Changing scent: rinse, purge, then refill
Changing scent in a diffuser without mixing the fragrances takes four steps: switch the unit off, empty and rinse the bottle, purge the circuit, then pour in the new PURRA Signature Refill 100 ml. Without that purge, the fragrance left in the nebulisation head layers itself over the next one.
A purge cycle is the passage of a maintenance solvent through the nebulisation circuit, intended to carry away the fragrance that stays in the head and the dip tube once the bottle is removed. It is not a comfort clean: the PURRA manuals prescribe it at every change of scent, just as they prescribe screwing the bottle down to the stop. If the choice of fragrance itself is still open, our guide to scents room by room covers that question first.
The essentials
- The fragrance does not stay in the bottle alone: it stays in the nebulisation head and the dip tube, which changing the refill never touches.
- The purge cycle: 2 to 3 ml of isopropyl alcohol at 70 % in the empty bottle, then 5 to 8 minutes of operation on the strongest setting.
- On the PURRA X300S and G300, the internal aluminium bottle unscrews, rinses and refills: it is never thrown away. On the PURRA C30, the 10 ml bottle is replaced.
- A Signature Refill of 100 ml lasts 625 hours of operation on setting I, 400 on setting II and 200 on setting III, which is about 78, 50 and 25 days at 8 hours of diffusion a day.
- No other liquid goes into the unit, and never water.
Why the old scent lingers after a refill change
The old scent lingers because changing the refill only empties the bottle. The concentrated fragrance rises through a dip tube up to the nebulisation head, where a nozzle breaks it into micro-droplets. Those two parts stay soaked while the bottle is already gone.
It is a matter of dead volume, not of cleanliness: a circuit that has diffused a woody note holds concentrate in its finest passages, and the first breath of the next scent puts it back into circulation. Top notes, the most volatile, give the mix away first; base notes, heavier, cling longest to the walls.
The internal bottle is rinsed, not thrown away
On the PURRA X300S and G300, the refill does not screw on directly: it is poured into an internal aluminium bottle, housed behind a hatch, which is a reusable container. That bottle unscrews, empties, rinses and refills, and it is the one used for the purge cycle. Hence the rule: it is never thrown away.
The PURRA C30 works differently: its 10 ml frosted glass bottle is replaced, not refilled. For that reason the box contains a second, empty 10 ml bottle whose only purpose is this, and which will hold the solvent for the cycle. Keeping it is the single precaution to take when unpacking.
This difference shapes how often one changes scent. With a Signature Set, six 10 ml bottles allow six successive scents on a C30. With a 100 ml refill, you first empty what remains in the internal bottle, and it is that remainder which makes it worth waiting for the bottle to run out.
How to purge the circuit before the new scent
The purge takes five steps and needs only an empty bottle and isopropyl alcohol at 70 %. Allow 5 to 8 minutes of operation, plus the time for the head to dry in the open air. Ventilate the room, keep any flame away, do not inhale the mist during the cycle, and never run it inside a closed vehicle.
- Switch the unit off and wait two minutes, so the fragrance left in the nebulisation head falls back. Unscrewing too early causes a spill.
- Unscrew the bottle. Empty and rinse it if it is the internal bottle of the PURRA X300S or G300; on the PURRA C30, set it aside and take the empty bottle supplied in the box.
- Pour 2 to 3 ml of isopropyl alcohol at 70 % into the empty bottle, then screw it back onto the nebulisation head down to the stop.
- Run the unit for 5 to 8 minutes on the strongest setting, room ventilated, then switch it off.
- Remove the bottle, let the head dry in the open air, check the seal, then fit the new scent.
Checking the seal is not a precaution of principle: cracked or deformed, it lets fragrance escape and makes the mist drop, which is easily mistaken for a clogged circuit. A PURRA Maintenance Solution is announced as in preparation in the manuals; until it is available, isopropyl alcohol at 70 % remains the instruction. For routine upkeep, our article on cleaning a fragrance diffuser also covers the exterior and the touch control.
C30, X300S, G300: what changes from one model to the next
The model changes neither the principle nor the solvent: it changes the bottle format and the way to reach it. PURRA is a French brand of home fragrance diffusers using cold nebulisation, whose units share the same nebulisation head and the same six scents, available in two refill formats.
| Model | Coverage | Refill format | Changing step |
|---|---|---|---|
| PURRA C30 | 10 m² | 10 ml glass bottle | The bottle is replaced; the empty bottle supplied serves the cycle |
| PURRA X300S | 100 m² | 100 ml refill poured into the internal bottle | The internal bottle is emptied and rinsed, and also serves the cycle |
| PURRA G300 | 180 m² | 100 ml refill poured into the internal bottle | Same step as the X300S, best set on a closing day in a business |
The PURRA C30 uses the 10 ml format and that one only: no 100 ml refill fits it. The PURRA X300S and G300 are currently offered on pre-order, shipping from 15 November 2026.
Two units, two ways to change scent. The PURRA C30 covers 10 m² and costs 89.90 €: you change scent by replacing a 10 ml bottle, which makes it the simplest unit for frequent alternation. The PURRA X300S covers 100 m² and costs 199.90 €: its internal bottle rinses and refills. Prices read on purra.fr on the day of publication.
