Pièze (pz)

French (Ancien Régime)Historical unit (no longer in standard use)

Exactly 1,000 pascals (1 kPa): the pressure unit of the old French meter-tonne-second (MTS) system.

1 pièze = 1,000 pascals (exactly).

About the pièze

French metrologists coined the pièze, symbol pz, for pressure in the metre-tonne-second (MTS) system, which was France's legal system from 1919 to 1961. The Soviet Union adopted the same system in 1933 and abolished it in 1955. The name is French, and Wikipedia does not explain its origin further.

The MTS system used large units suited to industry rather than laboratories, and the pièze follows that pattern. It is defined as one sthène of force per square metre, which works out to exactly 1,000 pascals, or one kilopascal. That is the same as 10 millibars or one centibar, about 7.5 torr, and roughly 0.145 pounds per square inch.

Compared with everyday pressures, one pièze is about one hundredth of standard atmospheric pressure, so steam boilers and hydraulic machinery of the period would be quoted in tens or hundreds of pièzes. The unit disappeared with the MTS system, and the kilopascal now fills the same role.

Sources: Wikipedia: Pièze; Wikipedia: Metre-tonne-second system of units

Pièze conversion chart

1 pièze expressed in every other pressure unit:

More French (Ancien Régime) units

• ligne (length)
• pouce (length)
• pied du roi (length)
• toise (length)
• lieue (Paris league) (length)
• arpent (North American) (area)
• degree Réaumur (temperature)
• degree Delisle (temperature)
• poncelet (power)
• sthène (force)

All French (Ancien Régime) units

Browse all pressure units.