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While I don't know exactly what safety mechanisms they use, they do certainly have at least two layers of protection against over dosing. In a system like that one the primary layer of protection is always that the maximum dosage rate isn't really all that high, so even when it fails on maximum feed rate, there should be time for you to notice that something is going on before any permanent damage is done. There is also always at least one addition layer beyond that, typically including things like disabling the acid feed if the PH is not observed to change in response to acid feed over some longish period of time.
Note, we don't recommend ORP based chlorine regulation, such as used by the Intellichem, and several similar product from other manufacturers, for use with a residential pool. ORP is simply not reliable enough to be suitable for use with consumer systems, though it does have it's uses in commercial systems with professional oversight.