Caution Sign for Hazards


Laboratories, shops and maker spaces where hazardous materials are used or stored are required to post an up-to-date sign at the entrance. The sign is intended to alert emergency responders and visitors of potential hazards and precautions for entry.

EH&S installs the sign holder and posts the initial sign. Occupants update signs as needed using the tool available on the MyChem menu.

Create a sign

You must have an account in the MyChem chemical inventory system to create or edit a sign based on the chemical inventory in your laboratory, shop or maker space.

After logging into MyChem, click on the Caution Sign menu item and select the building and room (or suite) to create a customized sign for your location.

Understanding the NFPA Hazard Diamond

The National Fire Association (NFPA) has developed a color-coded number system called NFPA 704. The system uses a color-coded diamond with four quadrants in which numbers are used to signal the degree of health hazard (blue), flammability hazard (red), and instability hazard (yellow).

NFPA 704 example

Flammability, Health, and Instability

Brief descriptions of the rating numbers for the flammability, health, and instability sections are given in the table below. Numbers in these sections can range from zero to four, with zero meaning essentially no hazard and four indicating an extreme hazard.

These numbers will appear on your caution sign if your inventory contains amounts in the quantities that require a fire permit. You may have chemicals in your lab, shop or maker space, but show zeros on your NFPA diamond if the quantities do not meet or exceed the permit quantities.

Specific Hazards

The bottom diamond segment is white and it shows specific hazard codes that identify special problems or require special fire-fighting techniques. These specific hazards include OX (oxidizers), COR (corrosive materials) and W (use no water to fight fires).

The numeric ratings on the colored sections of the diamond on your caution sign are based on the hazard category and the quantity of material as recorded in your MyChem inventory.

For more information refer to the Table of NFPA codes and Permit Quantities.

explanation of hazard categories

Services Available

If you have questions about creating a caution sign, please read the FAQ section below or contact EH&S.

Frequently Asked Questions (FAQ)

The International Fire Code and some other regulations stipulate posting of warning signs under certain conditions. For detailed information, see the links listed under regulation and policy section of this page.

  • Emergency responders (police, fire, medical, spill response)

  • Visitors (vendors, contractors, students, and colleagues from other institutions)

  • UW authorized personnel such as EH&S staff, facilities services and custodial staff

  • General public who may pass by lab/shop

Any UW laboratory, shop or maker space where hazardous materials are used and/or stored is required to have a caution sign.

Labs, shops and maker spaces that have only computers or mechanical equipment (and no chemicals) would not need a caution sign. In this case, you may choose to have a caution sign to indicate that no chemical hazards are present and to display contact information and the “No Food or Drink” image.


The fire diamond provides a quick reference for emergency responders about materials in a room that may present health, flammability, instability, or special hazards under conditions of fire, spill, or similar emergencies.

You may not have enough flammable liquids to warrant the flammability rating. You need to have five gallons total (threshold quantity requiring a Seattle Fire Department permit) of certain classes of flammable liquids to require a number in the red diamond on your sign. See the Table of NFPA Codes and Permit Quantities  for the threshold quantities for each hazard category.

Alternatively, your MyChem inventory may be inaccurate. MyChem performs calculations using your MyChem inventory to determine the numeric hazard ratings for the diamond, so if your inventory is inaccurate, your sign will be inaccurate.

If you have an account in MyChem, the UW online chemical inventory system, you can make a sign for any of the rooms for which you have authorization. Click on ”Caution Sign” under the reports menu to begin creating your sign.

If you need a caution sign holder, contact EH&S at

Contact EH&S at or 206.616.4046.

One name is required for the sign although it will accommodate up to four contacts. After-hours phone numbers are strongly recommended but not required. A department contact such as an administrator is recommended for general information. Lab, shop or maker space contacts are recommended for emergencies and entry after normal business hours. A home phone number, cell phone number or 9-1-1 may be typed in "After Hours Phone" column. Home phone numbers can be added or modifed under the menu item My Contacts.

EH&S installs acrylic holders, usually near the room number plaque. If no holder is outside your door, please contact EH&S at 206.616.5530.

The principal investigator, safety coordinator or their authorized designee.

Generally "authorized personnel" means:

  • Anyone assigned to work in the space

  • Anyone who has been specifically authorized to enter the space

  • UW personnel who, as a part of their responsibility, provide services to spaces such as Facilities Services staff, custodians, EH&S staff and UW Police

  • Labs and shops may restrict entry to protect staff or protect their research and require entry by permission only

The principal investigator, safety coordinator or their authorized designee.

While we can’t name all the regulatory required signs that are not covered by this sign, there are a few common ones that were purposely omitted primarily because they are too complex or variable and require separate signs.

Examples include:

  • Laser warnings
  • UV light hazards
  • Strong magnets
  • Radiation signs for X-ray and high radiation hazards
  • Biosafety Level 2 and 3 signs restricting access while work is in progress
  • Microwave radiation signs

The biohazard symbol on the caution sign indicates that the lab, shop or maker space is authorized at the BSL-1, BSL-2, or BSL-3 level.

If biohazardous materials are present and being manipulated in the lab, shop or maker space, additional sign with more information is required to be posted on the door. For more information, please visit the Biological Research Safety page.

If you have any compressed gas cylinders in your lab, shop or maker space (and it is listed in your MyChem inventory) the compressed gas symbol will appear on your sign. However, compressed gases will only be listed under the NFPA fire diamond if they meet the permit threshold quantities. See the Table of NFPA Codes and Permit Quantities for more information.

Check to make sure the gases are entered in your MyChem inventory. Your compressed gases need to be entered in MyChem in order for the symbol to appear on your sign.

The best way to remove a sign from the holder is to stick the sticky side of a piece of 'post-it' note paper between the plexiglass and the paper sign, so the sticky part is touching the paper sign. Push on the outside of the plexiglass to stick the post-it to the paper sign and slowly pull on the post-it. The sign should slide right out.

More Information


MyChem Contact

(206) 616-4046
Reference Files