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PMI Dilution Probe

PMI Dilution Probe

PMI Dilution Probe for in-situ sampling conditioning of stack gases.

The Dilution Probe performs four critical functions to prepare the sample from the stack or process, so it can be measured accurately and precisely by the analyzer. The probe uses an air-driven aspirator which extracts the sample from the stack or process. It is then passed consecutively through coarse and fine particulate filters, a pre-selected glass or metal critical orifice, and finally diluted with the air from the aspirator. This process has now reduced the dew point of the sample to below that of the ambient air, preparing the sample so that it can be transported via an unheated line to the analyzer up to 300 feet away.

SKU: PMI-❒ Category:


There are two models of the Dilution Probe available, differing only in the type of mounting flange. Model PMI-3200, equivalent to the EPM 0797.302, has a 1.8-inch flange drilled and tapped with four mounting holes. Model PMI-3300 (equivalent to EPM 0797.303) has a threaded flange for easy use with extension tubes.

PMI Dilution Probe Diagram


  • Low-cost installation, maintenance, and operation
  • Low-extractive flow rates, promotes long filter life
  • Made of corrosion-resistant materials
  • Can be used in explosion-proof areas
  • No requirement for a heated sample line
  • No moving parts anywhere in the system
  • Easy dynamic in-situ calibration of dilution system
  • Diluted sample is transported at positive pressures
  • Can be used with any existing ambient air analyzer
  • Manual or optional automatic blowback, back flushes coarse filter PMI-3000 probe


Material of construction:

  • The eductor housing, mantle, filter cap, and flange (the “Wetted Parts”) are fabricated from alloy 600, a corrosion-resistant nickel-chromium alloy
  • The heat exchanger and the four inlet/outlet tubes are fabricated from grade 316 stainless steel

Maximum operating temperature:

  • 750ºF (400ºC) with standard glass orifice
  • 1,100ºF (600ºC) with special metal orifice


  • Vacuum and calibration lines 0.125-inch outer diameter
  • Dilution air and sample out lines 0.25-inch outer diameter
  • All lines supplied with 0.25-inch outer diameter tube fitting attached


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