Start Up And Calibrate - Emerson Rosemount 3500P Quick Start Manual

Quick Start Guide
2

Start up and calibrate

2.1 Prepare electrode
Procedure
1. Remove electrode from shipping container.
2. Remove the protective boot covering the electrode bulb.
3. Rinse away salt film with clean water; then shake the electrode so
that the internal solution fills the bulb, thus removing any air trapped
there.
2.2 Calibrate with two point pH buffer solution
Select two stable buffer solutions, preferably pH 4.0 and pH 7.0. You can use
buffers other than pH 4.0 and pH 7.0 as long as the pH values are least two
pH units apart.
Note
A pH 7 buffer solution reads an mV value of approximately zero, and pH
buffers read approximately ±59.1 mV for each pH unit above or below pH 7.
Check the pH buffer manufacturer specifications for milivolt values at
various temperatures, since temperature may affect the actual value of the
pH buffer solution mV/pH value.
Procedure
1. Immerse the sensor in buffer solution.
Make sure the buffer solution contacts the metal housing of the
sensor, which acts as the solution ground contact.
2. Allow sensor to equilibrate to the buffer temperature and wait for the
reading to stabilize.
The transmitter can now acknowledge the value of the buffer.
3. Rinse the buffer solution off of the sensor with distilled or deionized
water.
4. Repeat steps
The theoretical slope value, according to the Nernst equation for calculating
pH, is approximately 59.17 mV/pH. Over time the sensor will age, both in
the process and in storage, and this will result in reduced slope values. To
ensure accurate readings, Emerson recommends replacing the electrode
when the slope value falls below 47 to 49 mV/pH.
2.3 Standardize pH sensor
For maximum accuracy, you can standardize the sensor in-line or with a
process grab sample after performing a buffer calibration and conditioning
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Step 1 through Step 3 using the second buffer solution.
Emerson.com/Rosemount
November 2020