How accurate is the Inspector?
What is MAX Mode?
Why should I buy a pump?
Should the Inspector be mounted on the wall?
How does the Inspector differ from a CO detector from the hardware store?
I’m getting a ppm reading. What does it mean? What should I do?
How does the Inspector compare to other portable Carbon Monoxide detectors?
I am certain there is no carbon monoxide present. Why am I getting a ppm reading?
What is the difference between Carbon Dioxide (CO2) and Carbon Monoxide (CO)?
What does EOL (End of Life) mean?
Do I need to calibrate the device? How is this done?
How long does the battery last?
How much maintenance does the Inspector require?
What is TWA (Time Weighted Average)?
What does "intrinsically safe" mean?
Support/FAQ
How accurate is the Inspector?
Every Inspector is carefully calibrated before shipment. The LCD display has a resolution of 1ppm. Generally speaking the accuracy is +/-10%, (e.g. a reading of 100ppm will be displayed when the concentration reaching the sensors is 90-110ppm). At concentrations lower than 20ppm, the accuracy is +/-2ppm.
What is MAX Mode?
MAX mode allows you to calculate the maximum amount of potential gas exposure at any given time. This can be useful you wanted to see the maximum carbon monoxide level that you are exposed to through a vehicles exhaust. Another instance where MAX mode would be useful is if you were to sample the exhaust from your chimney. Max mode is perfect for this because the concentration will change when the air mixes with it. In order to use MAX mode, simply press the MAX button. If an arrow is over the word MAX this is an indication that MAX mode is active.
Why should I buy a pump?
While the inspector does not require use of a pump, a pump can be helpful if trying to draw a sample from a hard-to-reach area. Sensorcon sells both a Carbon Monoxide and Hydrogen Sulfide Inspector kit. The kit includes the Inspector device, a carrying case, and a hand aspirated pump. The pump allows the user to quickly draw an air sample, in order to quickly assess the gas concentration throughout a larger area.
Should the Inspector be mounted on the wall?
It is not recommended to mount the Inspector device on a wall, as the alarm is not as loud as traditional CO detectors. Ideally, the Inspector should be clipped onto your clothing or carried in your pocket for the most effective use.
How does the Inspector differ from a CO detector from the hardware store?
The inspector is a tool for measuring actual carbon monoxide concentrations above 35 ppm. A traditional hardware store CO detector is designed solely to sound an alarm when concentrations are elevated for extended periods of time.
| CO Concentration | Ul2034 CO Detectors | Sensorcon CO Inspector |
| 0-30ppm | Nothing happens from 0-30ppm. | Instant readout on LCD display in 1ppm increments. |
| 30-70ppm | Probably nothing At 30ppm+. Though there is a small chance that it will alarm but not for at least 30 days! Please consult the UL2034 standard which states that the device is not supposed to alarm for at least 30 days at 30ppm. This means it might not ever alarm until it's next threshold of 70ppm. | Instant readout on LCD display in 1ppm increments. LED and audible first alarm starts instantly at 35ppm+. This corresponds to the 8 hour time weighted average (TWA) set by the National Institute for Occupational Safety and Health (NIOSH) |
| 70-150ppm | At 70+ppm the alarm is supposed to start in 60-240 minutes. | Instant numerical readout and |
| 150-400ppm | At 150+ppm the alarm is supposed to start in 10-50 minutes. | Instant numerical readout, alarms active, higher alarm starts at 200ppm, which corresponds to the 15 minute ceiling set by NIOSH. Ceiling means this is the maximum workers should be exposed to for any period of time. |
| 400ppm+ | At 400+ppm the alarm is supposed to start in 4-15 minutes. | Instant numerical readout = high alarms active |
I’m getting a ppm reading. What does it mean? What should I do?
