Re: Water glass? Site glass?

Dan, as John Bush points out later on in this thread, a gauge glass can get plugged (especially if you don't blow it down regularly) and give a false reading. While a try cock can sometimes give a false reading (as John also mentions), the logic is that under most conditions a try cock will give you a more accurate indication than a gauge glass will. Especially if you don't realize that the last crew didn't blow the glass down and you are just giving a brief glance to the gauge glass you can make this mistake. On a steam locomotive, the single MOST important thing you need to know at all times is just where the water is. Accidents have happened when the gauge glass was plugged and the crew didn't notice it...most of the time with spectacular and fatal results. Most crew members did not survive a boiler failure. Those that did didn't live long afterwards. (yes, there were exceptions...but I wouldn't bet my life on a boiler failure being an exception.)

I understand that nowadays the FRA does not require try cocks anymore. But then the requirement is for double redundancy (two independent gauge glasses) and better quality glass. You don't find the old "glass tube" style of gauge glass anymore...which is a good thing. The old ones would break easily, especially in hard locomotive use.