The Fieldpiece SCM4 is a standalone carbon monoxide detector (CO detector) with a very fast reaction time. Its 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 SCM4 standalone carbon monoxide detector 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.
How Does it Work?
Doing the "Walk-Around" Test: The SCM4 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
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 SCM4 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 gives you the other measurements you need to tune combustion equipment.
Features and Benefits
The SCM4 Carbon Monoxide Detector (CO Detector) offers several features and benefits to field technicians:
- Fast electrochemical sensor helps you find CO sources like
- cracked heat exchangers or breached flue stacks.
- Calibrate to ambient quickly with ZERO button.
- Audio and visual alarms (with MUTE function).
- Alarm rate increases as carbon monoxide concentration increases.
- MAX hold to help you zero in on the source.
- Bright-blue backlit dual-display to test in dark crawl spaces.
- Magnetic hanger for hands free testing.
- 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.
We've included our carbon monoxide specific, electrochemical sensor in our carbon monoxide accessory head (model ACM3) for years now. The SCM4 uses the same electrochemical sensor. We haven't found a sensor on the market that outperforms our sensor.
Besides the advantages outlined above in Features and Benefits, the SCM4 adds various other benefits, such as:
- 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.
- Loud audible alarm that beeps faster as CO concentration increases.
- Rugged sensor maintains accuracy over time.
- Ruggedized body and rubber boot stands up to abuse many competitive models cannot.
- Optional AOXP2 hand pump works much better in cold weather than most electronic pumps.
- Carbon Monoxide Detector - SCM4
- 9V battery (installed)
- Operator’s manual