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Owner's Manual

ProTech 8505 Battery Powered Commercial CO Monitor w/Digital Display and Memory

    Model 8505

  • Battery Powered
  • Digital LCD Readout
  • Display Backlight
  • Peak Level Memory
  • Peak Level Time Record
  • Electrochemical Sensor
  • Sensor Life Monitor
  • ACGIH, Cal/OSHA, NIOSH and OSHA Compliant
  • One Year Factory Warranty

The PRO-TECH 8505 Battery Powered Commercial Carbon Monoxide Monitor includes a continuous digital display, peak level memory, TWA readout, sensor life monitor, and smart backlight.

Carbon monoxide (CO) levels are sampled and recorded every second by an accurate and reliable electrochemical sensor. CO levels detected from 10 to 999 ppm are automatically displayed in the LCD readout. When a chronic carbon monoxide level of 20 ppm or more is detected, a flashing Red LED and 85db pulsating alarm are activated.

Pressing the reset button temporarily mutes the audible signal while the carbon monoxide level is rechecked. If the monitor continues to detect carbon monoxide levels of 20 ppm or more, the audible and visual alarm signals will reactivate automatically within 5 minutes. If carbon monoxide levels drop below 20 ppm, the alarm signals will not be reactivated.

The highest carbon monoxide level detected from 10 to 999 ppm, the duration of the peak level, how long ago the peak occurred, and the average CO level detected for the previous 8 hours can be displayed by pressing the memory button. An internal clock monitors the sensor life and activates visual and audible sensor expiration signals after two years.

The Pro-Tech 8505 Commercial Carbon Monoxide Monitor complies with ACGIH, Cal/OSHA, NIOSH and OSHA workplace exposure limits. Backed by a one year limited factory warranty.

Alternate CO monitor for commercial applications: Defender LL6070


  • Battery Powered: The ProTech 8505 Commercial CO Monitor includes a 9v alkaline battery.
  • Continuous Digital Display: CO levels detected between 10 to 999 ppm are continuously displayed in the alpha-numeric readout.
  • Peak Level Memory: Recalls from memory the highest CO level detected within last 30 days from 10 to 999 ppm.
  • Peak Level Time Record: The duration of the stored peak CO level, and how long ago it occurred, can be displayed by pressing the memory recall button.
  • Electrochemical Sensor: The electrochemical sensor is exceptionally reliable and accurate.
  • Sensor Life Monitor: Internal clock starts once battery is installed. Visual and audible signals notify you when sensor life has expired.
  • ACGIH, Cal/OSHA, NIOSH and OSHA Compliant: The ProTech 8505 complies with ACGIH, Cal/OSHA, NIOSH and OSHA workplace exposure limits.
  • One Year Warranty: The Pro-Tech 8505 Commercial CO Monitor is backed by a One Year Limited Factory Warranty.


  • Power Supply: 9vDC alkaline battery
  • Sensor: Electrochemical
  • Gas Detected: CO
  • CO Sampling Cycle: Every second
  • Digital Display: LCD alpha-numeric CO readout
  • Display Resolution: 1ppm
  • Accuracy: +/- 5% or 5ppm, whichever is greater*
  • Current CO Reading: Continuously displays current CO detected from 10-999ppm
  • Peak Level Memory: Displays highest CO level detected within last 30 days from 10-999ppm
  • Peak Level Time Record: Displays duration of peak CO level, and how long ago occurred
  • Time Weighted Average (TWA): Displays average CO concentration for prior 8 hours
  • Life Monitor: Sensor expiration signal after two years
  • Display Backlight: Alarm, memory and testing
  • Power Signal: Flashing Green LED
  • Audible Signal: 85db @ 10ft
  • TLV Alarm Level/Time: 20ppm within 7 hours TWA
  • REL Alarm Level/Time: 30ppm within 3 hours TWA
  • PEL Alarm Level/Time: 45ppm within 90 minutes TWA
  • STEL Alarm Level/Time: 190ppm within 5 minutes TWA
  • Alarm Visual Signal: Flashing Red LED
  • Alarm Audible Signal: 4 beeps every 5 seconds
  • Mute Button: Silences audible signal up to 5 minutes
  • Low Battery Visual Signal: Flashing Green LED
  • Low Battery Audible Signal: 1 beep per minute
  • Malfunction Visual Signal: Flashing Red LED
  • Malfunction Audible Signal: 2 beeps per minute
  • Sensor Expiration Signal: Displays End, flashing Green LED, 1 beep per minute
  • Test Function: Self diagnostic circuitry and manual test
  • Operating Temperature: 40-100 deg F at 10-90% RH
  • Case Color: White
  • Case Size: 5-9/16" x 3-7/16" x 1-5/16"
  • Applicable Standards: ACGIH, Cal/OSHA, NIOSH and OSHA
  • Warranty: One Year Limited Factory Warranty

ORDERING INFORMATION - Please call (800) 221-4785 for a quotation

*Specifications subject to change without notice. Display accuracy is first year estimate only, and may also be affected by environmental conditions and other circumstances beyond manufacturer's control. This CO monitor is not listed to the residential UL 2034 standard, and is not designed for vehicles or unconditioned spaces. The monitor is intended for use in commercial conditioned space applications.

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