Most dairy barns (if they are grade A) have a concrete floor. These tanks are not terribly heavy but they are not featherweight either. I find that folks end up sliding them across the concrete floor and just wearing the bottoms very thin. All it takes is a small hole to break the insulating seal. These are really just big thermos jugs. It then " leaks"..... not really the nitrogen but just doesn't insulate well so that the nitrogen evaporates off quicky.
When the nitrogen is gone, theoretically in 90 seconds your semen is thawed out and very quickly dies.
I learned a sad lesson about tank upkeep.
Last fall, our dairy goat club sponsored a buck collection. One of the goat owners could not stay until it was all processed. So I told her that I would take her tank home and she could pick it up from there. She didn't do that. I checked on it and had it filled when the guy came around a few days after I brought it home. I then promptly forgot about it. The nitrogen guy comes around every 6 weeks. A month passes, my tank is still in the cardboard box I bought it in 5 years ago and well protected, but hers is an older used tank that looks like it has been kicked around a bit. One day, I pass by and see it and remember that she was supposed to have picked it up over 6 weeks ago...... I check it and------ totally dry. About $600 worth of semen dead. I am just sick, she is mad as all get out because I didn't check it regularly and I am looking like the bad guy. I did not pay to replace all that semen..... I am still not her favorite person and I only feel slightly guilty for offering to help out in the first place.
I did give her some semen from one of my bucks that she liked. Then I found out several weeks later that she had somebody else's semen in there, too.
So now, I handle only my tanks and I check the nitro level every two weeks.