I have a commercial urinal with hard deposits restricting the drain water flow. What is a good way to remove the deposits hopefully without removal or replacement of the urinal.

Long yellow rubber gloves and a scraper

Remove Hard Water Deposits From Your Bathtub . . . No Scrubbing Required. - One Good Thing by Jillee (http://www.onegoodthingbyjillee.com/2012/06/remove-hard-water-deposits-from-your-bathtub-no-scrubbing-required.html)

Hard Water Solutions & Hard Water Cleaner | Lime-A-Way® (http://www.limeaway.com/products/)

BioBlock Biological Urinal Blocks (http://www.cleanacatering.com/default.asp?iId=GHIIHG)

Crete (http://www.brodi.com/crete-heavy-duty-urinal-descaler-odor-smell-control)

I use a product called rydlyme by Apex Engineering; it is an effective, safe to handle, biodegradable rescaled...

I used a pumice stone, as suggested here. Now I have to use it forever, because the porcelain glaze is gone. I don't blame anyone. My hardware store said the same. And I had tried all the chemicals. None of them made a dent.