Patent ID: 7739895

Claim:
A method of determining whether a scale in a fluid handling device needs to be calibrated, comprising: weighing a storage tank of a fluid at a first time with a scale; transferring the fluid from the storage tank to an area of known volume; weighing the storage tank at a second time with the scale, after fluid has been moved to the area of known volume; determining a pressure of the fluid in the area of known volume with a pressure sensor; calculating a temperature of the fluid in the area of known volume with the determined pressure; calculating the weight of fluid in the area of known volume based on the calculated temperature; comparing a difference in weight of the storage tank between the first and second weighing times with the weight of the fluid in the area of known volume; and sending a first signal to a user indicating a calibration of the scale is not needed if the difference between the compared weights of the fluid is within a predetermined range.