Each model has different gas sensitivity. Please refer to the table below to choose the suitable model for your application.
| Model | Application | Targeted gases |
| OMX-SRM | Household odors, smell of lavatory/pet/wastewater disposal factory etc. | Ethanol, Acetone, Hydrogen, etc. |
| OMX-ADM | Smell from hospital/garbage/industrial oil/something putrid etc. | Ethanol, Acetone, Hydrogen, etc. |
| OMX-TDM | Place under construction, smell of painting/organic solvent etc. | TVOC（ex. Toluene), etc. |
OMX cannot identify and designate the types of gas. Please note that the devices basically detect compounded gas only.
It needs time for warming up to keep sensor sensitivity stable. Please refer to the table below for warming up. To measure odor more accurately, please attach air purifying unit and keep the device on for about 30minutes before use.
Time for warming up
- OMX-SRM…2min
- OMX-ADM…10min
- OMX-TDM…10min
There is no correlation between the indicated value by OMX and human sense of smell. Hence it is possible that the OMX may not show the strength value as you expected. This is because the human nose may have a high sensitivity to some low concentrated gases which OMX cannot detect.
On the contrary, OMX may show the strength value even though the human nose cannot detect any odor. This can occur when the OMX detects odorless gas or some other gases which are difficult for human nose to smell.
Do not use or store the device at the place where the following gases exist:
- Extremely concentrated odor
- Cigarette smoke and/or oil mist
- Silicon compound gas included in hair spray, adhesive, and silicon rubber etc.
- High concentrated chloride, acidic substances, corrosive gas, and chlorofluorocarbon etc.
- Water/steam/water vapor
The Handheld Odor Meter OMX is a simplified monitor to check odor strength collectively, it does not need calibration.
To make the strength value more accurate, we recommend zero-point adjustment instead of calibration for simplified measurement.
The OMX is not designed to be used for a long time, we recommend no more than ten minutes of continuous use. If it’s used for a long time continuously, it may effect inner components of the device which may cause failure.
OMX-SRM can be used for detecting the smell of a cigarette. However the ingrained cigarette smell in a room is usually low gas concentration and it’s difficult to detect by OMX in some cases even though human nose may detect it. Please prevent the OMX from directly suctioning cigarette smoke. If cigarette smoke goes into the sensor of OMX, it may cause failure. Please wait until the cigarette smoke completely falls to the floor, then carefully measure the odor so that the sensor does not suck cigarette smoke.
Please refer to the following instructions for setting up the zero-point adjustment:
- First of all, check the air purifying unit, suction nozzle or device itself to ensure clean condition. If the strength value does not decrease to zero with air purifying unit attached, it may have problem with the previously mentioned parts. Please refer to “A11″ for checking the device and suction nozzle condition, “A12″ for checking air purifying unit condition.
- Turn on the device in a clean air environment where odor or odorless gas do not exist. If there is no place under such condition, please attach air purifying unit and turn on the device for about 30 minutes.
If the strength value does not increase during measuring odor, the device interior may be contaminated or some odor factors may be in the device.
- To remove odor from inside of the device, turn on the device in a clean environment for ten minutes, or attach air purifying unit and turn on the device for ten minutes.
- The strength value may decrease if there are odor factors in suction nozzle or replacement filter. Replace the filter and dry the suction nozzle after washing it with water or alcohol solvent.
- If the condition does not recover after the step listed above and “A12″, there may be some other problems inside of the device.
Activated charcoal in air purifying unit could possibly become the odor factor if it’s been exposed to high concentrated gases for a long time. Please refer below for checking the condition of air purifying unit:
- Attach air purifying unit and turn on the device. If the strength value shows a higher value than the measuring result without air purifying unit, it’s better to replace the activated charcoal.
- If the strength value doesn’t decrease although the device is attached to the air purifying unit. In the case, it is better to replace the activated charcoal.
