JIG recently issued Bulletin 104 with regards to EI 1584 4th edition.
For current users of EI 1584 3rd edition hydrant couplers and pit valves, there are no changes required as 3rd edition equipment are recognised to meet with the qualification requirements of the 4th edition. Please see below extract from the 4th edition on the updates in the latest edition.
JIG Bulletin 104 updates on EI 1584 4th Edition Equipment