Technical term question

[abc_071]

Hello,
I am engeneer with bachelors degree in HVACR from Bulgaria (Technical university of Sofia- http://www.tu-sofia.bg/ENG/index.html). Now I'm at the begining of my masters degree course and I've received a task to create and prepare some material for our sertification centre for HVACR technicians. Among them is an educational video made by Sporlan,I'm making subs for. I'm very sorry about the symplicity of my question. I encounted a difficulty with one preticular phrase - "gas work". I will be very thnakfull to recive some kind of an explanation of this phrase, because it can't be translated literally. It must be considerd in the context of the content. That's why I'm giving you the timings for the moments of appearance of the phrase and a link to the video: 00:11:27 and 00:12:08; http://sporlanonline.com/PTVideo.htm
Thank you very much for the help!

[Tayters]

He's saying 'guess work'.

Cheers,
Andy.

[abc_071]

Thank you very much, now I understand why it wasn't clear to me. Thank you one more time.

[Tayters]

No problem. The video is very informative as well.

All the best,
Andy.