NIOSH Publication No. 2005-151:

NIOSH Pocket Guide to Chemical Hazards

September 2005

Nitric acid

CAS
7697-37-2

HNO3

RTECS
QU5775000
Synonyms & Trade Names

Aqua fortis, Engravers acid, Hydrogen nitrate, Red fuming nitric acid (RFNA), White fuming nitric acid (WFNA)
DOT ID & Guide
2031 / 157 (other than red fuming)
2032 / 157 (fuming)

Exposure
Limits

NIOSH REL: TWA 2 ppm (5 mg/m3) ST 4 ppm (10 mg/m3)
OSHA PEL: TWA 2 ppm (5 mg/m3)
IDLH
25 ppm See: 7697372
Conversion
1 ppm = 2.58 mg/m3
Physical Description
Colorless, yellow, or red, fuming liquid with an acrid, suffocating odor. [Note: Often used in an aqueous solution. Fuming nitric acid is concentrated nitric acid that contains dissolved nitrogen dioxide.]
MW: 63.0
BP: 181°F
FRZ: -44°F
Sol: Miscible
VP: 48 mmHg
IP: 11.95 eV

Sp.Gr(77°F): 1.50
Fl.P: NA
UEL: NA
LEL: NA

Noncombustible Liquid, but increases the flammability of combustible materials.
Incompatibilities & Reactivities

Combustible materials, metallic powders, hydrogen sulfide, carbides, alcohols [Note: Reacts with water to produce heat. Corrosive to metals.]
Measurement Methods
NIOSH 7903; OSHA ID165SG
See: NMAM or OSHA Methods
Personal Protection & Sanitation
(See protection)
Skin: Prevent skin contact
Eyes: Prevent eye contact
Wash skin: When contaminated
Remove: When wet or contaminated
Change: No recommendation
Provide: Eyewash (pH<2.5), Quick drench (pH<2.5)
First Aid
(See procedures)
Eye: Irrigate immediately
Skin: Water flush immediately
Breathing: Respiratory support
Swallow: Medical attention immediately
Respirator Recommendations
NIOSH/OSHA
Up to 25 ppm:
(APF = 25) Any supplied-air respirator operated in a continuous-flow mode*
(APF = 50) Any chemical cartridge respirator with a full facepiece and cartridge(s) providing protection against the compound of concern
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern
(APF = 50) Any self-contained breathing apparatus with a full facepiece
(APF = 50) Any supplied-air respirator with a full facepiece
Emergency or planned entry into unknown concentrations or IDLH conditions:
(APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode
(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus
Escape:
(APF = 50) Any air-purifying, full-facepiece respirator (gas mask) with a chin-style, front- or back-mounted canister providing protection against the compound of concern/Any appropriate escape-type, self-contained breathing apparatus
Important additional information about respirator selection
Exposure Routes
inhalation, ingestion, skin and/or eye contact
Symptoms
Irritation eyes, skin, mucous membrane; delayed pulmonary edema, pneumonitis, bronchitis; dental erosion
Target Organs
Eyes, skin, respiratory system, teeth
See also: INTRODUCTION   See ICSC CARD: 0183   See MEDICAL TESTS: 0158