Flow restrictor

Any component — a gicleur (jet), orifice, or restricting valve — that narrows the path between the pump and the group. Used to control how aggressively water reaches the puck during pre-infusion and the early part of the shot.

Why it matters — Flow restrictors are the hidden variable behind why two machines with identical pumps and identical pressure gauges can produce completely different shots. A smaller restrictor means gentler ramping; a bigger one means a more immediate shot.

Good to know

• On E61 machines, the gicleur is the most common flow restrictor — typical sizes are 0.6–0.9 mm.
• Reducing gicleur size smooths the shot for light roasts and reduces channelling; increasing it produces faster, sharper extractions.