Rocket Espresso Expansion Valve R999904983 – RE & Boxer Pressure Relief

Dial-in flavour and guard your hydraulic system with this factory expansion valve, part R999904983. Threaded into the pump line on Boxer and RE machines, the precision spring-and-seat assembly vents excess brew pressure back to the reservoir, keeping your gauge rock-steady around 9 bar while sparing pumps and seals from strain. Low-lead brass construction resists corrosion, and the external hex head lets you fine-tune pressure in seconds—perfect for single-origin profiling or compensating for filter-basket changes.

Key Features & Benefits

• Adjustable relief range – fine-tune brew pressure for optimal flavour
• Low-lead brass body – food-safe, descaling-friendly and long-lasting
• Precision spring & PTFE seat – holds set-point accurately; eliminates pressure spikes
• External hex adjuster – tweak with a wrench; no disassembly needed
• Quick swap-in – standard Rocket threads; install in minutes

Compatibility

• Boxer 2014, Boxer (202009-), Boxer (202405-)
• RE A 2014 / 2016
• RE-A (201912-) / (202207-)
• RE-S (201802-)
• RE-Timer (201806- / 202207-)

Refresh your pressure control with this genuine Rocket Espresso valve and enjoy consistent crema, quieter operation and longer component life.