I am using Honeywell Heavy Duty Pressure Transducer, 150 psi
Can you provide the exact part number. The way I read the data sheet is that there are two models. One has output pressure readings referenced to 0 and the other is referenced to 1 atm (14.7 psi).
How did you derive
float psi = (0.1832844575*sensorVoltage) - 18.75;