Concentrations less than 5 ppm shouldn’t be too concerning. Although it may be wise to keep an eye on it.
| ppm Reading | Possible Meaning | What you should do |
| 0-5 ppm | CO is normally present in the air at Electronics Noise (Our sensor is accurate to 2ppm) | Monitor it. Its normal to see small transients of 1-2ppm. If it stays in the 3-5ppm range then there may be a very small amount of CO present. Concentrations moving between O & 2 to 3ppm are typically sensor noise. This happens when the instrument is adjusting to a new ambient temperature. |
| 5-10 ppm | Indoors: There may be a small source of CO in the building. This is typically caused by a gas stove, cigarettes, an attached garage with an opening into the house or a furnace with improper venting. Outdoors: Most likely there is a local source of CO. This includes possibilities such as a campfire, grill or automobile exhaust. In urban environments, such concentrations may be encountered at busy intersections. | If you are indoors, then see if you can find elevated levels of CO by walking through the building with the CO Inspector. For faster evaluation you can use the hand aspirator pump to draw samples around you when as you walk. Keep in min to squeeze the bulb about once a second. Keep the Inspector in MAX mode to hold a high reading. If you are outdoors, then pay attention to what's going on around you and try to identify potential sources. See if lower concentrations are observed |
| 10-35 ppm | Indoors: These concentrations indicate that there is a local source of CO in the building. | These concentrations are higher than you should be exposed to over extended periods of time. Unless you are performing an exhaust test. If you can smell exhaust then you are not smelling CO (CO is odorless). You are smelling other gases such as NOx. However, vehicle exhaust has many toxic gases, including CO, NOx, some particulate matter and unburned hydrocarbon fuel. 10s of ppm CO is typical in a garage where a car was recently operating. If indoors, it is again most likely to be coming from combustion processes in the house like a stove, furnace, hot water heater, fireplace or cigarettes. |
| 35 ppm+ | Indoors: These concentrations are considered hazardous and are almost certainly coming from a large leak in | NIOSH specifies 35ppm as an 8-hr TWA limit. This meaning workers should not be exposed to this time weighted average concentration for more than 8 hours. If you are in an environment with such high levels then you should not stay in this environment for very long until the CO source is found and corrected. |
How does the Inspector compare to other portable Carbon Monoxide detectors?
The Inspector combines a rugged, compact, quality design with excellent ease of use at a low cost. There are three kinds of portable carbon monoxide detectors sold on the market today:
Diagnostic CO Detectors: These are usually fairly large devices sold by Bacharach, Fluke, UEI & others. In most cases they have poor battery life and are not water resistant. They are fairly easy to use and most have a MAX mode, require occasional calibration, and typically cost $200 to $400. Support for these products is virtually nonexistent and since the companies that sell them generally don't manufacture them. Sensorcon's carbon monoxide Inspector is made to the highest quality in the USA. It is rugged, water-resistant, has a standard battery that lasts for years and is fully supported by our knowledgeable staff.
Safety Carbon Monoxide Detectors: These are compact devices sold mainly by large gas detector companies for around $100 to $400. These companies are concerned with selling high volumes to large mining or industrial operations and they require frequent calibration. Sensorcon's carbon monoxide Inspector is just as small and robust as these safety oriented CO detectors. However, it is much easier to use. Sensorcon's support staff will answer any questions or concerns. We're not just making products for large companies. If you're a one man shop or just an average consumer that wants better information about carbon monoxide, we're here for you too.
Carbon Monoxide Analyzer: If you see the word "analyzer" it usually only means you will pay more. This being for the same technology and only a more fancy looking device. Maintenance issues are much higher. You can use our carbon monoxide Inspector for almost any application that you can use an analyzer for in measuring CO. As long as you are interested in ppm resolution over a 0-2,000 ppm range.
This frankly covers about 90% of the applications. Any analyzer in this range that uses an electrochemical sensor will not beat the Inspector's performance. If you are considering buying an expensive analyzer then please compare the specs to our carbon monoxide Inspector before you make your purchase. Feel free to contact us with any questions.
I am certain there is no carbon monoxide present. Why am I getting a ppm reading?
It is possible that an interfering gas or vapor is present. The most likely interfering gas is Hydrogen, with a 10-15% cross-sensitivity. This means that if the Inspector is exposed to 100ppm of Hydrogen, it will display a reading of 10-15ppm. Other gases, such as methane, will not prompt the Carbon Monoxide Inspector to respond. Alcohols should also not cause the Inspector to respond unless there is a significant amount near the gas sensor inlet. Cleaning the face of the Inspector with a small amount of alcohol should not cause the Inspector to respond. If you have any questions about the readings you are getting, please feel free to contact Sensorcon. We will do our best to help you figure out what is happening.
What is the difference between Carbon Dioxide (CO2) and Carbon Monoxide (CO)?
