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B21. Pressure pump
This element is responsible for taking water from the cold water tank and transferring it to the boiler.
The cold water drives the water inside the boiler towards the soluble product EVs or to the espresso
coffee brewing
group
.
E1. Bypass
E2. Anti-return
When espresso coffee needs to be prepared, it offers a high resistance to the flow of water, since the
coffee is ground and pressed down by the piston of the brewing
group
. This resistance of the coffee
increases the pressure at which the pump supplies the water to the boiler; as the water pressure
increases, the water coming out of the boiler to brew coffee can reach pressures of up to 9 kg/cm². The
pump bypass (2) is opened at this pressure, allowing a small amount of water to be driven back, which is
enough to prevent the pressure at which the pump operates to exceed 9 kg/cm².
The bypass is a water outlet hole that is closed by a spring-driven ball. This spring can withstand a pressure
of 9 kg/cm², pressure at which it is compressed and allows water to flow through.
This pressure of 9 kg/cm² is the perfect pressure to prepare espresso coffee.
When a soluble product needs to be prepared, the water does not find resistance to reach the beater
from the boiler, so the pump works at a smaller pressure than when preparing espresso coffee when
preparing these products. The pump also features an anti-return valve that prevents water from being
driven back from the boiler.
