The Pressure for Great Coffee

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 Pressure for Great Coffee

If you are a coffee connoisseur, getting the right brew is essential. Besides fresh ground beans of a specific type, for many people an essential element in the brewing process is pressure.

In fact, by definition, espresso is brewed by passing high pressure water through the coffee. According to guidelines from the Istituto Nazionale Espresso Italiano, the entry water pressure is 9 ± 1 bar (130.5 ± 14.5 psi) , the entry water temperature is 88 ± 2°C and the coffee is brewed for 25 ± 2.5 s.

With these specific criteria, it is not surprising that coffee making machines were developed to ensure that the precise process is followed consistently. A commonly used coffee machine for commercial applications can easily cost thousands of dollars and it is not unusual for the machine to have a pressure indicating gage on it.

LaCimbali Coffee Machine

This LaCimbali coffee machine indicates 2 bar (29 psi), the incoming line pressure, with a maximum possible reading of 10 bar (145 psi).

Another brewing technique involving pressure is the Moka pot. This stove top or electric device uses steam pressure to push water through coffee grinds. Unlike an espresso machine, the pressure in a Moka pot is only about 1 bar (14.5 psi) and is assured by steam pressure, so no measurement would be involved.

The Keurig coffee machine automates a pressurized hot water process and precise quantity of coffee in pods to deliver a consistent brew to the user. The pressure is fixed and lower than an espresso machine but the user can select the amount of water to satisfy their taste buds. These machines are typically priced under $100 so there is no pressure indication to the consumer. However, the nozzle/needle can become clogged and then the machine shuts down and displays a ‘Water Under Pressure’ warning. Also, to ensure proper functioning at higher altitudes of 5,000 feet and above, some Keurig machines have a user selectable high altitude mode.

Do you have a pressure sensing question? Let us know and we’ll address it in an upcoming blog.
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