CNR4 Net Radiometer

The CNR4 Net Radiometer is designed to measure total radiation, which represents the balance between incoming and outgoing radiation in an outdoor environment.

The Net Radiometer CNR4 consists of a pair of pyranometers for measuring short-wave incident and reflected radiation and a pair of pyrgeometers for measuring long-wave infrared incident and reflected radiation. In addition, the sensor is equipped with a Pt100 temperature sensor for parallel recording of the sensor temperature.

Optionally, the sensor can be supplemented with a ventilation unit containing a heating resistor and a fan. The ventilation unit is used to remove water droplets condensing on the measuring sensors at high humidity.

Net radiometr CNR4 měření dlouhovlnné i krátkovlnné radiace

Measuring transducer

The CNR4 pyranometer can be connected directly to the TEP06 / P transmitter, which is compatible with all FIEDLER telemetry stations and data loggers equipped with the RS485 serial bus.

Měřící převodník a zesilovač k pyranometrům a pyrgeometrům CMP4

Diagram of connection of Net Radiometer CNR 4 to measuring transducer TEP06 / P

Adjustable sensor holder

A robust universal stainless steel holder DNR2 can also be ordered together with the device. The holder is designed for quick and stable installation of the Net radiometer CNR4 on a vertical mast. The holder is installed using stainless steel brackets T1.5 (mast with a diameter of 33 mm) to T2.5 (mast diameter 60 mm) and allows you to set the horizontal working position of the device in two planes.

DNR2 nerezový držák Net Radiometru CNR4

Difference between CNR4 and NR Lite2 radiometers

Both devices use thermocouples, but the dome above the thermocouple determines what type of radiation passes through and reaches the thermocouple. The thermocouple is usually protected by a single or double dome to reduce deviations caused by sudden temperature changes such as wind.

The CNR4 net radiometer uses two glass domes to cover the pyranometer and two silicon domes to cover the pyrgeometers. It uses two thermoelectric detectors (1 for each of the two pyranometers and 1 for each of the two pyrgeometers) and provides two separate outputs. One for short waves (solar spectrum having a bandwidth of 300 nm to 2800 nm) and one for long wave radiation (long wave infrared spectrum having a bandwidth from 4500 nm to 42000 nm). This leaves a gap between 2800 nm and 4500 nm. This is the so-called atmospheric window, into which very little radiation enters (see picture below).

The NR Lite2 net radiometer is not protected by domes and is in direct contact with weather conditions. Due to the wind, it can therefore cool much more significantly, which affects the accuracy of the measurement. The NR Lite2 does not use a glass or silicon cover but has two PTFE coated detectors and provides a single output for shortwave and longwave radiation. It uses one thermocouple to measure the entire spectrum of longwave infrared and solar radiation. The PTFE thermocouple cover transmits a band from 200 nm up to 100,000 nm.