Decimal Equivalents of Fractions of an Inch

Fraction (Inch)	Decimal	Fraction (Inch)	Decimal	Fraction (Inch)	Decimal
1/64	0.015625	11⁄32	0.34375	43⁄64	0.671875
1/32	0.03125	23⁄64	0.359375	11⁄16	0.6875
3/64	0.046875	3⁄8	0.375	45⁄64	0.703125
1/16	0.0625	25⁄64	0.390625	23⁄32	0.71875
5/64	0.078125	13⁄32	0.40625	47⁄64	0.734375
3/32	0.09375	27⁄64	0.421875	3⁄4	0.750
7/64	0.109375	7⁄16	0.4375	49⁄64	0.765625
1/8	0.125	29⁄64	0.453125	25⁄32	0.78125
9/64	0.140625	15⁄32	0.46875	51⁄64	0.796875
5/32	0.15625	31⁄64	0.484375	13⁄16	0.8125
11/64	0.171875	1⁄2	0.500	53⁄64	0.828125
3/16	0.1875	33⁄64	0.515625	27⁄32	0.84375
13/64	0.203125	17⁄32	0.53125	55⁄64	0.859375
7/32	0.21875	35⁄64	0.546875	7⁄8	0.875
15/64	0.234375	9⁄16	0.5625	57⁄64	0.890625
1/4	0.250	37⁄64	0.578125	29⁄32	0.90625
17/64	0.265625	19⁄32	0.59375	59⁄64	0.921 875
9/32	0.28125	39⁄64	0.609375	15⁄16	0.9375
19/64	0.296875	5⁄8	0.625	61⁄64	0.953125
5/16	0.3125	41⁄64	0.640625	31⁄32	0.96875
21/64	0.328125	21⁄32	0.65625	63⁄64	0.984375

Calculated Industries 4020 Measure Master Pro Measurement Conversion Calculator

Weight and Measures

Measures of Length

1 mile = 1760 yards = 5280 feet

1 yard = 3 feet = 36 inches 1 foot = 12 inches

1 mil=0.001 inch

1 fathom = 2 yards = 6 feet 1 rod = 5.5 yards = 16.5 feet.

1 hand = 4 inches 1 span = 9 inches

1 micro-inch = one millionth inch or 0.000001 inch (1 micrometer or micron one millionth meter = 0.00003937 inch.)

Surveyor's Measure

1 mile = 8 furlongs = 80 chains

1 furlong = 10 chains = 220 yards

1 chain=4 rods = 22 yards = 66 feet = 100 links

1 link = 7.92 inches

Nautical Measure

1 league = 3 nautical miles

1 nautical mile = 6076.11549 feet = 1.1508 statute miles

1 knot = nautical unit of speed = 1 nautical mile per hour

One degree at the equator = 60 nautical miles = 69.047 statute miles 360 degrees = 21,600 nautical miles = 24,856.8 statute miles = circumference at equator

Square Measure

1 square mile = 640 acres = 6400 square chains

1 acre = 10 square chains = 4840 square yards = 43,560 square feet. An acre is equal to a square, the side of which is 208.7 feet.

1 square chain = 16 square rods = 484 square yards = 4356 square feet.

1 square rod = 30.25 square yards = 272.25 square feet = 625 square links

1 square yard = 9 square feet

1 square foot = 144 square inches

Measure used for Diameters and Areas of Electric Wires

1 circular inch = area of circle 1 inch in diameter = 0.7854 square inch

1 circular inch = 1,000,000 circular mils

1 square inch = 1.2732 circular inch = 1,273,239 circular mils

1 circular mil = the area of a circle 0.001 inch in diameter

Cubic Measure

1 cubic yard = 27 cubic feet

1 cubic foot = 1728 cubic inches

The following measures are also used for wood and masonry:

1 cord of wood = 4 × 4 × 8 feet = 128 cubic feet

1 perch of masonry = 16-1⁄2 × 1-1⁄2 × 1 foot = 24-3⁄4 cubic feet

Shipping Measure

For measuring entire internal capacity of a vessel:

