Jumat, 13 Juli 2007

ANSI Color Codes

Why are the ANSI color codes important? What does the yellow background mean?

The yellow background signifies that the piping may handle hazardous material. Unfortunately, much has changed in the typical plant over the last 70 years since this standard was originally conceived. The basic standard can be traced to the 1920's and use in the US military. Obviously, our definitions for what is "hazardous" has changed. Water, air or carbon dioxide, under certain situations (pressure, heat, mixture with other chemicals) are not always benign. How do we interpret, for example, materials that should be used for "fire quenching" that are also "hazardous"? Should we use the red or the yellow ANSI scheme? Or, how do we label a pipe that carries both the liquid (which should be green) and gas form of a chemical (which should be blue)?

Hazards, in other words, are not so easily defined. "Hazardous" may mean that the material is hazardous to a person nearby, or to the operation of the overall plant itself. Could "hazardous" mean that the materials flowing through the process piping, if not handled carefully, could contaminate the product. Or, if leaked into the atmosphere, could the chemical infect the environment or cause damage to employees after cumulative exposure over a period of years? Clearly, the ANSI standard was written for far simpler times.

Color

Std

Meaning

Example

Red

APWA

Electric Power Lines, Cables, Conduit and Lighting Cables

Buried High Voltage Line

Yellow

APWA

Gas, Oil, Steam, Petroleum or Gaseous Materials

Natural Gas Distribution Line

Orange

APWA

Communication, Alarm or Signal Lines, Cables or Conduit

Buried Fiber Optic Cable

Blue

APWA

Water, Irrigation and Slurry Lines

Buried Water Line

Green

APWA

Sewers, Drain Line

Buried Storm Sewer Line

Red

Traffic

Prohibition

STOP, Yield

Orange

Traffic

Temporary Work Zone

Construction Zone Ahead

Yellow

Traffic

Caution

Merge Ahead, Slow

Blue

Traffic

Information Signs

Hospital

Brown

Traffic

Historical or Park

Picnic Area Ahead

Green

Traffic

Directional Signs

Exit 1 Mile, Go

Red

ANSI Sign

Danger Signs, Highest Hazard

Hazardous Voltage Will Cause Death

Orange

ANSI Sign

Warning Signs, Medium Hazard

Hazardous Voltage May Cause Death

Yellow

ANSI Sign

Caution Signs, Lowest Hazard

Turn Machine Off When Not In Use

Blue

ANSI Sign

Notice Signs

Employees Only

Green

ANSI Sign

Safety First Signs

Wear Ear Plugs

Red

ANSI Pipe

Fire Quenching Materials

Fire Protection Water

Yellow

ANSI Pipe

Materials Inherently Hazardous

Chlorine

Blue

ANSI Pipe

Materials of Inherently Low Hazard, Gas

Compressed Air

Green

ANSI Pipe

Materials of Inherently Low Hazard, Liquid

Storm Drain

Blue/Red/Yellow

NFPA 701

Blue is used for Health Hazards, Red for Flammability and Yellow for reactivity

NSI Color Code for Thermocouple and Thermocouple Extension Wire

ANSI
Symbol

Wire Alloys

Polarity

Thermocouple Wire Color

T/C Extension Wire Color

Individual

Jacket

Individual

Jacket

J

Iron
Constantan
(TM)

+JP
-JN

White
Red

Brown

White
Red

Black

K

CHROMEL®*
ALUMEL
®*

+KP
-KN

Yellow
Red

Brown

Yellow
Red

Yellow

T

Copper
Constantan
(TM)

+TP
-TN

Blue
Red

Brown

Blue
Red

Blue

E

CHROMEL®*
Constantan
(TM)

+EP
-EN

Purple
Red

Brown

Purple
Red

Purple

N

Nicrosil(TM)
Nisil
(TM)

+NP
-NN

Orange
Red

Brown

Orange
Red

Orange

RSX

Copper
Copper Alloy

+RSP
-RSN

-

-

Black
Red

Green

BX

PCLW630/Copper
Copper

+BP
-BN

-

-

Grey
Red

Grey

W3X
W5X

Alloy 203; Alloy 405
Alloy 225; Alloy 426

+WP
-WN

-

-

White/Red
Red

White/Red


* CHROMEL® and ALUMEL® are registered rademarks of Hoskins Manufacturing Company. PMC Corporation reserves the right to substitute equivalent product to CHROMEL® and ALUMEL® at any time.
For additional information see Bare Wire Data Sheet

Variations in color-coding standards are inevitable in our complex plant and pluralistic society. While laudable, harmonization of color-codes, then, will be very difficult to achieve. Many plants use other color-coding; for example, color-code each system (i.e. Lube Oil is brown, Condensate is green, etc.>) or color code by Unit (i.e. Unit 1 is yellow, Unit 2 is blue, etc.). For most plants, we recommend either the ANSI pipe marker color codes or simply black on yellow markers. For more complex plants, we recommend a color-coding by system. For all environments, we recommend the inclusion of RTK information on the valve or on the pipe.

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