PROCEDURE

Draft UUT Calibration of the Pressure Transmitters

Method 1

1) The equipment was connected as shown in Fig. 4 with EJA430A pressure transmitter as the UUT.

2) The value of UUT was set at its lowest calibrated value. The value was entered in in Column 2 of Table 3.

3) The tolerance of UUT at this value was calculated and entered in Column 34) The value of the Pneumatic Pressure Standard was adjusted so that the UUT reads the

value set in step 2. The value of MSU was read and entered as first run in Column 4.5) The value of UUT was set at the next reading and continued with step 3 to 4 till the

maximum reading of UUT was reached. The first run was completed.6) Steps 2 to 4 was repeated. Another colleague performed this. This gave the second

run. It was repeated in this manner for the third run to complete Table 3.

Method 2

7) The calibration was performed in reverse way by fixing the value of MSU and the corresponding reading of UUT was taken. The result was tabulated as Table 4.

Hysteresis

1) The equipment was setup as Fig. 4.2) The MSIMSU was set at the low range of UUT. The UUT reading was noted.3) The MSU reading was increased in steps and the UUT reading was recorded at each

step.4) This was continued until High range of the UUT was reached.5) The MSU was then decreased in steps and the UUT reading was recorded at each

step.6) This was continued till Low range of the UUT was reached.7) The data as tabulated and graph was plotted.

Five Point Calibration of Pressure Transmitter

1) The instruments was connected as shown in Fig. 4.2) The MSU was adjusted such that the UUT read the first point. In the case of pressure

transmitter, the first point on the output was 4mA which corresponds to an input of 0kPa. The required value of the MSU was read and tabulated.

3) Then, the point was checked, that was 50kPa and adjusted the MSU so that the UUT gave this reading. Similarly proceeded till the maximum value of the fve points that is 200kPa was reached.

4) The five point calibration curve was plotted for the pressure transmitter. The output error curve for pressure transmitter against the output reading was plotted.

CONCLUSION

Draft UUT Calibration of the Pressure Transmitters

Better accuracy has been observed while using Method 1, which is by setting up fixed Units Under Test (UUT) while the Master Standard Units (MSU) were changed until targeted UUT is reached.

Hysteresis

There were only slight differences comparing the increase and decrease trend. The value of hysteresis obtained is very small due to the well maintenance of the equipment.

Five Point Calibration of Pressure Transmitter

It can be concluded that the equipment are accurate. The errors are so small that they are within the tolerance range.