All official tests standards, whether BS or Kitemark or International, are limited because the results are strictly only applicable to one, or a range of, "typical" samples that was tested. There is an assumption that other similar products will perform in the same way. watch out!.
The condition of the product(s) when used, how it is applied and the real-life circumstances (which will inevitably differ from the controlled test conditions), all affect the actual real life performance. So you should never expect the same results in real life as were seen in an official test.
Why do BS, Kitemark, EN and other international standards for flood products fail to cover Flood Traps?
Specific to flood product tests to BS 851188 2019 the tested product must stand alone. Flood Traps would need to be tested complete with your door and frame in an approved and certified test facility.
Since valid results would be dependent on the condition of the building structure (your door and its frame and how well they are fitted in the building) in addition to DIY product Flood Traps obviously cannot be covered by any standard, so are deemed to be beyond the scope of BS 851188 or any other similar standard.
Flood Traps for your doors and low-level windows provide easy-to-use, effective protection. Even though authorities cannot endorse them as they must be seen to be impartial and Flood Traps cannot be tested to Internationally recognised standards that, for reasons detailed above, are of questionable validty themselves Flood Traps perform very well all the same and are certainly much better than sandbags or doing nothing to keep floods from getting into your property through gaps around doors and windows.
Using Flood Traps as one of a range of flood mitigation products, could be the best low cost investment you ever make.