The pHep®4 is a waterproof pH tester with a 0.1 pH resolution and an accuracy of +/- 0.1 pH. It has many advanced features that are found in more expensive portable instrumentation. One or two point calibration is automatic to two selectable buffer sets (4.01, 7.01 and 10.01 or 4.01, 6.86, and 9.18). To calibrate simply press and hold the left power/mode button for three seconds. Depending on buffer set chosen the button is let go once pH 7.01 or pH 6.86 is displayed. The meter is placed in the appropriate buffer. Once the buffer is recognized pH 4.01 will be displayed. For single point calibration the left power/mode button is pressed and the meter will escape to measurement mode. For two point calibration the meter is then placed in the second buffer. The meter will automatically detect the second buffer (i.e. pH 4.01 or pH 10.01). Once the second buffer is recognized the meter will automatically exit to measuring mode.

The pHep®4 also features a replaceable electrode with a stainless steel round connector. This cartridge design has no pins to line up or that can break. The HI73127 replacement pH electrode also features an extractable cloth junction. Every pH electrode has a junction. Many use a single ceramic frit which acts as a barrier between the inside reference cell to the outside sample. This barrier allows for a diffusion electrolyte that is necessary for the pH measurement. Any clogging of the junction will result in a reduced diffusion and as a result the readings will become erratic. Most probes will have to have this junction cleaned and if not possible then replaced. The extractable cloth junction of the HI73127 allows for the renewing of the junction. Simply extract ⅛” of the junction by pulling on the junction will expose a new portion. Any clogging that was present will be cleared and the response time will be back to normal extending the life of the pH electrode.