Which scent transitions call for the most care
Every transition goes through the same cycle, but they are not all heard the same way. At PURRA, we advise taking particular care over the move from one olfactory family to another: it is the contrast of register that makes a remainder noticeable, far more than the quantity of fragrance left in the circuit.
The six scents fall into three registers. Brise Marine, "a wave of pure, bracing freshness", and Brume de Cologne, "a fresh, timeless note", hold the fresh register. Éclat d'Agrumes, "a sparkling, luminous blend", holds the citrus register. Musc Blanc, "a refined, elegant trail", Éclat de Jasmin and Bois Envoûtant, "a warm woody essence", occupy the warm register.
Going from one fresh note to another fresh note passes without a jolt. Going from a woody base to a citrus top note is the most demanding transition, and it is the one where it pays to let the head dry longer before fitting the bottle back. A Signature Set brings the six scents together in 10 ml bottles and lets you try those sequences on a C30 before committing to a 100 ml format.
When to change without wasting a refill
The most economical moment to change scent is the end of the bottle: nothing is thrown away and the purge cycle falls into place naturally. A 10 ml bottle lasts 333 hours of operation on the gentlest setting, which is about six weeks at 8 hours of diffusion a day.
With the 100 ml format the calendar is wider: 625 hours of operation on setting I, 400 on setting II and 200 on setting III, which is about 78, 50 and 25 days on the same basis of 8 hours of diffusion a day.
Keeping a second scent in reserve avoids being caught short, in the logic of an object you refill rather than replace. The same reasoning guides the choice between giving the unit and giving the scent, set out in our article on the diffuser or the set of scents.
Frequently asked questions
Can you change scent just before having people over, or should you do it earlier?
Better the day before. The purge cycle takes 5 to 8 minutes of operation, then the head has to dry in the open air, and it is run with the room ventilated and any flame kept away: it is not a step to squeeze between two preparations.
Changing scent on the same day is still possible, but the room has to be ventilated during the cycle, which sits badly with a house you have just warmed for guests. The comfortable order is therefore purge and reassemble the day before, unit switched back on in the morning. If the scent already in place suits, the simplest option is to change nothing and raise the intensity by one setting.
Does it bother a guest to smell two fragrances layered over each other?
Yes, and that is the whole point of the purge cycle. A guest walks in with a fresh nose: they notice the layering that the occupant no longer registers. The 2 to 3 ml of isopropyl alcohol at 70 % used in the cycle exist precisely to avoid that muddled impression.
Olfactory habituation explains the gap: you stop perceiving a smell you are continuously exposed to, while a visitor identifies it on the doorstep, a phenomenon set out in our article on the smell of your own home you no longer notice. Two fragrances from distant families stand out faster than two fresh notes. That is the case where the purge deserves to be done without rushing.
Can you give a scent to someone who already has one in their diffuser?
Yes, as long as you know the person will have to run a purge cycle before fitting it. A Signature Set at 24.90 € brings the six scents together in 10 ml bottles, which lets the recipient change over once the bottle in use runs out.
The format matters as much as the scent: 10 ml bottles screw onto the C30 and onto that unit alone, while the 100 ml refill is poured into the internal bottle of the X300S and G300. Checking the model before buying avoids an unusable gift. Giving several scents rather than one also leaves the person free to set their own timing.
Do you need a purge cycle even when you put the same scent back?
No, the cycle is not required when the scent stays the same: filling the bottle is enough. The PURRA manuals prescribe it at every change of scent, and as periodic upkeep of the circuit, with 2 to 3 ml of isopropyl alcohol at 70 % and 5 to 8 minutes of operation.
A circuit that is never purged ends up giving a weaker mist, and that is the second cause of missing mist after a badly tightened bottle. The seal on the nebulisation head is checked on the same occasion: cracked, it lets fragrance escape. Filling itself is done with the unit switched off, after two minutes of waiting.
Do you have to buy a new bottle every time you change scent?
No. On the PURRA X300S and G300, the internal aluminium bottle is reusable: only the Signature Refill of 100 ml, at 24.90 €, is bought again. On the PURRA C30, it is the 10 ml bottle itself that is replaced, and the empty bottle supplied in the box stays reserved for the cycle.
The cost of a scent change therefore comes down to the price of the refill, plus a few millilitres of isopropyl alcohol at 70 %. A 100 ml refill lasts 625 hours of operation on setting I, which is about 78 days at 8 hours of diffusion a day. Shipping is free from 49 € to France, Switzerland and Monaco.
Does changing scent often damage the unit?
No, provided the purge cycle is run every time. That is precisely the step the manuals provide for, with 5 to 8 minutes of operation and the head left to dry in the open air. What tires a diffuser is a circuit that is never purged, not the number of scents.
The seal on the nebulisation head is the part to keep an eye on: it is checked at every cycle, and a cracked seal makes the mist drop. The units are covered by the legal guarantee of conformity of 2 years. Beyond that: no household cleaner, no abrasive, and never water in the circuit.
Once the circuit is purged, the Signature Refill of 100 ml is poured into the internal bottle of the PURRA X300S and G300, and the new scent starts on a clean circuit.
Article published on 6 October 2026 by PURRA.