Thursday, August 21, 2014

Why is mercury used in measuring blood pressure?

Mercury has been used, for quite some time, in blood pressure measurement. The device used for this application is also known as sphygmomanometer. The pressure measurement is based on the rise of measuring fluid in a vertical column. The ideal fluid for such an application is something that should be stable at room temperature and rises to a manageable height (so as to have a compact device). Mercury is an ideal choice for this application. Mercury has a specific gravity of 13.6. That is, its density is 13.6 times that of water. Thus, it only rises to a certain height and keeps the equipment portable (imagine the height of the vertical column if water was used instead of mercury). Thus, mercury is commonly used in blood pressure monitors and a number of other pressure measurement devices.


Nowadays, alternate devices that do not use mercury are also available. An example is the battery powered digital blood monitor that can be easily used at home.


Hope this helps.  

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