- If you smell strong odor by sniffing the activated charcoal directly, it needs to be replaced.
The OMX is not effected by temperature and humidity changes in normal living environment, however, it may not measure odor properly if there is change in measuring condition such as using the humidifier during the measurement. We suggest keeping the measuring condition consistent as much as possible.
Please refer to the following instructions:
- Prepare a gas bag which has outlet for suction nozzle or tube in. The bag needs to be sealed up and also needs enough capacity for sucking air for few minutes by the device.
- Inject a chosen amount of targeting gas in the bag, then dilute with a certain amount of clean air. Calculate the amount of targeting gas and clean air before injection.
- Keep the device clean by performing zero-point adjustment before the measurement.
- Put suction nozzle in and measure compounded gas in the bag. Wait until measuring value stabilizes before recording data.
- Remove the device from the gas bag, make sure the numeric value returns to zero point, then turn off the device.
- Prepare a gas bag.
- Inject the targeting gas into the gas bag.
- Set up zero-point adjustment.
- Put suction nozzle in a gas bag, start measuring odor. Wait until measuring value stabilizes, then record data.
There is no correlation between the indicated value of OMX-SRM and value of human sense of odor intensity, odor concentration or other odor index. OMX-SRM indicates relative value by comparing odor gas to purified air. This measurement is based on our original methodology. “Smell” is the information by human sense (sensitivity value), and there is no method that can accurately quantify various kinds of smells. There are some expressions such as “odor intensity” and “odor concentration” which are quantified based on human sense of smell. The OMX-SRM focuses on chemical substances contained in a smell and this device shows the relative strength of a smell numerically by using semiconductor gas sensors. The reading shown on display is calculated from the output from gas sensors using our original measurement to generate a numerical coefficient.
It is impossible to answer the first question from the perspective of the various points when measuring a compound smell. Even if device displays 300, you may perceive it as “an intense smell” or as “a week smell” depending on the kind of smell.
Smell has the following characteristics:
1. Smell is a gas consisting of multiple ingredients.
2. Smell has distinctive characteristics and there is no correlation with substance concentration and sensitivity value.
3. Also, they often impact to one another.
4. The human sense has a relation of being proportional to the logarithm of substance concentration.
Since semiconductor gas sensors react with substance concentration, it is difficult to acquire correlation with the reading from this device and sensitivity value according to the reason of above (2). For example, see the table below, it is considered that we feel smell of toluene faintly when it is 5ppm although we feel Isovaleric acid faintly when it is 0.00004ppm. Like these two substances, there is a significant difference between the kinds of substances and, therefore, it is impossible to get correlation between sensitivity value and substance concentration.
| Chemical | Slightly recognize there is odor | Slightly recognize the odor type | Detect odor easily | Strong odor | Very strong odor |
| Methylmercaptane | 0.0001ppm | 0.0007ppm | 0.004ppm | 0.03ppm | 0.02ppm |
| Hydrogen sulfide | 0.0005ppm | 0.006ppm | 0.06ppm | 0.7ppm | 8ppm |
| Trimethylamine | 0.0001ppm | 0.001ppm | 0.02ppm | 0.2ppm | 3ppm |
| Acetaldehyde | 0.002ppm | 0.01ppm | 0.1ppm | 1ppm | 10ppm |
| Isobutanol | 0.01ppm | 0.2ppm | 4ppm | 70ppm | 1000ppm |
| Xylene | 0.1ppm | 0.5ppm | 2ppm | 10ppm | 50ppm |
| Butyric acid | 0.00007ppm | 0.0004ppm | 0.002ppm | 0.02ppm | 0.09ppm |
| Toluene | 0.9ppm | 5ppm | 30ppm | 100ppm | 700ppm |
| Valeric acid | 0.00005ppm | 0.0004ppm | 0.004ppm | 0.03ppm | 0.3ppm |
It is a reference value for discrimination of different smells by using two gas sensors. Below table is sample value of each odor. This value indicates classification for single component of odor (gas). If figure is greater, it doesn’t mean that odor is stronger.
