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November 2001 International Cranes 47

SAFE view

But lets get back to the core subject of this

article, namely how the imperial units compareto the SI units (Systme International dUnits).

When knowing the correct conversion factors,one can convert the non-SI units into SI unitsand vice versa. The American NIST (NationalInstitute of Standards and Technology) based inthe US is the only place on earth where one canfind the official values of all physical constants.Even the French BIPM (Bureau Internationaldes Poids et Mesures) refers to the published

values of the NIST. In the crane, rigging andtransport industry, the most commonly usedunits are for weight, volume, dimensionand pressure. So lets check out the conversion

In my previous article I explained the differ-

ence between mass (M) and force (F) and thereasons why we need to move heavy loadsslowly. The more abrupt a movement starts

or stops, the greater the acceleration/decelera-tion is, and consequently, the larger the force willbe. A very unfortunate example of this theory

was the collapse of the World Trade Center inNew York on 11 September. Due to the aircraftcrashing into the building around the 90th floor,a fire started. The intensity of the heat caused thesteel structure to weaken until it eventually gave

way. More then 20 stories of structure above this

section of weakened steelsuddenly dropped a cou-ple of metres and wasabruptly stopped by therest of the structureunderneath. This enor-mous deceleration andthe resultant force (F =mass x acceleration)caused the structureunderneath it to collapse

with disastrous effect. Allengineering designsapply so-called dynamic

factors, which is a safety margin to account forsudden shock loads.However, these dynamic factors do not accountfor the enormous forces caused by the impact of an aircraft or a 20-storey section of a building.

&In the concluding half of atwo-part feature, Richard

Krabbendam continues hisanalysis of universal physical

constants and therelationships between them.

He also lays out a series ofhandy conversion charts.

continued

WEIGHTSOunce (troy) = 31.1034768 g *Pound = 453.59237 g *Stone = 14 pound = 6.35029318 kg *Ton long (UK) = 1016.0469088 kg *Ton short (US) = 907.18474 kg *Tonne (US, metric ton) = 1000 kg

VARIOUS UNITSCFM (cubic feet per minute) =28.316847 litre/minKnot UK = 0.5147733 m/sKnot international = 0.514444 m/s =

1 nautical mile/hr = 1.852 km/hrMesh = 1 inch 1ppm (part per million) = 1 mg/kgppb (part per billion) UK = 1 _g/m 3ppb (part per billion) US = 1 mg/m 3

US LIQUIDSGallon (gal) = 4 quart = 8 pint = 32 gill = 231 in 3*(cubic inch)Quart (qt) = 2 pint = 57.75 in 3*Pint (pt) = 4 gill = 28.875 in 3*Gill (gi) = 7+ 7/32 (= 7.21875) in 3*

AREA Are (a) = 100 m 2Centiare (ca) = 1 m 2Hectare (ha) = 10000 m 2Bunder = 1 ha (agriculture)

Acre = 4046.8564224 m 2 *Square foot = 0.0929 m 2

Units,massforces

Knowing the conversion factors, one can easily convert Imperial values into the SI units and vice- versa. One particular use is determining outrigger set-up.

VOLUMESBarrel US petroleum =158.987294928 dm 3*(159 litre)Bushel (UK) = 36.36872 dm 3*Bushel (US) = 35.23907016688 dm 3*Gallon UK = 4.54609 dm 3*(4.55 litre)Gallon US liquid = 3.785411784 dm 3*(3.78 litre)Ounce UK fluid = 28.4130625 cm 3*Ounce US fluid = 29.5735345625 cm 3 *Pint UK = 568.26125 cm 3*(0.568 litre)Pint US liquid = 473.176473 cm 3 *(0.473 litre)Quart UK = 1.1365225 dm 3

*(1.136 litre)Quart US dry = 1.101220942715 dm 3*Quart US liquid = 0.946352946 dm 3*Register ton = 2.8316847 m 3

(* = exact value)

LENGTHInch = 2.54 cm = 25.4 mm *Foot = 0.3048 m =12 inch = 30.48 cm =304.8 mm *

Yard (yd) = 3 feet = 36 inch = 91.44 cm *Fathom = 1.8288 m *Mile Statute = 1609.344 m *.

This is the mileMile Nautical international (sea mile) =1852 m *

The present international sea mileMile Nautical, sea mile = 1828.8 m *

A frequently used sea mile of 6000 feetMil = 1/1000 inch = 0.0254 mm *

CONVERSION CHARTS

In the crane and rigging industry, the most commonly used units are for weight, volume,dimension and pressure.

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