While it may seem like pressure measurement is a very modern and highly technical and technology-based application, pressure has been measured for centuries with high degrees of accuracy using very basic types of equipment.
One of the first types of pressure manometer designs was the U-tube, which was invented by Dutch scientist and mathematician Christiaan Huygens in 1661. This was followed very shortly by the liquid column manometer invented by Italian physicist and mathematician, Evangelista Torricelli, which in fact is the model for the modern mercury barometer.
U-Tube Manometer Basics
The U-Tube manometer works on very simple principles as well. The liquid in the bottom of the U moves based on gravity and the liquid’s density compared to the pressure, providing consistent measurements without any need for continual calibration.
When equal pressure is applied to the open ends of the tubes the level of the liquid on either side of the tube will be the same. When different atmospheres are on either side of the tube the liquid height in each of the columns of the U-Tube will change. This change can be measured as the difference between the two.
A liquid can also be used to measure differential pressures. These pressure manometers can use water for small differences or mercury or other specific types of liquids for greater pressures. The specific gravity, the vapor pressure and the temperature range of each of these types of liquids have to be carefully considered when making a selection.
To eliminate the special requirements of the traditional U-Tube, or even the inclined-tube manometers, digital models are now available. These are very accurate and easily be quickly calibrated as needed.
Using microprocessors, this modern pressure manometer options are highly accurate and can read to a level not possible with other manometers. Also, since they don’t have the tubes and the liquid concerns, they are more effective across a greater range of environments.
The digital manometer can be completely portable or it can be permanently installed. In addition, the use of pressure measuring software can allow for corrections required in different types of applications, eliminating errors in reading and compensating for different factors.
While the old style of manually read manometers still have a place and are accurate to the degree needed in many applications, the digital manometer has the ability to take accuracy in pressure measurement to the next level.