Mister Dungun.Regarding API Publ. 1025A section 5 really recomeds(not mandatory)and is not for Hydrants, is for fixed monitors. The minimun distance is from the equipment edge. However, previously radiation study should be done in order to be sure the operator integrity. It is not posible keep the minimun recomended distance, remotely activated monitors can be used or pasive protection like a shield could be designed. Please see API PUBL. 2510 parag. 10.3.2.2.1, API RP 2001 Parag. 6.2.6 and NFPA 59A or NFPA 24 and NFPA 1 HAND BOOK for Hydrants.
Regards