https://github.com/Buuz135/Industrial-Foregoing/blob/432e14276c69de527e1d3ed4ff7525d74b83890e/src/main/java/com/buuz135/industrial/utils/ItemStackUtils.java#L190-L209

There are still some issues with this. Let me know if you want me to open a new issue about this.

First issue, if the machine tries to move less fluid than the cell will accept (it only accepts 1000, and returns 0 otherwise) the cell is moved into the output slot.

Second issue, if there is more than 1000mb in machine all the fluid is used up, even though the cell returns that only 1000mb was used.