- Posted by Stephen Whiteley
- On 17/06/2008
- English, Fire protection, Numbers, Technical translations
The other day we had to translate this sentence from a fire protection specification:
Standard weight (150 lb (68 kg)) minimum) fittings shall be used.
It seems straightforward enough, but it’s got a number of traps. 150 pounds is indeed 68 kilograms and the reference to “weight” seems unambiguous. And yet it’s all wrong. The 150 lb actually refers to the pressure rating of the fittings and is short for pounds per square inch, or psi. The higher the pressure the fittings are designed to withstand, the heavier they are likely to be. 150 psi fittings (often referred to as 150 # fittings, when # is a US symbol for pounds averdupois, are are a typical, ordinary sort of fitting, which is why they are referred to here as “standard weight”. The adjective “standard” has nothing to do with the noun “standard”, which would mean a formal technical standard (French norme, German Norm, etc.) and is usually best translated as “normal”.
Back to the pressure rating. (Oops, “rating” reminds one of “rate”, which is another dreadful false friend. I’ve seen “pressure rating” translated into Spanish as “tasa de presión”, which would be the rate at which pressure is used or applied, and nothing to do with “presión nominal”, the nominal pressure, which is the correct translation for “pressure rating”. And I often see “flow rate” translated as “tasa de flujo”, a horrible expression, when any decent engineer knows is “caudal” (a measure of the amount of flow, like French débit or German Durchfluss or throughflow.)
The pressure rating is 150 psi, which is 10.35 bar in SI units. So should we translate as 150 psi (10.35 bar) fittings? Perhaps… But probably not. The writer probably has one of two idea in mind:
- Use fittings manufactured to American standards and rated at 150 psi, in which case we should not convert it at all, but just leave it as 150 psi.
- Use fittings rated at 150 psi or their local or metric equivalent. The metric equivalent is 10 bar. This is one of the standard rated pressures The next one up happens to be 16 bar.
So should the translation should be fittings with a normal rating of 150 psi (10 bar) will be used? We’re still not quite there, since metric standards refer in fact to PN10 as a pressure rating (from the French pression nominale).
One more small issue: “shall” is not an ordinary English future tense here. When used in engineering standards, rules and specification, it means “must”.
And there we have it:
The fittings to be used shall have a minimum pressure rating of 150 psi (PN10).
This simple sentence is a minefield which requires quite sophisticated engineering and technical knowledge before a single word can be translated into another language.