Dear Kees
Dangerous Goods topics are normally not taken into account in "storing" materials. The "issue" is: you need first to define: which regulation you would like to "check"; e.g. ADR, IATA etc.
the "storing" together is related to different "hazardous" aspects (quite long story)
But for "hazardous goods" some solution is possible. BUt here other criterias are used, The "most" common method is using eWM.If you do not use eWM but WM: there is only one "old" method in place which is "outdated" and "only" supported by SAP because of "history"; this is not developped nay more. In most cases here the "amount" topic is ignored; you need to define "somethere" the amount of material A to be stored in storage location; and the may be together wiht material C etc. => for this there is no standard solution available (according to my knowledge).
the eWM topic is discussed here rarely.
Some threads which might be of interest:
A Step-by-Step Guide to Configure the Flexible Hazardous Substance Check
Hazardous Substance Management - Mixed storage Check
. Definition and use of Warehouse Request and Warehouse Order in WM
VM04: data transfering from specification database to table MGEF
Blocking Hazardous Materials for Purchasing with HSM
Comparison between SAP IM- WM –Lean WM – Decentralized WM – EWM
Your topic is discussed onquite low level. In most cases discussion is not taking into account "amount" of material, but physical properties., I am not aware of any kind of "standard" solution to get a solution. Only if you have SAP ERP EnhPack 3 in place and activated the relevaant business function you can use the "flexible" chekc in eWM (and eWM only !!).
C.B.
PS: may be:
No Warehouse Management (WM/EWM) but need to Maintain Hazardous check for Materials Master, how ?
Hazardous Material warning at GR