OM-141 Portable Temperature/Humidity Data Loggers w/USB Interface

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).