ISO 7010 · W-series · Warning

W021 Warning; Flammable material

Our drawing, not ISO’s artwork.

Flammable material is stored or used here.

ISO 7010 reference: W021
Registered title: Warning; Flammable material ISO Online Browsing Platform, ISO 7010 - W021, Warning; Flammable material, reference number and registered title
Colour and shape: Yellow triangle with a black border, black symbol: Warning: a hazard is here

What the yellow triangle with a black border means

In HSE’s guidance on the UK Safety Signs and Signals Regulations 1996, a warning sign has a triangular shape Health and Safety Executive (HSE), L64 Safety signs and signals: The Health and Safety (Safety Signs and Signals) Regulations 1996. Guidance on Regulations (third edition), Part 2, warning signs, intrinsic features (a), page 14 and a black pictogram on a yellow background with black edging (the yellow part to take up at least 50% of the area of the sign) Health and Safety Executive (HSE), L64 Safety signs and signals: The Health and Safety (Safety Signs and Signals) Regulations 1996. Guidance on Regulations (third edition), Part 2, warning signs, intrinsic features (b), page 14

Its colour stands for: Warning sign, Be careful; take precautions; examine Health and Safety Executive (HSE), L64 Safety signs and signals: The Health and Safety (Safety Signs and Signals) Regulations 1996. Guidance on Regulations (third edition), Table 1, yellow or amber, meaning or purpose (page 12)

In the UK: HSE L64

Flammable material or high temperature Health and Safety Executive (HSE), L64 Safety signs and signals: The Health and Safety (Safety Signs and Signals) Regulations 1996. Guidance on Regulations (third edition), name under the warning signs in Schedule 1, page 15

In the US: OSHA

No OSHA general-industry rule we read names this sign or its subject. US signs follow OSHA 1910.145 and ANSI Z535; how the US sign classes work.

Signs people confuse with it, or find beside it

Other warning signs

Sources

ISO 7010 is a paid standard. Its OBP entries are free to view, but they are a script-driven app, so the title and reference number above are copied from the entry's own heading as it lists them (read 2026-09-29), not from the paid text. Other lines in quotation marks are HSE’s or OSHA’s words.

Health and Safety Executive (HSE): L64 Safety signs and signals: The Health and Safety (Safety Signs and Signals) Regulations 1996. Guidance on Regulations (third edition) (published 2015). Used here: name under the warning signs in Schedule 1, page 15; paragraph 63; Part 2, warning signs, intrinsic features (a), page 14; Part 2, warning signs, intrinsic features (b), page 14; Table 1, yellow or amber, instruction and information (page 12); Table 1, yellow or amber, meaning or purpose (page 12). www.hse.gov.uk Checked 2026-09-29.
ISO Online Browsing Platform: ISO 7010 - W021, Warning; Flammable material (registered safety sign entry). Used here: reference number and registered title. www.iso.org Checked 2026-09-29.