What does HPU stand for?

Fiber Reinforced Plastic, Hoyt, KS - Manufacturer code for watercraft hull identification number (USCG)

Hale Pohaku - Hawaii - Seismograph station code, US Geological Survey (SEIS)

Hand Portable Unit (CGWS)

Hansard's Publishing Union (ROG)

Heater Probe Unit (DMAA)

High-Pressure Unit

Hot Plate Unit (SAUS)

Hours per Unit (TIMI)

Hydraulic Power Unit (MCD)

Hydraulic Pumping Unit (AABC)