Balsbaugh 900-18M Automatic Temperature Compensation Meter Controller Series 900

Balsbaugh 900-18M Automatic Temperature Compensation Meter Controller Series 900

The Balsbaugh 900-18M is a benchtop resistivity meter controller from the Series 900 line, designed to measure water or solution resistivity in Megohm-CM with automatic temperature compensation referenced to 25°C. It uses an analog meter movement with two scales — 0 to 1.8 and 0 to 18 Megohm-CM — and includes adjustable set-point control with Below Setting and Above Setting alarm indicators. The unit requires a Balsbaugh 900-.01T conductivity cell (.01 cell constant) for operation; no probe is included with this listing.

Specifications & What's Included

• Manufacturer: Balsbaugh
• Model: 900-18M
• Series: Series 900
• Measurement: Resistivity in Megohm-CM at 25°C (automatic temperature compensation)
• Meter scales: 0–1.8 Megohm-CM (red) and 0–18 Megohm-CM (black), dual-range analog movement
• Display: Analog meter movement
• Function switch positions: RD, GR, BL, CHK, OFF
• Set-Point knob: adjustable 0–18, front-panel
• Alarm indicators: Below Setting and Above Setting (illuminated front-panel indicators)
• Probe/cell connector: circular multi-pin locking connector on rear panel
• Compatible cell: Balsbaugh 900-.01T (.01 cell constant) — required, not included
• Power: AC power cord with standard 3-prong plug (attached)
• Form factor: Benchtop
• Probe/cell: NOT included

Applications

The Balsbaugh Series 900 controllers are used to monitor and control the resistivity of ultrapure water and process fluids — a critical measurement in semiconductor fabrication, pharmaceutical water systems, power generation boiler feedwater monitoring, and laboratory deionized water systems. The 900-18M measures up to 18 Megohm-CM, covering the full range from moderately purified water up to near-theoretical ultrapure water (18.2 MΩ·cm). Automatic temperature compensation allows accurate readings across varying fluid temperatures without manual correction. These instruments typically function as both a display meter and a process controller, using the set-point and alarm outputs to trigger downstream equipment such as valves, pumps, or warning systems when resistivity falls outside acceptable limits. The Series 900 platform dates from the 1980s and was a widely used instrument in industrial and laboratory water purity applications of that era, and these units remain in service wherever legacy water treatment systems are still operating.