Ametek Crystal HPC50 [HPC51-1KPSI-BARO] Intrinsically Safe, Single Sensor Handheld Pressure Calibrator w/Barometric Module, 1/4 NPT Male, 1000 psi. The HPC50 handheld pressure calibrator is an intrinsically safe, dual pressure calibrator with options to add an additional two external pressure or temperature modules. The HPC50 pressure calibrator combines the features you love from the HPC40 with improvements like, better battery life an improved display, an extra external module connection, and of course intrinsic safety. The HPC50 series pressure calibrator is fully temperature compensated for pressure, temperature, and electrical measurements from -20 to 50°C.