Carbon Dioxide (CO2) is NON-TOXIC, Carbon Monoxide (CO) is TOXIC. CO really wants to be CO2. If it can't find a 2nd oxygen to cling to, then it will try to cling to something else. If you breathe in carbon monoxide it will cling to the hemoglobin in your blood. Your hemoglobin normally likes to stick to oxygen too but can't with carbon monoxide around.
Therefore, carbon monoxide is toxic and it prevents your blood from clinging to oxygen. CO2 on the other hand, is what we exhale.
Both CO and CO2 can be formed by burning things: Whenever anything with carbon in it burns, it reacts to the oxygen from the air to form CO & CO2. Ideally only CO2 would be formed. In the real world, chemical reactions are never ideal. Burning is no exception. If any part of the fuel is burned with too little Oxygen, then it will form Carbon Monoxide (CO) rather than Carbon Dioxide (CO2). This is why the carbon monoxide Inspector is useful for so many applications including anywhere there is a flame and a chance for CO to be present.
What does EOL (End of Life) mean?
- EOL stands for End of Life, meaning the unit has reached the end of the electrochemical sensor's two-year expected life. This does not necessarily mean the sensor has failed, but two years is the average lifespan for this sensor type, so it is recommended to service the device for safe and accurate continued use, as we can no longer guarantee the functionality of the device past this point. If you have your own calibration kit, you can perform a calibration on the device, and if successful, the EOL message will clear, and the device can continue to be used safely for another 180 days. If you don't have your own kit, you can send it to us for service or order one if you prefer. Below are the options in more detail:
- You can send your device to us for a $49 calibration service. We will perform a calibration and, if successful, send your device back to you. This service also includes a new battery. If the one in your device is low or dead, we will replace it. If the battery is still good, we will toss the extra one in the box before we send it back to you. You can find the calibration service and all instructions here.
- If the device fails calibration, we can perform a full out-of-warranty refresh for an additional $20 ($69 total), which includes a brand-new calibrated sensor, a battery, and replacement of any other damaged/faulty parts. This also renews your 2-year warranty, essentially giving you a new device at a much lower cost as a benefit for being a current customer. We want our customers to stay safe without having to break the bank every few years. There is no limit to how many times this can be done, so in theory, you could hold onto the same device for over a decade! If you like, you can just order this service directly from our site. Instructions for the service and the order link can be found in the "Out of warranty" section.
- The calibration kit can be ordered directly from our site by clicking here. A 17L calibration bottle is good for ~20 calibrations, the 34L is good for ~40 calibrations, and the 116L is good for ~120 calibrations. These can also be used to regularly "bump test" the unit by applying gas for ~30 seconds and making sure the reading is within spec (45-55 PPM). We also offer a small 11L trigger bottle that can be used for tests, but not for calibrations.
Do I need to calibrate the device? How is this done?
When shipped, our meters are calibrated and tested to read within +/-10% of the calibration gas applied. Over time, all electrochemical sensors will drift, and we estimate our sensors to drift ~10% every 6 months. For the best accuracy, we recommend calibrating the sensor every 6 months. With this in mind, the user may choose to adopt a different calibration schedule.
The Average Property Owner: If you just want a rough idea of how much carbon monoxide is present around the house or you want to use the Inspector to find other CO sources, then the home owner may decide to not calibrate the sensor every six months. However, after two years, the sensor will read end of life (eol) and we recommend the homeowner send the sensor in for calibration.
General Purpose Professionals: If you are a professional Home Inspector, HVAC Technician, Fire Department, EMT, or in a related field, then we recommend calibration every 6 months to maintain the +/-10% accuracy specified. Please note that exposure to fluctuating temperatures and humidity can cause the sensor output to drift over time; therefore, we don't recommend storing the sensor in a vehicle or leaving the device outside when not in use.
Precision Professionals: If you demand the highest accuracy, (+/-10% or less) for applications like combustion analysis, energy audits, or medical applications then we recommend a calibration every 3 to 6 months.
Safety Applications: If you are planning to use the carbon monoxide Inspector for "mission critical" safety related applications, then you are obligated to follow standards set by OSHA or another agency. This will often require daily bump testing and monthly calibration.
How Calibration is Done: You can send your unit in to Sensorcon for calibration or do it yourself if you have calibration gas & a regulator with tubing. We offer calibration gas accessories on our web store.
If you'd prefer to do it yourself, follow the instructions below:
Inspector and Inspector Industrial units:
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Entering CAL mode
Press the POWER/MUTE and MAX buttons at the same time for 5 seconds to access the CAL screen.
