Food grade question

Probably didn't secure the dome lid. Or could have had a bad dome lid gasket.

 

Yeah, so far as I'm aware food grade doesn't vent unless you're unloading (or loading through the discharge pipe.)

 

I use an old milk trailer to haul def. they don't have vents. I have to open the dome every time I dump. He probably just had a bad seal, there isn't really any other way it could leak up there. I doubt he took off with it open.

 

Yep, sure could. Especially if the seal came loose or got twisted as the dome was closed—that could leave a good sized gap even if everything was tightened down.

 

One of the things I get to do regularly is open the hatch on my full tank and drive across a field while draining my load. So I do have some practical experience here.

If the driver failed to secure the hatch he would have gotten a heck of a geyser at first stop sign he met. As the load surged forward and built against the front of the tank "Old Faithful" would have blown. It would be hard to miss.

A gallon spraying out every once in a while argues strongly for seal damage or loosely tightened dogs on the hatch. Just enough to vent some product each surge.

A remote possibility (anything is possible, lazy is lazy) is he got over loaded and the product spilled over the top but the drains were clogged and he didn't bother to take care of it. That would lead to liquid sloshing around the hatch tray and splashing out.

Then there is the combination of the two: Small leak filling the tray which had blocked drains.

In any case his trailer should have been piddling on the road if he was leaking from the hatch or vents and his drains were working.