| Chemical | When material strength is… | Slightly recognize the odor type |
| O-xylene | Around 5.7ppm | Between 8 and 29 |
| Acetone | Around 110ppm | Between 30 and 54 |
| Valeric acid | Around 0.25ppm | Between 22 and 58 |
| Butyric acid | Around 0.27ppm | Between 36 and 60 |
| Propionic acid | Around 0.97ppm | Between 35 and 60 |
| Isovaleraldehyde | Around 0.18ppm | Between 35 and 63 |
| Ethanol | Around 100ppm | Between 41 and 67 |
| Acetaldehyde | Around 0.46ppm | Between 36 and 69 |
| Hydrogen sulfide | Around 0.21ppm | Between 36 and 78 |
| Methylmercaptane | Around 0.16ppm | Between 41 and 77 |
| Valeraldehyde | Around 0.62ppm | Between 41 and 66 |
*Above value includes a wide margin of error. Narrower value range will be indicated in actual measurement.
Please understand the main function of this device is that the relative strength of a smell can be shown numerically. This device can also provide you “Odor Classification” as second function and reference for discrimination of a smell by using two gas sensors the principle is uses the output value from two gas sensors that have distinctive characteristics and provide different output values.
When outputs from Sensor A and Sensor B are applied to vertical and a horizontal axis, figure shows degree of the “angle” between the peak of each output and the starting point. When you measure a pure single substance with this device in a chamber and get reading for each substance, you can make your own table, which is correlation table of a substance name and the discrimination reference value.
In case of compound smell, you cannot use the above-mentioned correlation table, for example when you find similar reading of hydrogen sulfide, you cannot consider that it is compound smell and main component is hydrogen sulfide. You cannot disregard chemical reaction of combined components and cannot consider it is compound smell of hydrogen sulfide mainly.
When measuring the effect of deodorization, or judging when a certain smell is removed, the discrimination reference value can be observed before deodorization. You will find intensity has fallen after deodorization, but discrimination reference value would be the same. If you deodorize by the adsorbing methods such as activated carbon, you can explain that the strength level is reduced without an unpleasant smell ingredient’s adsorbing uniformly and composition hardly changing.
There is a technique of masking which deodorizes with alcohol or fragrance. In this case, the perceived smell level falls dramatically but this is just, as you know, masking over the smell. Since this device also reacts to alcohol and fragrance, the intensity of the reading is possibly increased.
It’s used for measuring odor in various places such as factories, lavatories, hotels, garbage disposal plants, wastewater treatment plants and other places in daily life.
It detects relative change of odor collectively and shows numeric value according to the concentration of compounded gas.
It digitally displays the odor strength level according to the relative change in the odor being measured.
It’s suitable for check the effect of deodorization before and after deodorizing, checking the transition of odor strength, and finding the source of odor.
If it is requested to detect ammonia gas only, OMX-SRM is not suitable for this application. However there are cases that bad smell are resulted from several types of gases, not only ammonia, so for most of cases, we recommend OMX-SRM.
However if there are environments where ammonia exists, it’s most likely various kinds of malodorous components exist as well, OMX-SRM has a sufficient sensitivity for these gases, so it may use for managing the total odor level.
OMX-ADM has good sensitivity to ammonia, hydrogen sulfide, methyl mercaptan, it’s used for measuring pet odor and ammonia smell, detecting odor in hospitals and nursing homes, measuring garbage odor level in garbage disposal plants, restaurants and fish markets.
OMX-TDM is used for detecting TVOC in living environments, petrochemical factories and manufacturing plants for organic solvent products. It detects relative change of odor collectively and converts into numeric value according to the concentration of compounded gas. The main application is for detecting TVOC in living environment for health hazard prevention of residents such as sick house syndrome.
