Salam bro, have a read here:
It is not recommended to donate blood while fasting unless there is an absolute necessity to do so.
Drawing lots of blood may make a person weak and thus he may be forced to break his fast. So indulging in such an activity is not at all recommended as we are advised to keep our fasts intact as best as possible.
Moreover, there are scholars who are of the opinion that drawing lots of blood would invalidate one’s fast. This is the view of Imam Ahmad. However, Imam Ash-Shafi`i and others are of the view that drawing of blood by itself does not break the fast, but one is not encouraged to do so as it may render a person weak.
The ruling, however, is different when faced with an emergency. Such is the case when one must donate blood to save a person’s life; in this case one must do so without any hesitation; it is better for him to break his fast if he has to than continuing his fast.
Another exception: If a person is exceptionally strong and is certain that donating blood would not render him weak at all, then there is no harm for him in donating blood, according to the view of Imam Ash-Shafi`i and others.
In conclusion: Each person should consider his own state of health before embarking on this action.
Donating Blood while Fasting - IslamonLine.net - Ask The Scholar
Note: this is not Hanafi view but you can say that Hanafi view would be along the same lines even invalidating the fast. Insh’Allah if I come across anything I will post it.