ADM3251E have Level 4 EMC license?
The ADM3252E has IEC61000-4-2 ESD to 8 kV contact and 15 kV air. However the ADM3251E has HBM ESD to 8 kV contact and 15 kV air. IEC61000-4-2 ESD and HBM ESD are very different. The ADM3251 does not provide the required level of protection you require without the addition of external protection components. In order to achieve the required ESD you will have to either use the ADM3252E or use and eternal protection component with the ADM3251E. Note neither of these parts were characterized for EFT. The evaluation boards were not certified like the ADM2795E Evaluation board.
Bourns have recommended circuit protection devices for RS-232:
If you do not require IEC61000-4-5 Surge Immunity the CDSOD323-T105C may only be needed, the addition of the TBU and the GDT are typically only for Surge. I would advise putting a 0603 0 Ohm link between the terminal of the TVS and the pin it is protecting. This will allow for a resistor if required, during testing, to ensure the that the TVS turns on before the ADM3251E pin turns on. This resistor should be large enough to cause a voltage differential between the TVS pin and the ADM3251E pin, but it should be low enough not to cause issues (RC time delays) in your circuit. I would typically start with 10 Ohms. Also ensure that this is a pulse proof resistor.
This may also allow you meet your EFT requirements. Please let me know if you have any questions.