When You Cannot Prove There Was Sixty

An incident happens. Something entered a vessel that should not have, and the first question everyone asks is whether there was enough volume to nullify it.

Often that question cannot be answered — and the situations where it cannot are predictable enough to plan for.

The cases where the measurement is unavailable

The sources enumerate them, and they map cleanly onto plant reality:

That third row is the one worth designing against. Most real incidents are not "we know 4kg went in"; they are "the line ran for some period with the wrong feed and we are reconstructing it". Once the tank is emptied, the reconstruction is all you will ever have.

The two decisions people merge

Here is the part that catches plants, and it is worth stating plainly before the detail.

Clearing the product and clearing the equipment are separate decisions. A batch can be released on the strength of a doubt while the vessel it was made in still requires treatment.

The reasoning for the split is precise, and it runs through where the doubt actually sits:

• For the food, the prohibition is certain and the nullification is doubtful — so a presumption of permissibility does not carry it.
• For the vessel, the position is the reverse on one view: perhaps the material was nullified in the liquid, in which case the vessel never absorbed anything forbidden at all — so the presumption can carry it.

That view permits the vessel. It is not the only view, and the dispute is live.

The three positions

Worth knowing all three, because which one your certifier holds determines what happens to your tank.

1. The vessel needs no hagalah — even for an unlike mixture — on the presumption above. Though even here, a twenty-four hour wait is required before use.
2. The vessel needs hagalah regardless. The Chazon Ish argues that where we permit a mixture on a doubt, the vessel still requires it — we are stringent in a rabbinic doubt where the thing has a future permit. His practical point is blunt: kashering one vessel is not a hardship the way kashering many would be, and cooking in a doubtful vessel afterwards means needing to permit each subsequent batch on a rabbinic doubt. Why enter a doubt for nothing?
3. The vessel follows the food. The dissent holds you cannot separate the two — if the dish is permitted, the vessels are permitted, because the law of the vessel cannot be prised apart from the law of what was in it.

Notice what the Chazon Ish's argument really is. It is not that the vessel is probably forbidden. It is that the cost of resolving the doubt is one kashering, and the cost of carrying it is a permanent doubt attached to everything that vessel touches afterwards. That is a cost-of-carry argument, and it is one a plant manager will recognise immediately.

What to do while the evidence still exists

All of the above is about what happens when the measurement is gone. The useful conclusion is about the window before that.

Do not empty the vessel. This is the single most valuable instruction on this page. Almost every case above becomes answerable if the material is still there and still measurable. A tank drained to "make the problem go away" converts a solvable question into a permanent doubt.

And capture, at the time:

• The vessel's contents by volume or weight at the moment of the incident, not at shift end.
• What entered, and the best available bound on how much — including the period over which it could have been running.
• Whether anything was transferred out afterwards, and where it went.
• Whether the material was hot, which decides whether the vessel is in question at all.

Four facts, none of which requires a decision from anyone on the floor. They are the difference between a question your certifier can answer in an hour and one that costs you a tank.

Raise it immediately for the same reason set out in process parameters that leave no trace: these situations are frequently recoverable, and the options narrow as the evidence disappears.

For the underlying rule, see bitul. What your own incident requires is a question for your certifying rav — and the vessel question is one to ask explicitly, rather than assume it travels with the batch decision.