Silicone rubber extruded tubes are indispensable key components in coffee machines, running through almost the entire workflow from water intake to beverage output (such as steaming milk for frothing). They are primarily used to transport water and steam and to connect various internal functional modules.
Below are their specific applications, key performance requirements, and general specifications in coffee machines. Main Application Scenarios
Water Inlet/Outlet and Tubing Connections: Connect the water tank, water pump, and heating element. They transport room-temperature water to the heating system and then direct hot water to the brewing assembly for extraction.
High-Temperature Steam Delivery: Used to connect the boiler to the steam wand. Thanks to their excellent heat resistance, they safely deliver high-temperature steam for milk frothing, maintaining good surface feel without releasing harmful substances.
Internal Connections and Sealing: Used for flexible connections between precision components such as solenoid valves and flow meters, providing vibration damping and sealing to ensure stable operation of the water circuit system under pressure.
Drainage and Pressure Relief: In some models, they are used in the drainage system to direct wastewater from cleaning or residual water from pressure relief to the drip tray.
Key Performance Requirements
Coffee machines operate under high pressure, high temperature, and steam conditions, imposing strict technical requirements on silicone tubes:
Food-Grade Safety: Must comply with food contact standards such as FDA (U.S. Food and Drug Administration) or LFGB (German Food and Commodities Act), ensuring no odor, no leaching of harmful substances, and preserving the pure taste of coffee.
High and Low Temperature Resistance: Requires a wide operating temperature range (typically -60°C to +200°C or even higher for short periods) to withstand extreme temperature variations from cold water intake to high-temperature steam jets.
High Flexibility and Pressure Resistance: The material must be soft enough to bend and route easily in tight spaces (without kinking) while also having sufficient pressure-bearing capacity to meet water pressure stability requirements during pump operation.
Low Extractability: The material should have low extraction or low leachable properties to prevent contamination of the water circuit system. Platinum-cured silicone tubes typically perform better in this regard, offering higher cleanliness.
Specifications and Customization
Silicone tubes for coffee machines are typically customized according to specific models, with flexible and diverse specifications:
| Customization Dimension | Common Parameter Range / Types |
|---|---|
| Dimensions | Inner diameter ranges from 0.8mm to 9mm, wall thickness typically between 0.3mm and 5mm. |
| Structure | Includes single-lumen tubes, multi-lumen tubes, braided tubes (outer layer braided with polyester fiber for enhanced pressure resistance), and profile-shaped tubes. |
| Color | Usually translucent, but custom colors such as red, blue, black are also available to differentiate circuit functions (e.g., cold water line vs. steam line). |
| Hardness | Typically adjustable between 30A and 80A (Shore hardness) to meet different support or sealing requirements. |
It’s worth noting that for coffee machines with high-pressure pumps (such as espresso machines), silicone tubes with an outer braided layer are generally the more suitable choice, as they provide higher pressure-bearing capacity and burst resistance.