Hi Does anyone know how to decode the numbers on the fisher gas cartridges to find out the expiry date? I've seen the sales blurb that they last 5 years but you need to know when they were manufactured for that to be of use. These are the 3 gas cartridges bought today: 2020 001680 2020 001678 2027 001745 And two I bought last year are... 351 001509 951 001509 Cheers in advance Rob