severe bronchial irritation. If your skin is exposed to a corrosive, flush the exposed area with water for at least fifteen minutes. Then seek medical treatment. Strong acids All concentrated acids can damage the skin and eyes, and their burns are very painful. Nitric, chromic, and hydrofluoric acids are especially damaging because of the types of burns they inflict. Seek immediate medical treatment if you have been contaminated with these materials (particularly hydrofluoric acid). Strong alkalis The common strong bases used in the labs include potassium hydroxide, sodium hydroxide, and ammonia. Burns from these materials are often less painful than acids. However, damage may be more severe than acid burns because the injured person, feeling little pain, often does not take immediate action and the material is allowed to penetrate into the tissue. Ammonia is a severe bronchial irritant and should always be used in a well-ventilated area, if possible in a hood. Dehydrating agents This group of chemicals includes concentrated sulfuric acid, sodium hydroxide, phosphorus pentoxide, and calcium oxide. These chemicals have a powerful affinity for water. When skin is exposed to these chemicals, serious burns may result. A large amount of heat is produced when mixing these substances with water; mixing should always be done by adding the agent to water, and not the reverse. Oxidizing agents In addition to their corrosive properties, powerful oxidizing agents such as Perchloric and Chromic Acids (sometimes used as cleaning solutions) present fire and explosion hazards on contact with organic compounds and other oxidizable substances. The hazards associated with the use of Perchloric acid are especially severe. It should be handled only after thorough familiarization with recommended operating procedures. Special Handling Procedures Corrosive chemicals should be used in the chemical fume hood, or over plastic trays when handled in bulk quantities (> 1 liter) and when dispensing. When working with corrosives, wear gloves, goggles, long sleeved lab coat and
Table 1: Maximum allowable quantities for flammable and combustible liquids (Source: NFPA Code, §30) Table 2: Separation of Gas Containers, Cylinders, and Tanks by Hazard Class (Source: NFPA Code, §55) Gas Category Other Gas Unstable Reactive, 2, 3, or 4 Toxic or Highly Toxic or Highly toxic — 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) — Pyrophoric — 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) — 6.1 m (20 ft) Flammable — 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) — 6.1 m (20 ft) 6.1 m (20 ft) Oxidizing — 6.1 m (20 ft) 6.1 m (20 ft) — 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) Corrosive — 6.1 m (20 ft) — 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) Unstable Reactive, Class 2, 3, or 4 — — 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) Other Gas — 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft) 6.1 m (20 ft)
this Chart: To determine if two gases must be segregated, locate one gas category in the far left and then the second gas type in the top row. Table 3: Maximum Allowable Quantity of Gases per Laboratory (Source: NFPA Code, §55) Unsprinklered Sprinklered Areas Materials No gas cabinet, gas room, or exhausted enclosure Gas cabinet, gas room, or exhausted enclosure No gas cabinet, gas room, or exhausted enclosure Gas cabinet, gas room, or exhausted enclosure Corrosive Gas Liquefied Nonliquefied 68 kg (150 lb) 23 m3 (810 ft3) 136 kg (300 lb) 46 m3 (1620 ft3) 136 kg (300 lb) 46 m3 (1620 ft3) 272 kg (600 lb) 92 m3 (3240 ft3) Cryogenic Fluid Liquefied Nonliquefied 0 L (0 gal) 170 L (45 gal) 170 L (45 gal) 340 L (90 gal) 170 L (45 gal) 340 L (90 gal) 170 L (45 gal) 681 L (180 gal) Flammable Gas Liquefied Nonliquefied 114 L (30 gal) 28 m3 (1000 ft3) 227 L (150 gal) 28 m3 (2000 ft3) 227 L (60 gal) 28 m3 (2000 ft3) 454 L (120 gal) 56 m3 (4000 ft3) Highly Toxic Gas Liquefied Nonliquefied 0 kg (0 lb) 0 m3 (0 ft3) 2.3 kg (5 lb) 0.6 m3 (20 ft3) 0 kg (0 lb) 0 m3 (0 ft3) 4.5 kg (10 lb) 1.1 m3 (40 ft3) Nonflammable Gas Liquefied Nonliquefied No Limit No Limit No Limit No Limit No Limit No Limit No Limit No Limit Oxidizing Gas
Liquefied Nonliquefied 57 kg (15 gal) 43 m3 (1500 ft3) 114 kg (30 gal) 85 m3 (3000 ft3) 114 kg (30 gal) 85 m3 (3000 ft3) 227 L (60 gal) 170 m3 (6000 ft3) Pyrophoric Gas Liquefied Nonliquefied 0 kg (0 lb) 0 m3 (0 ft3) 0 kg (0 lb) 0 m3 (0 ft3) 1.8 kg (4 lb) 1.4 m3 (50 ft3) 3.6 kg (8 lb) 2.8 m3 (100 ft3) Toxic Gas Liquefied Nonliquefied 68 kg (150 lb) 23 m3 (810 ft3) 136 kg (300 lb) 46 m3 (1620 ft3) 136 kg (300 lb) 46 m3 (1620 ft3) 272 kg (600 lb) 92 m3 (3240 ft3)
Asphyxiation As the liquid gas warms and becomes airborne, oxygen may be displaced to the point that employees and lab personnel may experience oxygen deficiency or asphyxiation. Any area where such materials are used should be well ventilated. For this same reason, employees and lab personnel should avoid lowering their heads into a dry ice chest. (Carbon dioxide is heavier than air, and suffocation can result.)