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Silica, amorphous

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Synonyms & Trade Names
Diatomaceous earth, Diatomaceous silica, Diatomite, Precipitated amorphous silica, Silica gel, Silicon dioxide (amorphous)
CAS No.
7631-86-9
RTECS No.
VV7310000
DOT ID & Guide
Formula
SiO₂
Conversion
IDLH
3000 mg/m3
See: 7631869
Exposure Limits
NIOSH REL
TWA 6 mg/m3
OSHA PEL
TWA 20 mppcf (80 mg/m3/%SiO2) See Appendix C (Mineral Dusts) See Appendix G
Measurement Methods
NIOSH 7501
See: NMAM or OSHA Methods
Physical Description
Transparent to gray, odorless powder. [Note: Amorphous silica is the non-crystalline form of SiO2.]
Molecular Weight
60.1
Boiling Point
4046°F
Melting Point
3110°F
Solubility
Insoluble
Vapor Pressure
0 mmHg (approx)
Ionization Potential
NA
Specific Gravity
2.20
Flash Point
NA
Upper Explosive Limit
NA
Lower Explosive Limit
NA
Noncombustible Solid
Incompatibilities & Reactivities
Fluorine, oxygen difluoride, chlorine trifluoride
Exposure Routes
inhalation, skin and/or eye contact
Symptoms
irritation eyes, pneumoconiosis
Target Organs
Eyes, respiratory system
Personal Protection/Sanitation
(See protection codes)
Skin:No recommendation
Eyes:No recommendation
Wash skin:No recommendation
Remove:No recommendation
Change:No recommendation
First Aid
(See procedures)
Eye:Irrigate immediately

Breathing:Fresh air
Respirator Recommendations

NIOSH

Up to 30 mg/m3:
(APF = 5) Any quarter-mask respirator.
Click here for information on selection of N, R, or P filters.

Up to 60 mg/m3:
(APF = 10) Any particulate respirator equipped with an N95, R95, or P95 filter (including N95, R95, and P95 filtering facepieces) except quarter-mask respirators. The following filters may also be used: N99, R99, P99, N100, R100, P100.
Click here for information on selection of N, R, or P filters.
(APF = 10) Any supplied-air respirator

Up to 150 mg/m3:
(APF = 25) Any supplied-air respirator operated in a continuous-flow mode
(APF = 25) Any powered, air-purifying respirator with a high-efficiency particulate filter.

Up to 300 mg/m3:


(APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter.
Click here for information on selection of N, R, or P filters. 


(APF = 50) Any supplied-air respirator that has a tight-fitting facepiece and is operated in a continuous-flow mode
(APF = 50) Any powered, air-purifying respirator with a tight-fitting facepiece and a high-efficiency particulate filter
(APF = 50) Any self-contained breathing apparatus with a full facepiece
(APF = 50) Any supplied-air respirator with a full facepiece

Up to 3000 mg/m3:
(APF = 1000) Any supplied-air respirator operated in a pressure-demand or other positive-pressure mode

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 with an N100, R100, or P100 filter.
Click here for information on selection of N, R, or P filters. 


Any appropriate escape-type, self-contained breathing apparatus

Important additional information about respirator selection

See also
INTRODUCTION
Page last reviewed: October 30, 2019
Content source: National Institute for Occupational Safety and Health