The model ACM3 carbon monoxide accessory head enables most digital multimeters to measure low levels of carbon monoxide in parts per million (PPM). The ACM3 is a carbon monoxide detector (CO detector) accessory head for use with our modular instruments. It has a very fast reaction time thanks to an electrochemical sensor is specific to carbon monoxide (CO). This rugged instrument 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 ACM3 carbon monoxide detector measures CO in parts per million (ppm). Use it for walk-around tests to help pinpoint sources of CO indoors.
How Does it Work?
The "Walk-Around" Test: The ACM3 responds to changes in CO levels in real time. You 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 ppm | Effects |
| 9 ppm | Minimal. Max allowable concentration for eight hours (EPA and ASHRAE). |
| 35 ppm | Max for continuous exposure for one hour (EPA and ASHRAE). |
| 50 ppm | Max for eight hours (OSHA). |
| 100 ppm | Trips installed CO detectors. UL2034 specifies a max exposure of 100 min. |
| 200 ppm | In two to three hours: slight headache, tiredness, dizziness, nausea.
UL2034 specifies a max exposure of 35 min. |
| 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 forty five minutes: dizziness, nausea, and convulsions.
In two to three hours: death. |
| 1600 ppm | In one hour: death. |
| 6400 ppm | In fifteen minutes: death. |
| 12800 ppm | In three minutes: death. |
| Effect can vary significantly de[ending on age, sex, weight, and overall health. Never stay in an area of high concentration of CO, get outdoors and call emergency response. |
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:
- The flame must generate high concentrations of CO (lack of oxygen, excess fuel, high temp).
- Enough exhaust gases must be emitted from the heat exchanger crack.
- 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.
- 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 model 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.
Carbon monoxide concentrations will begin to show in two or three squeezes. For final reading, pump until the reading stabilizes, about 30 squeezes. Press MAX on SCM3 to hold the highest reading.
NOTE: To make an accurate assessment that combustion is within manufacturer's specifications, in addition to CO ppm, you also need to measure flue gas %O2 (%Oxygen), Temp, %CO2 (%Carbon Dioxide) and sometimes %EA (% Excess Air). The SOX2 Combustion Check Meter or AOX2 Combustion Check Accessory Head gives you the other measurements you need to tune combustion equipment.
Competitive Advantages.
Our proven carbon monoxide specific, electrochemical sensor continues to be a favorite of field technicians. It’s also found in our newer standalone CO Detector (model SCM3. We haven't found a sensor on the market that outperforms our sensor.
Besides the advantages outlined in Features and Benefits in the section above, the ACM3 offers additional advantages to field service technicians.
- Intuitive interface. A fancy way of saying easy to use. Technicians take it out of the box and know how to use it before even opening the manual.
- Rugged sensor maintains accuracy over time.(see Specifications below)
- Optional AOXP2 hand pump works much better in cold weather than most electronic pumps.