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OM-140-Series
Portable Temperature/Humidity Data Loggers with USB Interface
Models In Stock
- One Button Starts/Stops Data Logging Without a PC
- Plug-and-Play USB 2.0 Interface No Need for Cables, Cradles or Docks
- Large Storage Capacity: 16,000 Pairs of Temperature and Humidity Readings
- 3½-Digit LCD Displays Real-Time Temperature and RH Readings, Device Working Status and “Memory Full” (OM-143 and OM-144 Only)
OM-140-Series
From
$
122.05
Models In Stock
Product Overview
- Battery life up to 1 yr
- Battery Size and Type 3.6V Li-ion
- Data Interface USB
- Field of view 2:1
- Form factor Handheld
- GPP Measurement 0 - 1500 GPP
- Height 23 mm
- Infrared Thermometer Emissivity 0.95 (fixed)
- Length 125 mm
- Measurement Type Humidity, Infrared, Temperature
- Operating Temperature, Max 70 °C
- Operating Temperature, Min -20 °C
- Relative Humidity Accuracy ± 3% RH
- Relative Humidity Accuracy Note ± 3% RH from 20 to 80% RH; ± 3.5% RH elsewhere
- Relative Humidity, Max 1
- Relative Humidity, Min 0%
- Relative Humidity Resolution 0.001
- Samples,Max 16000
- Samples Note 16,000 pairs of RH and temperature readings or 10,000 RH and temperature sets + IR readings
- Sampling Rate 10 Hz (10 updates/second)
- Sampling Rate Note Adjustable from 10 seconds to 12 hours
- Series ID OM-140-Series
- Supply Power Type Battery
- Temperature Accuracy ± 3.0 °C
- Temperature Accuracy Note ± 3.0°C for surface temperature measuremtn, ± 1 °C for ambiant temperature accuracy
- Temperature Measurement, Max 250 °C
- Temperature Measurement, Min -20 °C
- Temperature Resolution ± 0.1 °C
- Temperature Sensor Type IR
- Weight 200 g
- Width 43 mm
Supported Applications
The Omega OM-140 Series comprises portable, battery-powered data loggers designed for the unattended logging of ambient temperature and relative humidity (RH). These devices support applications requiring long-term monitoring over days, weeks, or months without a connected PC. The series calculates and displays absolute humidity metrics including Grains per Pound of Dry Air (GPP) in grains/lb or g/kg, dew point, wet bulb temperature, and mixing ratio. Specific use cases documented include water damage remediation where GPP serves as a moisture metric.
Operating Conditions & Performance
The series operates across an ambient temperature measurement range of -20 to 70°C (-4 to 158°F) and relative humidity from 0 to 100% RH. Accuracy specifications vary by model and operating band:
- Ambient Temperature: ±1.0°C (±1.8°F) from -10 to 40°C (14 to 104°F); ±2.0°C (±3.6°F) elsewhere in the range.
- Relative Humidity: ±3% RH from 20 to 80% RH; ±3.5% RH elsewhere.
The OM-144 model adds infrared surface temperature measurement with a range of -20 to 250°C (-4 to 482°F) and an accuracy of ±3.0°C (±4.0°F). Response times are documented as 5 to 30 seconds for ambient temperature, 8 seconds for relative humidity, and 0.5 seconds for the infrared thermometer on the OM-144.
Configuration Options
The series offers configurable features across three primary models: OM-141, OM-143, and OM-144. All units utilize a USB 2.0 plug-and-play interface for data transfer to a PC as .txt files and include software (ELusb V1.21.2) for graphing and exporting to Microsoft Excel or Word.
Model Configurations
- OM-141: Temperature/humidity data logger without an LCD display; includes a magnetic mounting base.
- OM-143: Includes an LCD display and magnetic mounting base for field viewing of readings.
- OM-144: Features an LCD display, built-in infrared thermometer with laser pointer (Class 2, 1 mW), fixed emissivity of 0.95, and a distance-to-spot ratio of 2:1.
Power & Storage
All models are powered by a single 3.6 V non-rechargeable lithium ion battery with typical life up to one year. Internal flash memory capacity supports up to 16,000 pairs of RH and temperature readings; the OM-144 can store 16,000 ambient pairs or alternatively 10,000 sets plus IR readings.
Key Product Differences
The primary distinction within the series is the presence of an LCD display and infrared capability. The OM-143 and OM-144 provide real-time visual feedback via their displays, whereas the OM-141 relies on status LEDs (HUM, TEMP) for indication without a screen.
Physical dimensions differ by model:
- OM-141: 31 W x 95 L x 28 mm D (1.22 x 3.74 x 1.10").
- OM-143: 32 W x 132 L x 28 mm D (1.26 x 5.19 x 1.11") with a weight of 200 g (7 oz).
- OM-144: 43 W x 125 L x 23 mm D (1.69 x 4.92 x 0.91").
The OM-144 requires an operating ambient temperature of 0 to 40°C (32 to 104°F) @ 10 to 90% RH specifically for infrared thermometer operation, while the general series operates within broader ranges. Accessories include protective USB caps, magnetic mounting bases (OM-141 and OM-143), USB extension cables, and replacement batteries (Part no. OM-EL-BATT).
