Bacharach H25-IR User Manual

H25-IR 

Calibration 

 

Instruction 3015-4342 

23

 

Internal calibration uses the instrument’s built-in leak source. Properties of the leak source (i.e. gas type, 
leak rate, temperature coefficient, and specification temperature) are entered at the factory and do not 

need to be changed by the operator. 

The properties of the leak source along with the current internal temperature of the instrument are used 
to compute the actual leak rate when a calibration is requested. This number is displayed as the “target” 

value during calibration. A spring switch located in front of the CAL Port ensures that the probe is kept in 

place for the duration of the calibration process. Calibration will fail if the probe is withdrawn too early in 
the process, or if the computed parameters deviate from the stored factory calibration by more than 20%. 

1.  Turn ON instrument and allow it to complete its 120 second warm-up. 

2.  Press the front panel CAL button to display the Calibration screen. Note that the display must be 

reading a leak rate of “0.00” when the CAL button is pressed; otherwise, the message “LEAK 

RATE MUST BE ZERO TO CALIBRATE” will appear. If necessary, press the ZERO button to 
zero the display before pressing CAL. 

 

 
 

 

3.  Ensure that the instrument is set up for internal calibration as indicated by “INT CAL” being 

displayed at the bottom-right of the display. If “EXT CAL” (external calibration) is displayed, 

perform the procedure in Section 3.1 Selecting Internal or External Calibration and set the Cal 

Type to Internal. 

4.  Insert the probe tip into the CAL Port within 10 seconds 

after pressing the CAL button. Be sure that the probe tip 

makes contact with the spring switch. At this time the 

calibration process should automatically start.  
 

The top number of the Calibration screen shows the 

“target” value (leak source rate), while the bottom 
number shows the current measured value. Keep the 

probe tip firmly against the back of the port for the 

duration of the calibration process, during which time the 
instrument is calibrated at both a high and low flow rate.  

If the probe tip looses contact with the spring switch before the 
calibration process completes, the message “CAL ABORTED” is 

displayed. At this time press any key to retain the previous 

calibration curve and return to the Data Display screen. 

5.  After a successful calibration the new calibration data is saved 

and the message “CAL OK” followed by “WITHDRAW PROBE 

FROM LEAK SOURCE” will appear. 

6.  Withdrawing the probe causes the display to switch back to the 

Data Display screen. Note, however, if the PCHK Mode is set to 

AUTO (refer to Section 2.4.7 PCHK Mode), then a pressure check 

is performed prior to the display of the Data Display screen. 

 
NOTE:

 After being calibrated the instrument is automatically 

placed into its Search mode. 

 

Oz/yr 

R134A

SETUP 
INT  CAL 

WITHDRAW PROBE

FROM LEAK 

SOURCE 

Oz/yr 

R134A

SETUP 
INT  CAL

Oz/yr 

R134A 

SETUP 
SM  SRCH

Oz/yr 

R134A

SETUP 
INT  CAL

TARGET 
O/YR 
R134A 
MEASURED
O/YR

Oz/yr 

R134A 

SETUP 
INT  CAL 

TARGET 
O/YR 
R134A 
MEASURED 
O/YR 

INSERT 
PROBE 

 

 

 

PCHK