The 491M gas standards generator provides:

  • Industry-standard for over 20 years
  • Permeation tube oven with wide temperature range controlled to 0.1 °C
  • Primary dilution mass flow rate
  • Standby, zero and span modes
  • Single-oven module can create mixtures with up to 8 components
  • Expandable

The 491M is ideally suited for creating trace concentration - ppm, ppb, and pptr - mixtures. The 491M uses KIN-TEK Trace Source disposablerefillable and diffusion permeation tubes for over 500 chemicals.


The 491M is composed of one or more of the following manually-operated modules, depending on application requirements:

  • 491MB Base Module (shown above): The "Base" module is required in every 491M instrument. This module provides manual front panel (a) oven temperature setpoint and primary dilution flow rate adjustment controls, (b) standby, zero and span selection, and (c) permeation tube oven temperature and primary dilution mass flow rate indication. Download brochure
  • 491M-PM Auxiliary Permeation Oven Module (PM): Additional permeation tube ovens allow generation of a multi-component gas stream for cases in which (a) the tubes must be maintained at different temperatures, (b) differing permeation technologies (disposable tubes vs. refillable tubes) are required, (c) more components are needed than can be held in a single oven, or (d) for applications in which various components will be switched in and out of the gas stream. Up to 5 PM oven modules can be added wherein each oven can hold up to eight disposable permeation tubes or one factory-refillable tube. Any combination of ovens can be kept on standby to keep various tubes at temperature while not adding their emission to the output gas stream. Download brochure
  • 491M-SD Secondary Dilution Module (SD): The SD Module extends the range of concentration attained from permeation tubes by providing an additional stage of dilution of the gas stream. Very low concentrations - ppb or ppt - can be generated depending on the emission rate of the tubes and the flow rate range of the primary and secondary dilution flow controllers. Overall dilution ratios of 10,000:1 can be achieved. Download brochure
  • 491M-GF Gas Feed Module (GF): Most applications can use liquid-filled permeation tubes. However, some compounds (e.g., NO, CO, O2, etc.) have very high vapor pressures and require a special mechanism to achieve desired concentration levels. The Gas Feed Module adapts an adjacent 491MB Base oven module or auxiliary 491-PM oven module and allows the customer to refill a "customer-refillable" gas-fed permeation tube. These are special tubes, typically made of stainless steel. Prior to shipment, KIN-TEK determines the tube membrane's certified emission rate for one or more components. In use, the customer typically supplies component gas from a cylinder to initially fill the tube and to periodically recharge it. Download brochure
  • 491M-DGB Direct Gas Blending Module (DGB): The DGB Module allows input of higher concentration component gas from a cylinder into the gas stream.The 491M gas standards generator then dilutes the mixture to produce a desired concentration. Dilutions from 1.5:1 to 200:1 are possible. Download brochure
  • 491M-HG Humidified Gas Module (HG): The Humidification Module allows addition of humidity to the gas stream. Up to 95% relative humidity can be added, depending on the overall dilution flow rate required to achieve the target concentration at the target relative humidity. Download brochure
  • 491M-IM Interface Module (IM): The Interface Module contains gas stream interfacing components needed to assure constant gas stream output conditions independent of variations in flow and pressure. The Interface Module is ideal for applications where flow capacity of end use is limited (e.g., filling of gas bags), or when back pressure is required to introduce the output gas stream sample to the device under test. Controls are provided on the front panel for adjusting the output pressure. Download brochure
  • 491M Modular Gas Standards Generator (shown below): The 491MB Base module and any additional modules can be packaged in stand-alone carrying cases or packaged in one or two 3-module expansion cases as shown below (unused module slots in the expansion case are filled with blank panels). Download brochure
The example 491M instrument above contains a 491MB Base Module, 491M-PM Auxiliary Permeation Oven Module and 491M-IM Interface Module.

491M features: 

  • Industry standard for over 20 years
  • Complete, integrated, ready-to-use turnkey system
  • Manually operated via front panel controls
  • Direct readout of oven temperature and mass flow rate
  • Modes of Operation: standby, zero and span
  • Designed for expandability 
  • Flow path designed for maximum flexibility with minimum error
  • Flow path suitable for reactive gases - mixture contacts only glass, Teflon® and stainless steel (other materials available) 
  • Optional component flow path materials available (sulfinert-coated, all stainless, etc.)
  • Accepts disposable permeation tubes, diffusion tubes, ultra-high rate liquid filled tubes, wafer tubes, and prefilled gas fed permeation tubes
  • Accepts up to 8 disposable tubes per oven with maximum 6 inch length x 1/4 inch diameter (KIN-TEK HRT, SRT and EL tubes)
  • Accepts one of KIN-TEK refillable LFH, ULED and 57 Series tubes per oven