVICE: Detector Tube     COMPANY: Kitagawa 
         PART #: 105SC             RANGE: 12.5 - 125 ppm    CLASS: 3rd Party 
         


         DEVICE: Instrumentation   COMPANY: HNU 
         PART #: Photoionization Detector                     CLASS: Mfg 
WIPE  :  No
SS    :  218300

COMMENT:

You will hear a lot of people saying anhydrous ammonia is a very dangerous refrigerant. Most of them being Freon Technicians, why? because when people do not understand something or have not been educated or trained in a field or chemical they tend to use their gut feelings. Yes ammonia smells bad and yes if released in large quantities can kill you, but if handled properly can be used safely and without danger to anyone. Yes (ammonia) has it's place and is not recommended for use in large public areas unless located (engine room and storage) away from the central areas. A secondary refrigerant should be used, such as a brine or glycol mixture. A 300 ton system does have it's place but the above listed area is not one of them. The best way to make ammonia safe to use starts with safety engineering. A properly engineered system can be as safe as any refrigeration system, taking into consideration the dangers associated with this refrigerant compared to others. In many cases freon is a better choice because large populated areas are not as easy to control should a leak or release occur. Anhydrous Ammonia as a refrigerant offers many benefits to it's users and can and has become a safer choice simply because of better training made available to technicians, owners, plant operators and others associated with this chemical.

P.S.
One of ARTA'S many goals is to assist anyone and everyone interested in the proper use of this refrigerant, safety being the most important factor in our efforts. Please join us by becoming an active member today! Our goals require a team effort and we need your support Now to achieve them! 



THE FOLLOWING SOURCES OF INFORMATION ON ANHYDROUS AMMONIA ARE RECOMMENDED:
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  Pamphlet C-2, Anhydrous Ammonia
  Compressed Gas Association
  Phone (703) 412-0900
  1235 Jefferson Davis Highway
  Arlington, VA 22202

  Pamphlet ANSI K61.1
  Safety Requirements for the Storage & Handling of Anhydrous Ammonia;
  American National Standards Institute
  1430 Broadway
  New York, NY 10018

  Storage and Handling of Anhydrous Ammonia
  29 CFR 1910.11
  Code of Federal Regulations, Title 29-Labor

  Ammonia Data Book
  International Institute 13 Ammonia Refrigeration
  Phone (202) 857-1110
  1101 Connecticut Ave. NW, Suite 700
  Washington, DC 20036


ANHYDROUS AMMONIA PROPERTIES
Anhydrous ammonia is the compound formed by the combination of the two gaseous elements, nitrogen and hydrogen, in the proportion of one part nitrogen and three parts of hydrogen by Volume. Since one volume of nitrogen weighs fourteen times as much as one volume of hydrogen, on a weight basis, the ratio is fourteen parts of nitrogen to three parts of hydrogen, or about 82% nitrogen and 18% hydrogen. At atmospheric temperatures and pressures, anhydrous ammonia is pungent colorless gas. Anhydrous Ammonia boils at -28 F and freezes to a white crystalline mass at -107.9NF. When heated above its critical temperature of 270.3NF ammonia exists only as a vapor regardless of the pressure. Between the melting and critical points, liquid ammonia exerts a vapor pressure which increases with rising temperature. When liquid ammonia is in a closed container it is in equilibrium with ammonia vapor and the pressure within the container bears a definite relationship to the temperature. Ammonia liquid is lighter than water, having a density of 42.57 pounds per cubic foot at -28 F., while as a vapor, ammonia is lighter than air, its relative density being 0.5970 compared to air at atmospheric pressure and temperature of 32NF. Under the latter conditions, one pound of ammonia vapor occupies a volume of 22.5 cubic feet and yields 45 cubic feet of dissociated gas at a ration of 25% nitrogen and 75% hydrogen. Because of its great affinity for water, care must be taken in the storage and handling of ammonia to keep it dry. "Anhydrous" means "without water". When ammonia gas is dissolved in water, the resulting material is called ammonium hydroxide or "Aqua" ammonia. The two materials, anhydrous ammonia and aqua ammonia should not be confused.

PHYSICAL CONSTANTS OF ANHYDROUS AMMONIA
 --------------------------------------- 


Molecular symbol ------------------------------------- NH3
Molecular weight ------------------------------------- 17.032
Boiling point at one atmosphere ---------------------- -28 F.
Freezing point at one atmosphere --------------------- -107.9 F.
Critical temperature --------------------------------- 270.32 F.
Critical pressure ------------------------------------ 1657 psia.
Vapor density at -28 F. and one atmosphere ----------- 0.05555 lb./cu.ft.
Heat of combustion ----------------------------------- 8001 Btu/lb.

This Information offered by: ARTA as reference materials only! All information certified: UL Document Verification Revision 1995 File T7 NC2068 revised: 5/1996


HAZARD SUMMARY "Nh3"


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