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MS-21 Pyrgeometer


Make: Delta ohm                                      Model: MS-21
✅ The MS-21 Pyrgeometer is a high-accuracy, robust infrared radiometer designed for measuring only longwave radiation with advanced features and traceable calibration, ensuring quality, accuracy and reliability with a 5-year warranty.
✅ Measurand: Longwave radiation
✅ Sensor Type: Thermopile
✅ Signal Output: Analog (mV)
✅ Supplied With: 10m meter cable, 5-year warranty & EKO quality guarantee, Factory test/ Calibration Certificates.

MS-21 Pyrgeometer:

The MS-21 Pyrgeometer is the ultimate solution for measuring longwave radiation. In meteorology, shortwave radiation is defined as wavelengths from 0.3 to about 4.5μm, while anything above that is classified as longwave radiation. The MS-21 is specifically designed to measure only longwave radiation of 4.5μm or more, thus eliminating any interference from solar shortwave radiation.

Featuring a specially coated silicon lens, the MS-21 can accurately measure longwave radiation even during the day, by effectively blocking out any unnecessary solar shortwave radiation. Additionally, the built-in Pt100 class A element ensures high accuracy in measuring the sensor temperature, allowing for thermal correction, further improving the measurement of received downward (upward) radiation.

To further enhance its performance, the MS-21 is equipped with an optional ventilation unit with a heater. This eliminates any undesired window heating offsets and mitigates issues such as dew, frost, and sensor soiling on the sensor.

Built with a new design concept focused on consistency and stability, the MS-21 minimizes temperature differences and suppresses window heating errors. It is research-grade, accurate, robust and delivers superior stability independent of the sensors’ operating temperature. Furthermore, it does not require a sun tracker with a shading device or shadow ring to measure longwave downwelling radiation and longwave net radiation in a wide spectral band.

The MS-21 is constructed with a silicon meniscus dome with a solar blind interference filter and hard carbon coating, a new thermal coupling design, onboard temperature-compensating electronics, and a unique aluminum alloy sun shield. These advanced features ensure that the MS-21 achieves the highest standards for quality, accuracy, and reliability. It comes with a 5-year warranty and is World Infrared Standard Group (WISG) traceable calibrated, using PT-100/4W IEC60751 Class A Industrial Platinum Resistance Thermometers and Temperature Sensors.

Application and features of MS-21 Pyrgeometer:



✅ Agricultural,
✅ Ecological
✅ Hydrological weather networks
✅ Renewable energy applications.
✅ NEW thermal coupling design, outstanding low thermal resistance
✅ WISG traceable calibration
✅ 4.5µm – 42µm flat spectral response
✅ Low temperature dependency, excellent stability
✅ Designed & built for ultra-low window heating
✅ 5-year warranty & EKO quality guarantee



MS-21 Pyrgeometer

Weight (Mass)



Voltage (mV)

Measuring Range

Net radiation measurement range : – 250 to 250 W/m²

Non Linearity

< 1 %

Temperature Response

< 1 % (-20° to +50°)

Field Of View


Operating Environment

-40° … +80°

Response Time

< 18 Sec (@95%)

Zero Offset B

< 1 W/m²


10 to 20uV/W/m²


100 to 200Ω

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