PDFs & Manuals
Software & Drivers
Show Ratings & Reviews
Rated 5 out of
5
by
DR B from
So Far So Good
Been using two of these units for the past couple weeks and they are performing well. Temperature accuracy is as advertised (they give the exact same reading to the tenth of a degree C and these temps match other accurate devices I have. The relative humidity values vary by 0.5%, but this is in the advertised range. Very easy devices to set-up and to remove data..
Date published: 2016-12-26
Rated 4 out of
5
by
mccmfbgn from
Great value. Excellent product.
After 2 weeks of testing I'm going to give the OM-141 4 stars. If I could give it a 4.9 I would do that. I've only had one problem so far and it is not a showstopper.
I initially set the sampling rate to 30 seconds to collect and simulate a collection of many data-points, way more than we need), and in one week it had collected more data than the software seemed to download without a 'timeout' error being thrown. There needs to be a way to set the timeout value. When I put these in production we will set the sample rate to 12 hours, more than adequate for our needs, but I'd like to only download the data when I receive an alarm. if my freezers are doing well, I can foresee a timeout occurring if the time between downloads is sufficiently long to record a bunch of data-points.
In device setup, the sensitivity of the slider to set High/Low points is way too sensitive and I end up setting bounds slightly different from what I want. Not a big deal, but frustrating.
As I explore the software I am continually surprised by how many features are available. The best advice I can give to new users of the products is to "Read the **** manual".
Another problem we experienced had nothing to do with the device, but rather it was cockpit trouble: when we placed two of the device, I forgot to hit the start-button. I don't know what the solution would be on the OM141 to protect us from operator (me) error. Add that to your "would be a nice feature to have" list.
Date published: 2018-02-20
Rated 1 out of
5
by
Anyone from
Thermometer and RH with data log portable
It takes too long to changes in temperature. I regret purchase. Software to retrieve data is troublesome as well. I don’t recommend it.
Date published: 2023-07-27
Rated 3 out of
5
by
Lumidity from
OK for low budget
I wish I had purchased the 143. The 141 is hard to tell if it's Power On or Not.
Date published: 2018-09-08
Rated 1 out of
5
by
ThomasArnold from
Frequent software malfunctions
Purchased 4 of the base models of the OM-141. They worked the first time, well within advertised accuracy. Additional setups and data extraction work 10% of the time. Package software often has timeout errors even with small <100 data point sets. Frequently wipes data off devices for no reason as well. Manual and setup DVD provided no explanations for these peculiar cases
Date published: 2017-08-31
Rated 4 out of
5
by
power3153 from
great features
I bought this instrument a couple of weeks ago and its very helpful to monitor our
ac performance data.
Date published: 2017-07-23
Rated 5 out of
5
by
Rick W D from
Great out the box
Tested over and hour and checked. So far so good. Fixing to put them to work on mold lawsuit home and will follow up after recording for three weeks
Date published: 2017-07-19
The OM-140 series (141;142;143 and 144) are they suitable for the monitoring of ventilation temperature into the undergound mines ?
Thank you for your question. We will require more information to help on this question, please email the DAS team at DAS@OMEGA.COM
Date published: 2023-09-23
I use Linux, not Windows. A few Qs: 1. What is the default setting for sampling rate? 2. Will the device appear as a storage device if plugged into a Linux kernel? 3. If yes to 2., will the .txt data file appear on the device? Thx
Thanks for your questions. Unfortunately, the OM-141 (or the OM-HL-SP) will not support Linux since both logger’s software is designed for Windows. However, we can recommend the product OM-HL-SP, the max logging rate is 1 sec and the default is set to 60 secs. Please contact us anytime with further questions.
Date published: 2019-05-15
Regarding the OM-141 temperature/RH datalogger software, is it available for download as an alternative for laptop PCs without a CD drive?
Thank you for your question. ELUSB V2.04 software is available as a download from OM-141 product page. Just scroll down under manuals and downloads there will a software download.
Date published: 2022-09-22
I see the data sheet says these work with Windows® XP/7 or 8 operating system. Will these work with Windows 10?
At the time it is only tested to work with operating systems up to Windows 8
Date published: 2022-10-18
Is there a way to delete the data on the logger after it is no longer needed?
Thank you for your question. When you imitate a new configuration it will reset the logger and delete the memory.
Date published: 2025-10-29
Are these NIST calibrated, because the product details do not mention that. If not, what would be the cost of getting it calibrated?
Thank you for your question. The OM-141 is not available with Nist Please consider OM-EL-USB-2-PLUS which is available with Nist. I have attached 2 links from our website with details and pricing.
https://www.omega.com/en-us/temperature-measurement/temperature-and-humidity-data-loggers/om-el-usb-1-series/p/OM-EL-USB-2-PLUS
https://www.omega.com/en-us//p/OM-EL-USB-2-PLUS-NIST
Date published: 2023-02-08
Would this device be compatible with any type of probe . we are currently loooking for a device to measure compost temperature and humidity via some kind of probe. Thank you !
Hello Marc
As long as it is one of the following thermocouple types: J, K, T, E, R, S, B, C or N
Also the probe will need either a standard round prong or mini blade type connector attached at the end so it can connect to the transmitter.
Date published: 2019-08-28