Rotaryguy,
NPSHa equals to 4.6ft, is very low but there
is some special designs like double casing vertically
suspended pump that can handle.
In other cases, uses an special eye suction design or
an inductor could be enough.
Other alternative is run a pump with the lowest as possible.
There are several options, which is corrects depends of Q and TDH, Nss, Ns.
Potassium hydrogen difluoride is an unusual fluid.
If you don not have an selected pump material yet. You know it is very corrosive, you should use a metal with PREN more than 40.
Regards,
Luis Lopez