Is it correct to read ‘1830 hours’ as ‘eighteen thirty hours’? And I suppose the word ‘hours’ is always needed after ‘1830’ in this way of writing times?
One more thing is I wonder if it is okay to use ‘times’ in plural to refer to ways of writing time (I saw this in a book on how to write business correspondence).
It is correct to read i like that, but ‘hours’ isn’t always added – quite often it’s assumed. It depends on whether or not it is obvious from the context or other information that you are referring to time.
If you mean is something like this correct:
“Write out the times shown on the clock-faces”, then yes, it is standard.
Yes, you would say it like that. When writing it wouldn’t always be necessary to add ‘hours’’ because it would be clear from the context that you are referring to the time.
‘Time’ is obviously used in the singular as in: Can you tell me the time, please? But ‘times’ can be used when you are referring to something like ‘times of the trains’ ‘at different times of the day’ and as in your text when you are talking about ‘times’ in general.
I’d think such type of expression is used in military organizations, and reads ‘eighteen hundred and thirty hours’ for the accuracy, or the abbreviate form as you suggested. Otherwise and commonly, it should be, as everyone knows, 18:30, and reads ‘eighteen thirty’ without “hours”.