This machine is located in the chemistry lab which measures PH chemical dilutions.
 This device consists of an electrode.

The following description shows how the device works:

First, open the electrode cover and wash the electrode surface with distilled water and then put the electrode into buffer PH 7 standard. Wait till the device to be calibrated.

After that, wash it again with distilled water.

Then place samples below the electrode and immerse the electrode into the test delution, so that the dilution comes above the diaphragm.

Finally when the display is fixed, we read the shown number.