It's surprising that there are so many units of measure. It's actually surprising there are not more problems than there are.
Here at Homershams we have to deal with thread sizes and types; e.g. 1/4" BSP, 1/2" BSP Parallel and NPT. In temperature probes sometimes we're asked for 6mm and sometime 1/4" and they're not quite the same (6.35mm). Not to mention 2" gauges that are actually 63mm.
If only there was a 'lingua franca' we could all use. No wonder calibration is such a needed thing. Last week we had a gauge that was accurate on it's psi range but not when switched to kPa
If you find it difficult too, don't worry, you're in good company!
In 1999 NASA, with the budget of the GDP of a small country, managed to smash a probe into the surface of Mars at several hundred km/h because some engineers had used Metric and others Imperial units! A few years earlier, a Canadian 767 loaded with passengers, ran out of fuel at 40,000 ft because the Captain entered his fuel load in kg and the refuellers used pounds. A patient, who should have been given 0.5 grains (0.065 grams) of barbituate, was given 0.5 grams! These are not new problems. Christopher Columbus, aiming for Asia, landed in the Bahamas instead because he was using Roman miles, rather than Nautical! In case you're interested, a Roman mile is 1478-metres, a nautical mile 1852m and a land-mile 1609m Another problem unit of measure is the gallon; A US gallon being 3.785 litres and an Imperial gallon, 4.546 litres. |
The International System of Units (S.I.) is the modern form of the metric system. It is the only system of measurement with an official status in nearly every country in the world
The most common prefixes are:-
centi = one hundredth (1/100)
milli = one thousandth (1/1000)
kilo = one thousand
mega = one million
Its all about putting the em-phar-sis on the right syl-ar-bel!
Mostly we get the pronunciation correct –
mega-watt of electricity, kilo-gram for mass; milli-meters or centi-meters for length but insist on calling 1000m a kilom-eter, not kilo-meter!