The SmellX odor trap seals the urine path of the BioTioo with a floating ball: passive, power-free, and fully disassemblable. It sits between the separation insert and the 10-liter urine tank, at the critical point of the system. Because ammonia odor develops in the tank over time; without a seal, it would rise directly into the vehicle through the filling opening. This one component was designed by us in Überlingen to operate without a rubber membrane, without power, and without replacement intervals. The principle is patented and is now standard in every BioTioo series.
How the ball seals
When urine flows, buoyancy lifts the ball from its seat and opens the way into the tank. When the flow stops, its own weight lowers it back onto the sealing surface. The seal closes both openings of the tank, the one for liquid and the one for air. This way, urine only flows in, and the tank air remains enclosed; the room air stays clean, regardless of the fill level. Why this one seal largely determines the odor profile of the entire vehicle is explained in Why a separation toilet doesn’t stink.
The seal closes tightly; it does not cover anything. Some systems rely on fragrances in the urine path that only mask the odor as long as the fragrance is fresh. The floating ball instead blocks the path itself, permanently and without consumables.
The SmellX consists of three core parts: the floating ball, the ball seat with the two openings, and the siphon body as the housing on the tank. You separate all parts with a simple screwdriver or a similar pointed tool. No special tool is necessary. This disassemblability is a design goal, not an add-on. Every sealing surface must be accessible for cleaning, even inside the ball seat.
The ball seals airtight and leak-proof, even when tilted or during off-road vibrations. Electronics, sensors, or a return spring are not part of the component. For context: the seal secures only the urine path. The solid waste container does not need such a component because it is a closed, drying chamber (the basic principle of separation explains the function of the separation toilet).
Why a ball and not a rubber part
We decided against any design on the urine path whose sealing force comes from an elastic rubber part. A membrane closes by contracting with its tension after flow. A beak check valve presses its lips together by inherent tension. Both principles seal reliably when new, but rubber fatigues or sticks over time. That is why suppliers of such systems offer the rubber part as a replacement part.
We did not want that replacement part in our product. Gravity and buoyancy do not diminish; the ball principle does not experience fatigue like rubber. This eliminates the need for spare parts on board, and cleaning replaces part replacement. A full comparison of all three designs is in our design decision on the urine path. How the power-free seal works together with the optional 12-V fan is explained in Passive sealing.
Cleaning and descaling are part of it
An honest point upfront: urine forms crystals on every component over time, in every toilet and every sealing system. The SmellX does not eliminate urine scale; it makes it accessible.
The routine is:
- Remove: detach the seal when emptying the urine tank.
- Disassemble: separate ball, seat, and siphon body without tools.
- Rinse: rinse all parts with warm water and dish soap.
- Descale: soak parts in citric acid solution or clean with dish soap until deposits dissolve.
- Reassemble: dry and reassemble, then reinstall.
In practice, it has proven effective to rinse briefly at every tank emptying and descale every few weeks. The powder is available at any drugstore. The seal does not require special cleaners. How to keep deposits small from the start is explained in Avoiding urine scale.
How to disassemble, clean, and reinstall the SmellX is shown step-by-step by Sascha in this video: https://www.youtube.com/watch?v=kvy488ngmY8
Availability
The SmellX is standard in every BioTioo 2.0 and BioTioo 2.0 RL-Motion series and is also available as a separate module, both as a spare part and for retrofitting. It fits all BioTioo urine tanks and many dry and composting toilets with wide-neck canisters according to DIN 96. We offer a 3-year warranty on the bowl and lid of every BioTioo, plus a 60-day return policy. You can find all models with the seal in our overview of composting toilets.
