what do the numbers "on the square plates of trucks" that are hauling
hazardous,liquid, or any kind of substance mean? I would like to find
a page that details and show the substance number meaning.

Hello jc120380-ga,

Thank you for your question.


The square plates on trucks that you’re referring to are called
placards. The numbers are the identification numbers of the hazardous
substance according to The Hazardous Material Table.

The links below explain more about placards.

“All hazardous and radioactive material shipments use marking,
labeling, and placarding to communicate the level of hazard associated
with a shipment’s contents to handlers, transporters, first
responders,and the public. Placarding is required for certain types
and amounts of hazardous material and is placed on a vehicle to alert
the public and first responders as to the hazards located in the
vehicle.”
U.S. Department of Energy
http://www.nv.doe.gov/programs/envmgmt/blackmtn/WMTransportation.htm

“Hazardous materials pose a risk to health, safety, and property
during transportation. The Hazardous Materials Table lists these
materials. The rules sometimes require diamond shaped warning signs on
vehicles with hazardous materials. These signs are called placards.”
Highway Safety and Motor Vehicles Website
http://www.hsmv.state.fl.us/handbooks/Commercial/3section_207.html

Placards are put on the outside of a vehicle to show the hazard class
of the cargo. This excerpt describes where the placards must be
placed.
 
“A placarded vehicle must have at least 4 identical placards. They are
put on the front, rear, and both sides. Placards must be readable from
all four directions. They are 10 3/4 inches square, turned upright on
a point, in a diamond shape. Cargo tanks show the I.D. number of their
contents on placards or orange panels.”
Highway Safety and Motor Vehicles Website (Figure 7-2)
http://www.hsmv.state.fl.us/handbooks/Commercial/3section_207.html

The identification number of the hazardous material must appear on the
placard. The Hazardous Materials Table shows material's shipping name,
hazard class or division, identification number, packaging group, and
required labels.

The Hazardous Material Table can be found here:
http://63.141.231.101/cgi-bin/om_isapi.dll?advquery=%5bGroup%20hm215d-header%5d%20Or%5bGroup%20hm%20215d%5d&infobase=netdot&record=dochitfirst&recordswithhits=on&softpage=Document42

You can read more on this subject in the Hazardous Material
Transportation Guide.
National Transportation Library
http://ntl.bts.gov/DOCS/hmtg.html

Search Criteria:

://www.google.com/search?sourceid=navclient&hl=es&q=hazardous+material+table+%2Dpdf

://www.google.com/search?sourceid=navclient&hl=es&q=specifications+for+vehicle+placarding+for+hazardous+waste+%2Dpdf

://www.google.com/search?sourceid=navclient&hl=es&q=designation+of+cargo+for+transport+of+hazardous+materials

://www.google.com/search?sourceid=navclient&hl=es&q=hauling+hazardous+waste+vehicle+placards


I hope this provides you with the information you are seeking.

Best regards,

Bobbie7-ga

If you wish to go a step beyond the helpful answer provided above, you
may wish to download (1.7 megabytes, PDF) or purchase (@$19.00 U.S.)
the Emergency Response Guidebook, which details the chemicals
associated with the various placards used on trucks as well as how
emergency personnel should respond to accidents. It is, to say the
least, eye opening.

Download:
http://hazmat.dot.gov/gydebook.htm

Purchase (Emergency Response Guidebook, 2000):
http://bookstore.gpo.gov/sb/sb-040.html