Teledyne HPM-2002-OBE User Manual

Page 10 of 39 

The HPM-2002-OBE will automatically enter the Run mode upon start-up. This is the mode for normal 

operation and the mode in which the instrument will spend most of its time. In the Run mode the HPM-2002-

OBE will continuously monitor the pressure, update the alarm conditions, and update the display about ten 
times a second. 

Optimal performance of the HPM-2002-OBE is achieved by performing in situ adjustments to the 

calibration coefficients in the Cal mode. There are three calibration coefficients. These are the zero coefficient, 

the midrange coefficient, and the atmosphere coefficient. Once a tube has been fully calibrated the midrange 
coefficient should never need further adjustment, but it may be helpful to adjust the zero coefficient or the 

atmosphere coefficient under certain circumstances.  The CAL MODE presupposes that the operator is 
applying a known pressure of the correct gas composition (see GAS MODE). The factory calibration points are 

800 Torr, 7 Torr, and < 10

-6

 Torr. The user’s calibration points are not required to be exactly those values, but 

should be somewhat close, and must be within the ranges shown in the following figure. The HPM-2002-OBE 

detects the voltage signal within the sensor tube, which is converted and displayed as a pressure reading. The 
resulting pressure reading determines which of the three coefficients will be adjusted.  

 

 

The operator action is the same for adjustment of all three of the coefficients, except that he must apply the 

proper calibration pressures according to the calibration point he is about to adjust. To adjust a calibration