1 register ton = 100 cubic feet

For measurement of cargo:

Approximately 40 cubic feet of merchandise is considered a shipping ton, unless that bulk would weigh more than 2000 pounds, in which case the freight charge may be based upon weight

40 cubic feet = 32.143 U.S. bushels = 31.16 Imperial bushels

Dry Measure

1 bushel = 1.2445 cubic feet = 2150.42 cubic inches

(U.S. or Winchester struck bushel)

1 bushel = 4 pecks = 32 quarts = 64 pints

1 peck = 8 quarts = 16 pints

1 quart=2 pints

1 heaped bushel = 11⁄4 struck bushel

1 cubic foot = 0.8036 struck bushel

1 British Imperial bushel = 8 Imperial gallons = 1.2837 cubic feet = 2218.19 cubic inches

Liquid Measure

1 U.S. gallon = 0.1337 cubic foot = 231 cubic inches = 4 quarts = 8 pints

1 quart=2 pints = 8 gills 1 pint=4 gills

1 British Imperial gallon = 1.2009

1 U.S. gallon = 277.42 cubic inches 1 cubic foot =7.48 U.S. gallons

Old Liquid Measure

1 barrel = 311⁄2 gallons 1 hogshead = 2 barrels = 63 gallons

1 pipe or butt = 2 hogsheads = 4 barrels = 126 gallons

1 tierce = 42 gallons 1 puncheon = 2 tierces = 84 gallons

1 tun=2 pipes = 3 puncheons

Apothecaries' Fluid Measure

1 U.S. fluid ounce = 8 drachms = 1.805 cubic inch = 1⁄128 U.S. gallon

1 fluid drachm = 60 minims

1 British fluid ounce = 1.732 cubic inch

Avoirdupois or Commercial Weight

1 gross or long ton = 2240 pounds 1 net or short ton = 2000 pounds

1 pound = 16 ounces = 7000 grains

1 ounce = 16 drachms = 437.5 grains

The following measures for weight are now seldom used in the United States:1 hundredweight = 4 quarters = 112 pounds (1 gross or long ton = 20 hundred-weights); 1 quarter = 28 pounds; 1 stone = 14 pounds; 1 quintal = 100 pounds

Troy Weight, used for Weighing Gold and Silver

1 pound = 12 ounces = 5760 grains

1 ounce = 20 pennyweights = 480 grains

1 pennyweight = 24 grains

1 carat =3.086 grains (used in weighing diamonds)

1 grain Troy = 1 grain avoirdupois = 1 grain apothecaries' weight

Apothecaries' Weight

1 pound = 12 ounces = 5760 grains

1 ounce = 8 drachms = 480 grains

1 drachm = 3 scruples = 60 grains

1 scruple =20 grains

Measures of Pressure

1 pound per square inch = 144 pounds per square foot = 0.068 atmosphere = 2.042 inches of mercury at 62° F. = 27.7 inches of water at 62°F = 2.31 feet of water at 62° F

1 atmosphere = 30 inches of mercury at 62° F. = 14.7 pounds per square inch = 2116.3 pounds per square foot = 33.95 feet of water at 62° F

1 foot of water at 62° F =62.355 pounds per square foot = 0.433 pound per square inch

1 inch of mercury at 62° F =1.132 foot of water = 13.58 inches of water = 0.491 pound per square inch

Miscellaneous

1 great gross = 12 gross = 144 dozen

1 quire=24 sheets

1 gross=12 dozen = 144 units

1 ream = 20 quires = 480 sheets

1 dozen=12 units

1 ream printing paper = 500 sheets

1 score=20 units

MABIS Tape Measure, Blue

Hazardous Area

Hazardous areas are classified into zones according to the nature of the gases present in the potentially explosive atmosphere, and the likelihood of that atmosphere being present. The nature of the atmosphere is characterized by the chemical composition of the gas and its ignition temperature, and the notions of gas grouping and temperature classification have been developed in order to formalize this.

