The Ups and Downs of Pressure

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities, and you.

The Ups and Downs of Pressure

Higher and lower pressures can occur in what seem like unusual circumstances.  In plumbing, for example, much higher pressures occur if air gets into a water line and the faucet is closed quickly. Called water hammer, the effect causes audible noise or the banging of pipes. The hydraulic shock wave can, in some cases, cause severe damage since the pressure is so high. Draining the system is the usual solution to this problem.

On the down side, many people are surprised when they open a refrigerator door, close it and then try to immediately reopen it. The negative pressure in the refrigerator caused by this activity can be so extensive in well-sealed systems that it takes significant forced to re-open the door. The decreased pressure results from cooling of the warmer air entering the refrigerator. Based on ideal gas law, the pressure decrease could be 10% or more. In deep freezer units and those with the best sealing, the effect is even stronger producing even lower pressures.

Ideal gas law: P V = n R T

Where: P is the pressure, V is the volume occupied by n moles of any gas at temperature (T) in Kelvin and R is the gas constant.

Central Restaurant Products Walk-In Freezer

Walk In Freezer courtesy of Central Restaurant Products.

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