Honeywell UDA2182 manual Automatic Electrode Wash Setup, AutoCal Sequence and Piping

rinse/cleaning
solution	9782
	pH	to process
	electrode	S4
S1		to drain
process	Items outside this area
sample
	provided by user

Figure 15-11 Automatic Electrode Wash Setup

Select valves and fittings with appropriate pressure ratings

Make the process connections as shown in Figure 15-11. Be sure that valves and fittings (S1) have sufficient pressure ratings to withstand pressure peaks which will occur when process flow is blocked.

Minimize liquid volume in system

Keep pipe sizes small and couplings close to minimize the liquid volume in the system. Smaller volumes require less time to rinse.

15.17.1AutoCal Sequence and Piping

Introduction

AutoCal can include one-point calibration (standardization) to adjust zero to compensate for electrode drift, or two-point calibration (standardization and slope adjustment) to also adjust span to match the gain of the Analyzer/Controller to the electrode response.

Standardization and slope each depend on the electrode measuring a reference solution (buffer) of known pH.

Rinse and one-point calibration sequence

The AutoCal operation automatically occurs at the configured intervals. It always includes AutoClean rinsing of the pH electrode, in addition to any other AutoClean sequences that are configured to occur between standardization operations. The sequence is described below.

1All alarm action is held at existing levels. The output(s) can be held or be active, depending on configuration. Even if the outputs are not held, “HOLD ACTIVE” is displayed on the alarm stripe because alarms are always held.

Also, “AUTOSEQUENCE” is displayed. Pressing the DISPLAY key will call up a special display that shows how much time is left in the operation

2In preparation for the calibration, Relay 1 activates 3-way solenoid valve S1 (see Figure 15-12) to direct rinsing fluid to the electrodes for the configured rinse duration (1 to 1999 seconds). If the measured sample is normally returned to the process but quantities of rinsing fluid cannot be tolerated there, use an additional 3-way solenoid valve S4. It is activated simultaneously with S1 to

January 2009 UDA2182 Universal Dual Analyzer Product Manual 235