Hach One Process Ph Electrode; Sodium Error; Hach One Orp Electrode - Hach EC1000 Instruction Manual

Process ph/orp system

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1.4 Hach One Process pH Electrode

Figure 3

Sodium Ion Error Graph

The Hach One pH Electrode features a continuous, free-flowing reference junction to

assure a constant long-lasting reference potential. The electrode contains a replaceable

pH glass sensor (in bulb or flat configuration) a reference half cell, a temperature sensor,

and an internal preamp. The internal preamp produces two current loop signals, one for

mV and the other for temperature. The preamp allows for up to 1000 feet of separation

between the electrode and meter, and is operable up to a depth of 40 feet. The

electrode housing works in any of the sample handling systems described in Section 1.7

Sample Handling System.

Acid error is negligible; negative sodium error, usually present in alkaline solutions, is low

even at pH values as high as 12. To determine the sodium error in pH units, measure the

apparent pH and sodium concentration of the test solution and determine the error from

Figure 3. Locate the point (on the appropriate pH horizontal grid line) representing the

sodium concentration based on the extrapolation between the 229, 2,290, and

22,900 = mg/L Na plots. Add the vertical grid line at that point to the apparent pH meter

reading. For example, a sample that reads pH 12 with a Na+ concentration of 0.5M has a

negative sodium error of approximately 0.12 pH units. Therefore, the actual pH of the

sample is 12.12.

The Hach One ORP Electrode also features the continuous, free-flowing reference

junction, a temperature sensor, and a preamp. It is housed in the same electrode body as

the pH flat configured electrode (see Figure 4 on page 22). The replaceable sensor is a

Platinum disc sealed in glass. Select the mV readout for ORP applications.

TYPICAL SODIUM ERROR FOR

HACH ONE COMBINATION pH

ELECTRODE (AT 25 °C)

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