A useful concept in the consideration of how explosions occur is the hazard triangle. The sides of the triangle represent fuel, oxygen and a source of ignition, all of which are required in order to create an explosion. For the purposes of this chapter, a fuel is considered as a flammable gas, vapor or liquid, although dust may also be a potential fuel. Oxygen is of course present in air at a concentration of about 21 per cent. The ignition source could be a spark or a high temperature. Given that a hazardous area may contain fuel and oxygen, the basis for preventing explosion is to ensure that any ignition source is either eliminated or prevented from coming into contact with the fuel-oxygen mixture.

Zone classification

The zone classification defined in IEC 79 is used in Europe and most other parts of the world; it is summarized in Table 16.1. Various types of explosion protection are available, and their suitability for the different zones is shown in the table.

Zone	Suitable protection
Zone 0 Areas in which hazardous explosive gas atmospheres are present constantly or for long periods, for example in pipes or containers	Ex ‘ia’ Ex ‘s’ (where specially certified Zone 0)
Zone 1 Areas in which hazardous explosive gas atmospheres are occasionally present, for example in areas close to pipes or draining stations	Ex ‘d‘; Ex ‘ib’; Ex ‘p’; Ex ‘e’; Ex ‘s’; Ex ‘o’; Ex ‘q’; Ex ‘m’; Equipment suitable for Zone 0
Zone 2 Areas in which hazardous explosive gas atmospheres are rare or only exist for a short time, for example areas close to Zones 0 and 1	Ex ‘N’/Ex ‘n’; Equipment suitable for Zones 1 & 0

In the USA hazardous areas are classified in a slightly different way, according to the National Electrical Code. In brief, hazardous areas are classified either as Division 1, where ignitable concentrations of flammable gases or vapors may be present during normal operation, or as Division 2, where flammable gases or vapors occur in ignitable concentrations only in the event of an accident or a failure of a ventilation system.

Gas grouping and temperature classification

The energy required for ignition differs from gas to gas, and the grouping of gases together with their classification by temperature is used in Europe to describe the suitability of a piece of electrical equipment for use with explosive atmospheres of particular gases.

Table below lists common industrial gases within their appropriate groups. Gas group I is reserved for the classification of equipment suitable for use in coal mines. Gas group I1 contains those gases found in other industrial applications, and it is subdivided according to the relative flammability of the most explosive mixture of the gas with air.

Group	Representative gases
I	Methane
IIA	Acetone, ethane, ethyl acetate, ammonia, benzol, acetic acid, carbon monoxide, methanol, propane, toluene, ethyl alcohol, I-amyl acetate, N-hexane, N-butane, N-butyl alcohol, petrol, diesel, aviation fuel, heating oils, acetaldehyde, ethyle ether
IIB	Town gas, ethylene (ethene)
IIC	Hydrogen, acetylene (ethyne), hydrogen disulphide

Temperatures are classified from T1 to T6, as shown in Table below 3. The levels show the maximum surface temperature permitted for equipment which has been assigned that temperature class, and the common gases for which each class is appropriate are also shown.

North American practice is to define hazardous materials in classes. Flammable gases and vapors are Class 1 materials, combustible dusts are Class 2 materials and ‘flyings’, such as sawdust, are Class 3 materials. Class 1 is subdivided into four groups depending on their flammability: A (including acetylene), B (including hydrogen), C (including ethylene) and D (including propane and methane). The subgroup letters are in the opposite order of flammability to the IEC groupings shown in Table 2. The North American temperature classification is similar to the IEC system shown in Table 3, but the classes are further subdivided to give more specific temperature data.

Class	Highest permissible surface temperature (oC)	Representative gases
T1	450	Acetone, ethane, ethyle acetate, ammonia, benzol, acetic acid, carbon monoxide, methanol, propane, toulene, town gas, hydrogen
T2	300	Ethyl alcohol, (-amyl acetate, N hexane, N-butane, N-butyl alcohol, ethylene
T3	200	Petrol, diesel, aviation fuel, heating oils
T4	135	Acetaldehyde, ethyl ether
T5	100
T6	85	Hydrogen disulphide

Refferrence

Newnes Electrical Engineer’s Handbook; D.F. Warne; 2000

Introduction to Health and Safety at Work, Fourth Edition