Chemical Tankers / Day 2 / Day 2 Topic 1 USCG Chemical Guide

1.6 Fire and Explosion Hazard Data

Fire & Explosion Data

1.6 Fire and Explosion Hazard Data

o Grade explanation

The classification assigned by the Coast Guard to flammable or combustible liquids is defined as follows:

Grade A - Flammable liquid with a Reid vapor pressure of 14 psi and more;

Grade B – Flammable liquid with a Reid vapor pressure of more than 8,5 psi but less than 14 psi;

1.6 Fire and Explosion Hazard Data

o Grade explanation (contd.)

Grade C - Flammable liquid with a Reid vapor pressure of 8.5 psi or less and flash point of 80F or below;

Grade D - Combustible liquid with a flash point above 80F but below 150F;

Grade E - Combustible liquid with a flash point of 150F or above;

1.6 Fire and Explosion Hazard Data

o Electrical Group

The electrical group is based on the explosive characteristics of air mixtures of gases or vapors. Various US publications provide a details and list the chemicals by Group incl. “Classification of Gases, Liquids and Volatile Solids Relative to Explosion”

1.6 Fire and Explosion Hazard Data

o Flash Point

The lowest temperature at which the vapors of a liquid may be ignited momentarily.

Values given in the data sheets are open cup except where “(cc)” designated. In general the open cup value is about 10-15F higher.

1.6 Fire and Explosion Hazard Data

o Flammable Limits

The minimum and maximum concentrations of vapor in air which will burn or explode if an ignition source is present.

Commonly called LEL and UEL.

Below the LEL the mixture is too lean to burn, and above the UEL it is too rich to burn

1.6 Fire and Explosion Hazard Data

o Auto ignition Temperature

The minimum temperature required to ignite gas or vapor without the spark or flame being present.

1.6 Fire and Explosion Hazard Data

o Extinguishing Media

A list of firefighting materials suitable for use on the burning materials:

Water Fog - a finely divided mist produced by either a high or low velocity fog nozzle;

Water foam - either mechanical or chemical, produced by a special foam nozzle or by fixed system;

1.6 Fire and Explosion Hazard Data

o Extinguishing Media cont.

Alcohol Foam - this material blankets the fire in the same manner as conventional foam, but is intended for use with liquids which are soluble in water, such as alcohol & acetone;

1.6 Fire and Explosion Hazard Data

o Extinguishing Media cont.

CO2 - Carbon dioxide gas stored in a cylinders;

Dry Chemicals – Sodium or potassium bicarbonate or monosodium phosphate powder, usually available from a semifixed or portable extinguishers;