Fieldpiece ACM3
Carbon Monoxide Detector Accessory Head
See: ACM4

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Fieldpiece ACM3 Shown
Product Information
Manual 741 KB PDF Datasheet
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  • Works with any Fieldpiece expandable instrument or handle or any DMM with mVDC ranges and our detachable leads
  • Fast electrochemical sensor helps you find CO sources like cracked heat exchangers or breached flue stacks
  • Calibrate to ambient quickly with ZERO calibration pot
  • Auto Power Off (APO) to save battery life (easy to disable)
  • Battery check with % of battery life left displayed
  • Use with optional AOXP2 pump for flue gas testing

The Fieldpiece ACM3 Carbon Monoxide Detector Accessory Head is a carbon monoxide detector (CO detector) for use with our modular instruments. The Fieldpiece ACM-3 has a very fast reaction time thanks to an electrochemical sensor is specific to carbon monoxide (CO). The rugged Fieldpiece ACM3 can help you hunt down sources of potentially life-threatening, poisonous gas.

Carbon monoxide (CO), a product of combustion, is an odorless, colorless gas. Faulty combustion equipment is one source of this dangerous gas known as the "silent killer". The Fieldpiece ACM3 Carbon Monoxide Detector Accessory Head measures CO in parts per million (ppm). Use it for walk-around tests to help pinpoint sources of CO indoors. Measure CO ppm in flue gas using the optional AOXP2 pump.


The Fieldpiece ACM3 Carbon Monoxide Detector Accessory Head responds to changes in CO levels in real time. The User must find the source of CO when levels rise on entry into a structure.

  • Zero the unit outdoors away from any source of CO
  • Enter the structure
  • Walk around and watch the display
  • Move toward the area of highest concentration to find the CO source

Persistent sources of CO, such as malfunctioning combustion equipment in occupied spaces, must be serviced immediately. The chart below outlines exposure guidelines as determined by various industry organizations:

CO Exposure Effects
CO ppm Effects
(effects can vary significantly depending on age, sex, weight, and overall health.
stay in an area of high concentration of CO; Get outdoors and call emergency Response)
9 ppm Minimal. Max Allowable Concentration for eight hours (EPA and ADHRAE)
35 ppm MAX for continuous exposure for one hour (EPA and ASHRAE)
50 ppm Max for eight hour (OSHA)
100 ppm Trips installed CO detectors. UL2034 specified a max exposure of 100 minutes
200 ppm In two to three hours: slight headache, tiredness, dizziness, nausea.
UL2034 specified a max exposure of 15 minutes
400 ppm In one or two hours: Frontal Headaches.
In three hours: Life threatening.
UL2034 specifies a max. exposure of 15 minutes
800 ppm In fourty five minutes: Dizziness, nausea, and convulsions
800 ppm In two to three hours: Death
1600 ppm In one hour: Death
6400 ppm In Fifteen minutes: Death
12800 ppm In Three minutes: Death

Testing for Cracked Heat Exchangers
A CO detector cannot tell you if a heat exchanger is good. A CO detector can indicate that a heat exchanger may be cracked only if all of the following conditions occur simultaneously:

  1. The flame must generate high concentrations of CO (lack of oxygen, excess fuel, high temp)
  2. Enough exhaust gases must be emitted from the heat exchanger crack
  3. The exhaust gases from the crack must not be diluted too much before coming in contact with the sensor. A cracked heat exchanger may leak CO in a small stream. You may measure high concentrations at one point but low concentrations only an inch away
  4. The heat exchanger must be the only possible source for the CO detected

The "Flue Test" and Remote Testing - Requires Optional AOXP2 flue gas pump
Too much carbon monoxide (CO) in flue gas is one indication to field technicians that combustion is incomplete. Use the Fieldpiece AOXP2 pump to extract samples from hard to reach places or from locations where the temperature is high (such as a flue). For potentially high concentrations of CO, pump slowly and stop if the measurement approaches 2000PPM.

Range 0 to 1000PPM (2000PPM with 5 minute max exposure time)
Initial accuracy at 73ºF±9ºF, >75%RH 0-15ppm ±5% reading ±1 ppm after zeroing
16-35ppm ±5% reading ±2 ppm after zeroing
36-1000ppm ±5% reading ±5ppm after zeroing
Display Updates real-time
CO air sample temperature range 32 to 105°F
Operating environment 32 to 122ºF (0 to 50°C)
Operating relative humidity 15 to 90%RH, non-condensing
Storage temperature -4ºF to 140ºF, 0 to 80% R.H. with battery removed from meter.
Sensor type Electrochemical (specific to CO)
Sensor calibration Factory calibrated on 205ppm
Long term drift <5% / year (depending on use)
Battery 9V
Battery life Approx.150 hrs typical (Alkaline)
Auto power off (APO) 15 minutes
Ordering Information
Model Description Buy Online Price
ACM3 Fieldpiece ACM3 Carbon Monoxide Detector Accessory Head Discontinued
See: ACM4
Included Accessories
  • 1 - Calibration screwdriver
  • 1 - 9-Volt battery (installed)
  • 1 - Operator’s manual
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