Spirax Sarco BC3250 is a multi-functional blowdown controller designed for steam boilers. It manages Total Dissolved Solids (TDS) by controlling the surface blowdown valve based on real-time conductivity measurements. Additionally, it features an integrated timer for bottom blowdown control to effectively remove precipitated solids from the boiler shell. The unit is equipped with a high-resolution LCD graphics display that provides clear process information via bar graphs and historical trend data, ensuring precise monitoring of boiler water quality.

System Functions and Monitoring

The controller continuously monitors conductivity through Spirax Sarco CP10, CP30, or CP32 probes. It includes an adjustable alarm and set point levels with a hysteresis function to prevent over-frequent valve operation in turbulent boiler conditions. For specialized requirements, it supports temperature compensation via a Pt100 sensor and provides a high-conductivity alarm to trigger a 'HI ALARM' state and de-energize the alarm relay.

Advanced Output Modes

• Continuous Output: Constant monitoring when the probe is mounted directly in the boiler.
• Purge Output: Used for pipeline-mounted probes to ensure a representative sample reaches the sensor at boiler temperature.
• Pulsed Output: Ideal for small boilers, opening for 10 seconds and closing for 20 seconds to prevent rapid water level drops.
• Retransmit: Isolated 0/4-20 mA output for remote TDS level display or integration with management systems.

Interface and Diagnostics

The graphics display is divided into three functional areas: large digits for the process variable, an information line for control states, and three bar graphs showing PV, Set Point, and Alarm levels. A dedicated trend graph screen records TDS variations over time.

Typical Applications

The BC3250 is suitable for standard Boiler Control Systems (BCS) and Condensation Contamination Detection (CCD) systems. In CCD applications, it monitors condensate return and redirects flow to the drain if conductivity increases above a preset level, protecting the boiler feed tank from contamination.

Maintenance Recommendation

Weekly maintenance should include taking a boiler water sample via a cooler to verify controller calibration and ensuring all isolation and blowdown valves operate freely.

Technical Data Summary

Feature	Specification
Power Supply	110V - 240V AC, 50/60Hz
Range	0 to 9.99, 99.9, 999, or 9990 ppm/µS/cm
Accuracy	±2.5% FSD
Relay Contacts	2 x SPCO, 3A @ 250 Vac (Resistive)
Comms	RS485 Modbus RTU, IrDA Infrared
Enclosure	Polycarbonate, IP65 (front panel)