What is the ‘bar’ pressure of a commercial espresso machine and what range of bar pressures does a commercial espresso machine operate

What is the ‘bar’ pressure of a commercial espresso machine and what range of bar pressures does a commercial espresso machine operate at? What is optimum ‘bar’ pressure for perfect espresso coffee?

You can check the answer of the people under the question at Quora “15 or 20 bar coffee machine

0 thoughts on “What is the ‘bar’ pressure of a commercial espresso machine and what range of bar pressures does a commercial espresso machine operate”

  1. A proper espresso grind has bi-modal particle size distribution (large particles known as boulders and small particles as fines).
    If pressure is too high, fines migrate to the bottom of the puck and seal the basket filter holes. Coffee ceases to pour.
    If pressure is too low, water flows slowly.
    Hence, at a specific pressure, typically between 8-9 bar, flow rate is maximized and pour comes out faster. This is the optimum pressure for extraction.
    Now – if it is too fast, grind finer (both particles are now smaller) and you’ll increase the % of solids in the coffee, and get a more syrupy espresso.
    Pressure gauges on espresso machines are both inaccurate as well as typically connected to the boiler, before any gicleurs (tiny orifice flow rate limiters that help keep the fines from migrating by making the pressure on the puck rise slower than the pump would allow). Because of this, they do not show the true extraction pressure on the puck.
    For example, on my LM espresso machine (which has a single commercial group) – the gauge shows about 10bar while a Scace like device (which measure pressure on the puck for an adjustable flow rate) shows about 8.5 bar at optimum flow rates.

    Reply
  2. Our machine is best at just over 1 but that I think equals 10 bars.. and it makes the most lovely crema… however in a semi automatic that isn’t the only variable… grind, weather and having a PID control or not… we have a rocket Cellini

    Reply
  3. ‘Bar’ is a measure of pressure and equates to 1 atmosphere. The word ‘bar’ comes from the Greek “baros” meaning weighty. It is the same root word that is used in “barometer” which is an instrument that measures atmospheric pressure.
    Pressure is a measure of force against a surface and is usually expressed as a ‘force per unit area’. Normal atmospheric pressure equates to the weight of a column of air one square inch in area rising from the Earth’s surface, through the atmosphere and into space. The weight (or pressure) of this column of air on the earth’s surface is measured at 14.7 pounds. i.e 14.7 pounds per square inch (psi). So, 14.7psi = 1atm (atmosphere) = 1bar of pressure.
    Bar pressure is usually identified on the gauges displayed on the front panel of commercial espresso coffee machines (see image below). One gauge displays the pressure in the boiler (usually set at 1bar) and the other displays the pressure of the hot water being produced by the pump as it extracts the coffee essence from the finely ground roasted coffee beans in the detachable portafilter. This gauge will usually rest at about 2-3bar which is typically the water pressure found in most municipal mains water supplies. This measure raises and maintains a reading of about 8-10bars during the process of extracting the espresso coffee essence.

    What is the 'bar' pressure of a commercial espresso machine and what range of bar pressures does a commercial espresso machine operate

    There are two types of pumps used to create the water pressure necessary for espresso coffee essence extraction:
    * Rotary Pump: This pump type is used in all commercial espresso machines and in some high-end home espresso ones as well. Rotary pumps need to be plumbed into the mains water supply. This pump type is necessary for making a large number of coffees or when making more than one cup at a time. Taking water from the mains supply, these pumps create enough pressure in the machine piping circuit to allow the water to pass through the finely ground coffee to perfectly extract the espresso coffee essence. These pumps use rapidly oscillating vanes inside a sealed pump that push water through the espresso machine at high pressures. A by-pass connection allows the pump to keep water pressure in the system at the pre-set level. While the pump pressure can reach as high as 15bar, it is usually set at between 8 and 10bars for optimum espresso coffee extraction. These pumps are sometimes referred to as a volumetric pumps, or by a trade name, Procon.
    * Pulsing pumps: These are much smaller and considerably cheaper pumps than the rotary…

    Reply

Leave a Comment