Hazardous Materials Autoignition Temperature - IP and IEC T-Code Classification

Sep 3, 2026

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Reference tables for hazardous materials provide autoignition temperatures in both Celsius and Fahrenheit, grouped by class and substance (e.g., acetylene, hydrogen, ammonia, hydrocarbons, and common fuels). The document also summarizes enclosure protection levels using an IP-style numerical scheme for solid-object and dust ingress protection, including liquid protection guidance via an IP second-number note. Additional classification maps NEC/CEC T-codes to IEC T-codes and lists maximum surface temperatures to support safe equipment selection and conformity checks in hazardous environments.

LanguageEnglish

CategoryGeneral

FormatPDF

Pages12

Reading Time4 min

AccessFree to download

Hazardous material autoignition temperatures

Classes and substances

Solid-object and dust protection levels (IP)

First number meaning

Liquid protection note (IP second number)

NEC/CEC to IEC T-code mapping

Maximum surface temperature limits

| Class | Group | Hazardous material | Autoignition temp. | | | --- | --- | --- | --- | --- | | | | | °C | °F | | I | A | Acetylene | 305 | 581 | | | B | Butadiene | 420 | 788 | | | | Ethylene Oxide | 570 | 1,058 | | | | Hydrogen | 500 | 932 | | | C | Acetaldehyde | 175 | 347 | | | | Cyclopropane | 498 | 928 | | | | Diethyl Ether | 180 | 356 | | | | Ethylene | 450 | 842 | | | | Isoprene | 398 | 743 | | | D | Acetone | 465 | 869 | | | | Ammonia | 651 | 1,204 | | | | Benzene | 498 | 928 | | | | Butane | 287 | 550 | | | | Ethane | 472 | 882 | | | | Ethanol | 363 | 685 | | | | Gasoline | 246-280 | 475-536 | | | | Methane | 537 | 999 | | | | Propane | 450 | 842 | | | | Styrene | 490 | 914 | | II | E | Aluminum | 650 | 1,202 | | | | Bronze | 370 | 698 | | | | Chromium | 580 | 1,078 | | | | Magnesium | 620 | 1,148 | | | | Titanium | 330 | 626 | | | | Zinc | 630 | 1,166 | | | F | Coal | 610 | 1,130 | | | G | Corn | 400 | 752 | | | | Nylon | 500 | 932 | | | | Polyethylene | 450 | 842 | | | | Sugar | 350 | 662 | | | | Wheat | 480 | 896 | | | | Wheat Flour | 380 | 716 | | 0 No special protection | | --- | | 1 Protected against solid objects over 50 mm, e.g. accidental touch by persons hands | | 2 Protected against solid objects over 12 mm, e.g. persons fingers | | 3 Protected against solid objects over 2.5 mm (tools and wires) | | 4 Protected against solid objects over 1 mm (tools, wires, and small wires) | | 5 Protected against dust limited ingress (no harmful deposit) | | 6 Totally protected against dust | | —
IP second number-Protection against liquids | | NEC/CEC designation T – code | IEC designation T-code | Max. surface temp. | | | --- | --- | --- | --- | | | | °C | °F | | T1 | T1 | 450 | 842 | | T2 | T2 | 300 | 572 | | T2A | | 280 | 536 | | T2B | | 260 | 500 | | T2C | - | 230 | 446 | | T2D | | 215 | 419 | | T3 | | 200 | 392 | | T3A | T3 | 180 | 356 | | T3B | | 165 | 329 | | T3C | - | 160 | 320 | | T4 | T4 | 135 | 275 | | T4A | - | 120 | 248 | | T5 | T5 | 100 | 212 | | T6 | T6 | 85 | 185 |

FAQs

How are hazardous materials organized in the autoignition temperature table?

They are grouped by class and sub-group, with each listed hazardous material showing autoignition temperature in °C and °F.

What does the IP first number indicate in the protection level section?

It indicates protection against solid objects of specified size ranges, including accidental touch by hands, fingers, tools/wires, and dust ingress limitations.

How do NEC/CEC T-codes relate to IEC T-codes and maximum surface temperatures?

The document provides a cross-reference table where each T-code (NEC/CEC) corresponds to an IEC designation and specifies the maximum surface temperature in °C and °F for that category.

Sep 3, 2026

Upload by Cipher