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Model 275HD Heated Dilution Sample Probe

Model 275HD Heated Dilution Sample Probe

The Universal Analyzers 275HD Heated Dilution Gas Sample Probe provides accurate dilution of the gas sample stream of up to 1000:1 whether dilution is required because of compliance or safety.

The 275HD keeps the critical orifice and eductors outside the stack in a temperature controlled environment along with a heated filter. The critical orifice is ruby (twice the absolute hardness value as quartz) encased in a stainless steel housing and pre-filter. The critical orifice and eductors are isolated from the main filter element to prevent damage during maintenance and filter changes.

A fast loop eductor is used to improve response time through the probe tube before the critical orifice and the motive or sample eductor. The dilution air is pre-heated to avoid condensation. A vacuum port is provided in the eductor manifold to monitor eductor performance.
The 275HD dual accumulator tanks deliver high volume, high velocity blowback to clean the filter in high dust loading applications. The heated flow path and filter chamber is mounted on a removable sub-flange for easy maintenance and probe tube replacement without disturbing the entire enclosure. 


  • NEMA 4X Stainless Steel Enclosure
  • Out-of-Stack Critical Orifice and Eductor
  • Stainless Steel Protected Ruby Critical Orifice
  • No Tool Filter Replacement
  • Eductor-Driven Fast Loop
  • Sub-Flange Easy Maintenance
  • Up to 1000:1 Dilution Ratio
  • 3”, 4” or 6” 150# Mounting Flange
  • Aggressive Blowback


  • Coal Fired Power Plants
  • Pulp and Paper
  • Waste Incinerators
  • Process Gas Safety

Technical Specifications

  • Dimensions: 19”H x 17”W x 15”D (483mm X 432mm X 381mm)
  • Weight: 85 lbs (38.6 Kg)
  • Mounting Flange: 3” 150#, 4” 150# or 6” 150# ANSI
  • Power: 400W, 120 or 240VAC
  • Area Classification: General Purpose
  • Temperature Control Sensor: PT100 RTD or Type J T/C or Type K T/C
  • Maximum Maintain Temperature: 600°F (315°C)*
  • Filter: 2µ Stainless Steel
  • Dilution Ratio: 8:1 to 600:1
  • Critical Orifice: Ruby (factory sized)
  • Dilution Air: Oil Free, CO2 Free, Particulate Free (< 0.1µ), -40C Dew Point 0.53 scfm @ 85 psig (15 l/m @ 5.9 Bar)
  • Process Pressure/Vacuum: 1.5 psig / 2.7 in H2O (103 mBar / 5 mm Hg)
  • Flow Path Material: 316 Stainless Steel & Viton
  • Enclosure: NEMA 4X, 304 Stainless Steel
  • Probe Tube: See Probe Tube Order Matrix: Heated/Unheated, 316SS/Hastelloy/Inconel
  • Tubing Connections: Diluted Process: 3/8” OD
  • Optional Undiluted Process: 3/8” OD
  • Dilution Air Supply: 1/4” OD
  • Blow Back Air Supply: 1/4” OD
  • Calibration Gas: 1/4” OD
  • Eductor Vacuum: 1/4” OD
  • Tubing Bundle Boot: 1.4” – 2.75” OD
*Higher temperatures available. Please consult factory.