Units and conversion factors

I was brought up on mmHg (millimetres of mercury) as units of gas pressure (tension).
Some will find it necessary to convert these units into SI units (Système International).

Where possible "conversion" beans allow you to choose your favourite units.
Internally the program runs on mmHg.  If you have any favourite units that are not included please email me.

The conversion beans are demonstrated below.  Two beans are connected and you can choose different units in the drop-down boxes to the right of the data entry field.  (Note the data entry field goes red during data entry and black when a value is confirmed.)

You can check the conversion factors at these sites.

How Many?A Dictionary of Units of Measurement

A Dictionary of Units

Gas pressures

Torr is a non-metric unit of pressure equal to exactly 1/760 atmosphere, about 1.333 22 millibars, or 133.322 Pascals.
The pressure of 1 atmosphere is almost exactly equivalent to the pressure of a column of mercury 760 millimetres high. 
As a result, 1 torr is the same thing as 1 mmHg within 1 part per million.
The unit is named for Evangelista Torricelli (1608-1647), the Italian scientist who invented the barometer.

1 mm of water exerts a pressure of 9.80665 Pascals, 1cm H2O 98.0665 Pascals
1 mm Hg = 133.322 Pascals = 1.3595 cm H2O

Hydrogen ion concentration

Converting between units for hydrogen ion concentration is a tad more tricky.
The beans below demonstrate this conversion.