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Model 728DCD Dilution Probe Controller

728DCD Dilution Probe Controller
A Model 728 Dilution Probe Controller is used in conjunction with a Dilution Probe to create a diluted sample. The dilution ratio can be increased or decreased by varying the dilution motive pressure with the dilution motive air regulator. The model 728 has a precision regulator with a double diaphragm to provide a stable dilution motive pressure to the dilution eductor located in the dilution probe for a stable dilution ratio. A gage is supplied that indicates the pressure of dilution motive air. In similar fashion the instrument air for the fast-loop and calibration gas each have a pressure regulator and a gauge. Solenoid valves are installed to cut-off the fast- loop and dilution motive air in the event of a low temperature alarm or if the filter needs to be changed.

The diluted sample returns from the dilution probe where flow meter(s) with needle valves are provided to distribute the diluted sample to the user’s analyzers. A flow indictor is provided for the sample bypass to prevent pressurization of the dilution eductor. A vacuum gage is included to monitor the dilution eductor. Calibration gases are manually and/or remotely controlled for calibrations and validations. The calibration gas status is shown with LED status indicators.

The Model 728 Dilution Probe Controller can be customized to meet your application with options for temperature monitoring and control, blowback, number of calibration valves and sample flow meters. Please consult the factory for any special requirements.



  • 19" Rack mount drawer with handles
  • Pressure and Vacuum gauges for monitoring
  • Precision pressure regulator for dilution air control
  • Flowmeters for sample and calibration gas
  • Calibration gas solenoid valves with manual/remote control
  • Temperature controller for heated filter/educator/orifice (optional)
  • Customizable with other features to meet specific requirements


  • Electric & Pneumatic control for a Dilution Probe
  • Provides Sample and Calibration Gas Flow Control
  • Provides Temperature Control to Dilution Probe Heated Filter/Orifice-Eductor

Operating Specifications

  • Dimensions: 10.5”H x 19”W x 21 3/8”D (267mm X 483mm X 543mm)
  • Weight: 25 lbs (11.3 Kg)
  • Power: 400W, 120 or 240VAC
  • Area Classification: General Purpose
  • Dilution Air Flow Rate Range: 5 to 15 l/m
  • Dilution Air Pressure Range: 20 to 80 psig (1.4 to 5.5 barg)
  • Dilution Air Dew Point: -40°F/°C
  • Operating Connections Provided:
    1. Dilution air inlet
    2. Dilution air to sample probe
    3. Diluted sample from sample probe
    4. Cal gas inlet (6 maximum)
    5. Sample/Cal gas outlet to analyzer bank
    6. Vacuum gauge line inlet to monitor
    7. Condition of eductor

Material Specifications

  • Chassis: Aluminum
  • Cal Gas Regulator: 316SS
  • Solenoid Valve Wetted Parts: 316SS with Viton O-Rings
  • Internal Tubing: PTFE Teflon