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The 402AS Automatic Sequencer allows a single Nova gas analyzer to be time shared between 3 to 24 sampling points. This greatly reduces the cost per sampling point for multiple-zone analyses.
The 402AS consists of microprocessor based timing, a solenoid valve for each point and a by-pass pump. The by-pass pump continuously draws on all sample points so as to keep fresh sample always available for analysis. Unwanted sample points can simply be skipped over. Also, the timer can be stopped on any one point and held there for as long as desired with a simple key press. A small keypad allows easy data entry.
If purchasing Model 402AS, please specify method of sample stream identification : 5V TTL, contact closure, or RS-485 output.
Unit of Measure

Method of Detection

N/A No detection; sequences sample streams to (separately sold) analyzer for detection

Ranges Available

N/A Any between 3-24 samples

Ambient Temperature Range

N/A 32 to 122°F (0 to 50°C), Lower temperatures (-5°F, -20°C) with Cold Weather Package

Size & Weight

N/A Dimensions will vary depending on enclosure style, number of sample points and options and required


N/A 115 VAC, 60 Hz 220 VAC, 50 Hz

Output Options

N/A 5V TTL, RS-485, or contact closure

Industry Type

N/A Agriculture Online Process Analysis


    Allows a single Nova gas analyzer to be time shared over many sample points. It can be controlled locally or remotely. Applications include multiple greenhouses, mushroom farms, multiple flue gas ducts, multiple landfill well or area sampling.


  • Available from 3 to 24 sample points selected by solenoid valves
  • Greatly reduces cost per sample point for multiple-zone analysis
  • Digital display of active sample point with time remaining countdown
  • Selectable sample time
  • Provides sample stream identification
  • Manual override with sample hold
  • Skip feature allows unwanted samples to be skipped over.
  • All samples continuously drawn into sequencer by built in pump to keep non-active samples 'fresh'
  • Only active sample point goes to analyzer, the rest are vented.


  • Stainless steel in place of flexible tubing for use with PPM or other low range analyzers
  • Microprocessor controlled by customer or PLC or locally by Nova supplied built in controller
  • RS-232 or RS-485 output
  • Relay contacts for each sample point
  • Solenoid valves in 401S are available in 6V, 12V, 24V, and 24VAC/115VAC versions.

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