Conductivity Sampling Methods; Calibration Overview - Advantage Controls NANO XL Installation Maintenance Repair Manual

Conductivity Sampling Methods

A. Continuous - Typical for most tower applications. The controller is constantly reading the sensor
and activating the bleed relay based on readings relationship to the set point, set point direction and
differential. Example: A rising set point of 1500 and differential of 50 the bleed relay would activate
when the conductivity rises above 1500 and stays on until the reading drops to 1450.
B. Timed Sampling - A sample timer allows the conductivity to be sampled at periodic intervals.
Sample intervals are adjustable from 1 minute to 9 hours, 59 min. Sample duration (on-time) is
adjustable from 1 second to 99 minutes, 59 seconds. If the reading is below the set point by the
differential amount the bleed relay will be turned off at the end of the sample duration and the sample
interval countdown reinitiated. If the reading is above the set point at the end of the sample method
the bleed relay stays on until the reading drops by the differential amount.
C. Sample and Hold - Also uses a sample timer for periodic sampling intervals. The unit will sample for
its duration then hold the blowdown valve closed for a settable period (hold time). The conductivity is
checked at the end of the hold period, if additional blowdown is required the blowdown valve is held
open for a preset amount of time (blowdown time). Then sample cycle is repeated until the reading is
below the set point at the end of a hold cycle and the sample interval countdown reinitiated.
Note: Timed Sampling and Sample and Hold are typically used for boiler applications but Timed sampling
can also be used on small towers. On these tower applications the probe is installed in the bleed line
before the bleed valve.

Calibration Overview

The NanoTron controllers update the conductivity reading every two seconds with a running average. Nanotron
controller's conductivity scale should be selected so that the conductivity setpoint is as close as possible to
the middle of the scale. (See page 12 menu for setting scale).
Note: If a controller is using Timed Sampling or Sampling and Hold methods of control the conductivity
reading shown in the RUN mode may not be a current reading. The controller will hold and display
the conductivity value seen at the end of the last sample or hold duration. To see a current reading
force on the bleed relay with either the Force button or via the Calibration menu.
A. Continuous - Calibrating continuous sampling units can be done at any time with the probe in a steady
stream of water with no air or steam present.
B. Timed Sampling - While in the calibration menu there is a selection to force on the bleed relay. It
will force it into the sample period. After 1-2 minutes verify that the reading is stable then enter the
desired calibration value.
C. Sample and Hold - While in the calibration menu there is a selection to force on the bleed relay. It
will force the unit into its sample and hold periods and calibration should be done during the hold after
a fresh sample.
Notes:
1. If steam is flashing on boiler probes a stable reading will not be maintained and the controller will
not track.
2. Recalibration is required if the scale is changed in the Configure menu.
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