Can I bring a soda siphon and CO2 cartridges?

[GreenBottle33]

I've posted this question elsewhere online already so apologies if you've happened upon it already. Canvassing further opinion here.

 

I'd like to make sparkling water using tapwater, to use as a mixer. I'll be traveling by coach so a light load is important, and I won't be camping near the Co-op. I'm considering buying something like this siphon and accompanying CO2 cartridges:

 

https://www.nisbets.co.uk/olympia-soda-siphon-black-1l/ce341

https://www.nisbets.co.uk/isi-soda-siphon-co2-charger-bulbs/gh056

 

My only concern is that the cartridges might be mistaken for nitrous oxide. Obviously I'd bring them in their own box, which will hopefully arrive sealed.

 

I've only been to Glastonbury once before, and security was fairly lax from what I remember. But I wonder if these would show up on a metal detector, and how amenable security would be to my demonstrating they are genuinely CO2. I fear I'd get short shrift and they'd be quickly confiscated.

 

I am minded to just chance my arm but thought I would check if anyone here has any thoughts. Thanks!