The Model 3750 Heavy Duty Hand Pump is a portable, self-contained pressure generator capable of producing and controlling calibration test pressures into pneumatic and hydraulic gauges. Calibration is achieved by comparing the device under test with a connected reference pressure indicator. The reference pressure or vacuum is manually generated by squeezing the scissor-action handles on the pump and making pressure adjustments using the coarse and fine volume adjust knobs. If the hand pump is purchased with the hydraulic reservoir, then hydraulic gauges and instruments can be calibrated hydraulically up to 6,600 psig using the Model 3750 or up to 10,000 psig with the Model 3750-HPDX