How to Read HAZCHEM Code?

Till sometime back firemen had no way of knowing what medium of extinguishing unknown chemicals in a fire, spillage, or any emergency should be used. Incorrect actions resulted in disasters.

Availability of information on the hazardous nature of the substance and required control measures help the emergency management personnel to take quick and correct decisions.

The HAZCHEM code (also called Emergency Action Code) gives vital information to the fire brigade and other emergency services on the action to be taken to combat spillage, leakage, or fire in an emergency involving a hazardous substance.

The HAZCHEM code consists of a number from 1 to 4 and any one of the letters, P, R, S, T, W, X, Y, Z followed at times by the letter E.

The numbers signify the extinguishing medium to be employed as given in table 3 on the left.

The letters signify 4 aspects viz.

1. Method of controlling spillage a) by diluting or b) by containing
2. Personal protective equipment to be worn by firefighters
3. Reactive nature of Chemical, and
4. Need for evacuation.

The fire services personnel should carry the HAZCHEM code, scale, and notes for guidance as given in Table 4.

Table 4

HAZCHEM Code of some important and popular chemicals transported on Indian roads are given in table 5:

Table 5

It is important to note here that the objective of the HAZCHEM code is not to identify the chemical carried in the vehicle. The purpose of the HAZCHEM code is only to provide guidance on the basic approach to dealing with an emergency.

In interpreting the HAZCHEM code, the following points will be useful:

• If necessary, a fire fighting medium represented by a higher number than that shown may be used, but not represented by a lower number.
• Where the letter appears as white on black, police and other non-fire service personnel need to wear breathing apparatus only for fire and not for spillage, but firemen are required to wear it in both cases.
• Letter E indicates that the officer in charge should consider civil evacuation of the area

The Indian Chemical Manufacturers Association (ICMA), in their publication "Code for Safe Transportation of Hazardous Substances by Road," recommends that at least the area within a radius of 300m should be considered for evacuation wherever 'E' appears in the HAZCHEM code.

For example for ethylene oxide with UN number 1040 and HAZCHEM code is 2PE and would be decoded as:

• 2- Fog equipment is recommended (through extinguishing agents corresponding to a higher number may also be used).
• P- Can be violently (V) reactive. Full body clothing with breathing apparatus is necessary. The substance may be diluted and washed to drain.
• E- Consider evacuation as the first priority.

For motor spirit with UN number 1203, the HAZCHEM code is 3YE, and this would mean:

• 3- Use Foam only.
• Y- Can be violently (V) reactive or explosive. Breathing apparatus plus protective gloves to be used in case of fire. Personal protective equipment is not a requirement in case of spillage. Any spillage of the substance should be contained.
• E- Consider evacuation as a first priority.