The coffee is then brought through the coffee grounds. This design of espresso maker eliminates the need for manual labor. This is the least favorable method because it produces temperatures to hot for espresso brewing, resulting in a bitter tasting drink. The pump driven system is better because it exerts the desired, no more than nine bars of pressure to produce a quality drink , while other methods produce more. Now before I go any further, you the reader must be confused as to what is a bar.
Pressure produced by any bar has a value.
This value is called a bar and is equal to .99 atmospheres. One atmosphere is equal to 14.72 lbs. Per square inches and is the pressure exerted by the earth s atmosphere. When you are standing at sea level the pressure of the earth s atmosphere is exerting 15 lbs per square inches against your body.