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Performing the ZERO cal
In a clean air environment, press the MAX button to begin ZERO calibration. A 30 second countdown timer will be displayed while zero calibration is being done. Once complete, the sensor will beep, quickly flash CAL dn and then quickly flash the BASELINE value just before continuously displaying the word GAS. If you want to continue on with the GAS calibration, skip to step 3. If you only want to perform ZERO cal and not the gas calibration, press POWER/MUTE to exit. no CAL will flash on the screen before returning to normal operation. Note: ZERO cal in a non-clean environment will cause errors in the readings!
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Performing GAS cal
When ZERO cal is complete, use 1/4” OD, 1/8” ID Tygon tubing to attach the cal gas cylinder and regulator to the sensor inlet. Turn on the gas flow (rate of 0.3 to 0.5L/min). Press the MAX button to start the GAS cal process. A timer will countdown from 60 seconds for CO and 120 seconds for H2S. Once the countdown has finished, the sensor will beep, quickly flash CAL dn and then display the SENSITIVITY for 2 seconds before returning to normal operation. If there is an issue with the sensor calibration, the sensor will display err before returning to normal operation. If the sensor displayed err during calibration, please contact Sensorcon for further support. Note: Do not service this device in a hazardous environment.
Inspector Industrial Pro units:
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Entering CAL mode
Press the POWER/MUTE and MAX buttons at the same time for 5 seconds to access the advanced features series of menus. Press POWER/MUTE once to get to the CAL screen.
-
Performing the ZERO cal
In a clean air environment, press the MAX button to begin ZERO calibration. A 30 second countdown timer will be displayed while zero calibration is being done. Once complete, the sensor will beep, quickly flash CAL dn and then will show the BASELINE value. Pressing the MAX button will advance to the next screen displaying the word GAS. If you want to continue on with the GAS calibration, skip to step 3. If you only want to perform ZERO cal and not the gas calibration, press POWER/MUTE to exit. no CAL will flash on the screen before returning to the next advanced features series of menus. To return to normal operation, press POWER/MUTE two more times to exit. Note: ZERO cal in a non-clean environment will cause errors in the readings! -
Performing GAS cal
When ZERO cal is complete, use 1/4” OD, 1/8” ID Tygon tubing to attach the cal gas cylinder and regulator to the sensor inlet. Turn on the gas flow (rate of 0.3 to 0.5L/min). Press the MAX button to start the GAS cal process. A timer will countdown from 60 seconds for CO and 120 seconds for H2S. Once the countdown has finished, the sensor will beep, quickly flash CAL dn and then display the SENSITIVITY for 2 seconds before returning to normal operation. If there is an issue with the sensor calibration, the sensor will display err before returning to normal operation. If the sensor displayed err during calibration, please contact Sensorcon for further support. Note: Do not service this device in a hazardous environment
How long does the battery last?
Typically, the battery should last between 2-4 years. However, if the alarm is active on a regular basis, the battery can drain much quicker. The battery can be replaced with one standard CR123A Lithium battery.
How much maintenance does the Inspector require?
There is very little maintenance required for Inspector owners. The average consumer won’t have to do any maintenance. Professionals requiring a high degree of accuracy will simply need to perform occasional calibration. We also have service plans that eliminate downtime and maintenance for such professionals.
What is TWA (Time Weighted Average)?
Time Weighted Average (TWA) is an alarm standard used to measure exposure levels over an 8-hour period (the average shift length). Health and safety agencies set the TWA limit for carbon monoxide at 35 PPM, meaning that over an 8-hour period, if the unit is exposed to an average of 35 PPM or higher, the TWA alarm will alert the user. This is different from the low-level alarm of 35 PPM, which will alert the user immediately when the threshold is breached. The low level alarm is meant to inform the user of the presence of carbon monoxide so that they can make informed decisions, but does not represent an immediate health risk. At those low levels, prolonged exposure is what matters, and that's where the TWA is critical.
What does "intrinsically safe" mean?
Intrinsically safe means that a device has been certified as designed in such a way that no possible combination of failures within the unit could result in a spark with enough energy to ignite an explosive atmosphere. It is typically used in industrial applications where explosive gas atmospheres are possible, so certified equipment must be used.
More Questions?
If you have any further questions, please do not hesitate to contact us for more information.
E-Mail: sales@sensorcon.com
Hours of Operation:
Monday through Friday
8am to 4pm