Can I Use Equity Multiple Times To Invest In Real Estate

[Josh Deel]

So I'm seriously planning to expand my investment portfolio in 2018.  I currently have around $450-500k in equity. My question is, if I were to access this equity via an equity line of credit from "lender A" to use towards the down payment on a multi-family apartment building (for which the additional debt of a million plus dollars would be borrowed from "lender B"), is this "down payment" in the new multi-family apartment deal essentially "equity" that I can access again to use, for example, as yet another down payment on another deal, ad infinitum?   Or, are there limitations to this strategy? Or is the initial equity essentially tied up and unavailable to for subsequent deals until it is paid off to the initial credit equity line lender?  

I appreciate any insights, first hand experience, direction, etc., that may be offered. Thanks in advance!

-Josh