A Teflon ring for two critical points
This ring is one of the few items in the Rocket catalogue that is needed in two different places: on the boiler's safety valve and on the steam and water valve. Both are points where hot steam under pressure tries to get past a threaded connection and must be prevented from doing exactly that.
There is a reason why it is Teflon rather than rubber that sits there: the safety valve connection is permanently hot, and an elastomer would become hard and cracked there within a few years. Teflon stays stable, but loses a little height each time it is fitted. The part number is A449904331.
When it is due
A damp rim appears on the safety valve or the steam valve and comes back after wiping. The connection hisses quietly when the machine is at operating pressure. A white ring of limescale spreads outwards from the connection. Or the connection has already been opened once – then the ring should be replaced before it is closed again.
At a glance
| Type |
Teflon ring |
| Location |
Safety valve and steam and water valve |
| Fits |
Rocket machines with this connection – the documentation does not give a model list |
| Scope of delivery |
one ring |
| Part number |
A449904331 |
| Design |
Teflon (PTFE); dimensions and thickness are not documented |
| Installation |
Installation by a specialist recommended |
| Brand |
Rocket |
Important for installation
Both installation points carry steam under pressure. The machine must be disconnected from the mains, completely cooled down and depressurised. In addition, the following applies to the safety valve without exception: the valve itself is never readjusted, closed off, bypassed, drilled open or blocked, and its blow-off path must remain clear. If you are only changing the seal, leave the valve itself as a component alone. We deliberately do not provide step-by-step instructions here.
Who it is for
For workshops and for experienced owners who renew the sealing surfaces when servicing the boiler or the valves. If you are not sure whether your ring is this one, measure the old one and send us the measurement together with the serial number – at these two points, guessing is the more expensive option.
What goes with it
Frequently ordered together: the Safety valve Appartamento TCA, the Safety valve R9, the Pipe to the safety valve and the O-ring for the steam and water valve. Everything else in Rocket accessories and spare parts and in the spare parts.
The Teflon seals in the Rocket catalogue
We stock five Teflon seals individually. They look similar and sit in quite different places – the part number decides, not the shape:
From our workshop in Bern and Zurich
As a rule, we only touch the safety valve when we have to – and when we do, we change the Teflon ring as well, even if it still looks good. A ring costs less than a franc's worth of working time; opening the valve a second time costs considerably more. This is our routine, not a manufacturer's requirement. We then do the test extractions with the Nutty Delight, the Cozy Chocolate or the Very Nutty. The selection can be found under Coffee beans.
Returns excluded
Spare parts are excluded from exchange and return. They are procured specifically for each order and cannot be resold after installation or a trial fitting on the machine. Therefore, check the model, year of manufacture and serial number of your machine before ordering – or drop us a quick message and we will clarify the fit together. Your rights in the event of defective goods remain unaffected.
Frequently asked questions
Is this an electrical part?
No. It is purely a seal made of Teflon, with no electrical function.
Is it really the same ring for both points?
Yes. The documentation lists A449904331 for both the safety valve and the steam and water valve. It is one item, not a pair.
What are the ring's dimensions?
Inner diameter, outer diameter and thickness are not documented. Send us the serial number of your machine and we will check the fit.
May I readjust the safety valve when changing the ring?
No. A safety valve is never readjusted, closed off, bypassed, drilled open or blocked, and its blow-off path must remain clear. If it blows off, that is the signal of a problem, not the problem itself.
Can I see the part in your showroom?
Yes. We are in Bern at Gerberngasse 44 and in Zurich at Hagenholzstrasse 50b. Let us know shortly beforehand and we will have the part ready for you.
Questions about the fit? Write to us at [email protected]. We deliver across Switzerland and to Liechtenstein in 2-4 working days.
