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Accurate Measurement without Vapor Interference

The versatile PA4000 photoacoustic infrared gas monitor from General Monitors provides precise, high-performance gas monitoring.


versatile PA4000 Photoacoustic Infrared Gas MonitorThe versatile PA4000 photoacoustic infrared gas monitor from General Monitors provides precise, high-performance gas monitoring. According to the company, the monitor:

  • Eliminates interference from water vapors and offers a reliable, low maintenance, cost-saving solution in situations where contaminants or interference preclude use of other measurement techniques.
  • Is designed with an advanced photoacoustic, infrared sensor to monitor a variety of gases including hydrocarbons, solvents, alcohols, CO2, CO and other dangerous gases. 
  • Is stable, highly selective to the gas of interest, and can operate for months with virtually no drift. 
  • Eliminates cross-sensitivity to water vapor — It features a proprietary sensing technique that determines the amount of water vapor in the sample and subtracts it from the gas reading (this technique allows the gas reading to be stable with no compromise to measurement sensitivity).
  • Features a range of 0 to 1000 ppm depending on the specific configuration, as well as accuracy to ± 2 ppm at 0 to100 ppm and ± 10 percent of reading from 100 to1000 ppm. 
  • Additionally features sensitivity of 2 ppm and resolution of 1 ppm, with specifications for other ranges dependent on application — for certain gases, it detects concentrations as low as 0.01 ppm.
  • Is easy to install, operate and maintain — most installations are as simple as mounting the instrument, connecting the sample line and powering the unit. 
  • In its most common configuration, the monitor draws gas samples via an internal pump, which enables the device to monitor areas that are hard to reach.
  • Can be used by delivering a pressurized sample to the unit — In case of blockage by a dirty end-of-line filter or clogged sample line, the instrument alerts operators by producing a fault.
  • Indicates gas concentrations and alarms — The direct reading display shows the actual gas value as well as any current alarms and diagnostic messages, and the gas monitor is factory pre-calibrated so that it arrives ready to detect a specific gas at a desired range.
  • Operates over a wide temperature range of 32° F to +122° F (0° C to +50° C) and has a storage temperature range of -67° F to +158° F (-55° C to +70° C); additionally, it has a temperature effect of ±0.3 percent per degree (°C) of reading and operates at a humidity range of 0 to 95 percent relative humidity, non-condensing.
  • Can be configured to monitor up to eight remote areas with standard features including a vacuum fluorescent display, audio alarm and four relays; and can be housed in general-purpose, explosion-proof or rack-mount enclosures. 
  • Offers standard 4-20 mA and 0-10 V outputs. 

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