[immortality]

I saw this sentence at an article and is very important to my simulation.
since I'm not a native speaker of english,could anyone say to me what does this sentences mean precisely?

"In order to maintain the flow of compressed air,the left-side end of the cell has to be opened at the very moment the primary shock arrives there.the compressed air is then pushed out into the outlet port from where it will flow to the engine"

what does "at the very moment" mean?does it mean "later" or "before" or "exactly at that time"?
and in second sentence it pretends to say that the shock forces fluid flow out,correct?

[Aeronautics El. K.]

"at the very moment" means "exactly at that time".
However, I don't know if your second question can be answered exactly without any further information on the context in which it is written.