TDS Input Module
A new module has been designed to measure TDS within a steam boiler. TDS (Total Dissolved Solids) is the measurement of the amount of solids dissolved in water. The module actually measures conductivity of the water. The more solids that are in the water the more conductive it becomes.

TDS Function Block
A TDS function block has been created to convert the measured conductivity value, as measured by the TDS module in mS, to a temperature compensated TDS value in PPM(parts per million) or mS/cm@25oC. The block also allows a user to set a Probe Factor to cater for the relationship between the conductance measured with the probe and the specific conductance of the fluid. The TDS PV is then wired to a control loop that removes water from the boiler when it exceeds the loop setpoint. This method of control is referred to as Continuous Blowdown.

Timed Bottom Blowdown
This block has been designed to initiate a Timed Bottom Blowdown to remove the sediment that accumulates at the bottom of the boiler. It is normally carried out at least once per day. The 2704 block can cater for up to three blowdowns per day.

A high integrity network connection between controllers ensures only one boiler is blowing down at any one time. This is essential because the blowdown-receiving vessel will usually only be sized to cope with one boiler blowdown at a time