• 0 to 13 pH measuring range
  • Repeatability: ±0.05 pH
  • Non-flowing junction minimizes maintenance
  • Double junction reference cell provides longer life
  • Automatic temperature compensation
  • Wetted parts: ceramic, silicone and glass
  • Temperature/Pressure Rating:
    • 446 kPa abs at 130°C (50 psig at 266°F)
    • 584 kPa abs at 80°C (70 psig at 176°F)
    • 791 kPa abs at 40°C (100 psig at 104°F)


The Rosemount Analytical Model 328A Steam Sterilizable Sensor is specifically built for service in applications that require repeated steam sterilization up to 130°C (266°F).

The Model 328A Steam Sterilizable pH Sensor is the result of years of research and development, and an extensive field evaluation program, making it the most reliable, cost effective sensor of its kind.

The Model 328A's ceramic body and silicone rubber seals provide excellent chemical resistance to many organic compounds commonly found in food, beverage, and pharmaceutical applications. Several features have been incorporated to enable the sensor to typically withstand over 50 steam sterilization cycles.

The Model 328A's double junction reference cell resists the effects of electrode poisoning or fouling. Poisoning or fouling can occur when certain ions or substances such as chlorides, sulfides, and sugars are present that react with the Ag/AgCl element. The double junction reference further isolates the reference element from the process to extend the sensor's life.

A specially formulated, ultra-high viscosity KCl reference gel withstands degradation and significant change in viscosity in process temperatures as high as 130°C. The non-flowing junction eliminates the need for expensive and cumbersome pressurization hardware required in flowing type junctions.

The effects of aging of the pH sensitive glass membrane are slowed by the use of a special glass formulation. This formulation provides an expansion coefficient of the glass membrane that closely matches that of the internal glass body to virtually eliminate bulb cracking or breaking due to thermal shock.


This product can be used in the following applications: