Vaisala GMP251 Carbon Dioxide Probe

Overview

Vaisala GMP251 is an intelligent, standalone carbon dioxide probe for %-level measurements, built on Vaisala’s patented CARBOCAP infrared technology. The measurement range is 0 to 20 %CO2 and the performance is optimised at 5 %CO2, where accuracy is ±0.1 %CO2 at 25 °C and 1013 hPa. The probe is designed for demanding applications such as life science incubators, cold stores and fruit and vegetable transport, where stable and accurate CO2 control protects products and experiments over long periods.

Seven Star LLC supplies the Vaisala GMP251 to laboratories, food and agriculture operators and industrial users in Oman and the GCC, with engineering support in Muscat. The Vaisala GMP251 is part of the same Vaisala measurement family as the Vaisala HMT330 humidity and temperature transmitter, and it can share Indigo transmitters and Insight software with the company’s humidity probes, which simplifies spares and training.

CARBOCAP Measurement Principle

CARBOCAP is a non-dispersive infrared technique. Carbon dioxide absorbs infrared light at a specific wavelength, and the probe measures how much of the light is absorbed as gas passes through its optical path. A tunable Fabry-Perot interferometer alternately selects an absorption wavelength and a reference wavelength, so the measurement compensates for ageing of the light source and for contamination of the optics. In the GMP251, a new type of infrared source replaces the traditional incandescent bulb, which extends the lifetime of the probe.

Raw absorption is then corrected for the conditions that affect it. An internal temperature sensor compensates for ambient temperature, and the probe can also compensate for pressure, oxygen and humidity effects. With compensation, temperature dependence at 5 %CO2 from 0 to +50 °C is within ±0.05 %CO2, pressure dependence from 700 to 1100 hPa is within ±0.05 %CO2, and humidity dependence across 0 to 100 %RH is within ±0.7 percent of reading. The sensor head is heated while power is on, which prevents condensation and allows operation in near-saturated air.

Engineering Design of the Vaisala GMP251

The Vaisala GMP251 is a compact cylinder, 25 mm in diameter and 96 mm long, weighing 42 g, with a smooth PBT polymer housing that is easy to clean and an IP65 rating. A PTFE membrane filter with a PBT grid protects the optics. The surface tolerates temporary exposure to cleaning agents, including hydrogen peroxide at 2000 ppm non-condensing, alcohol-based agents such as ethanol and IPA, acetone and acetic acid. The probe operates from −40 to +60 °C and can tolerate occasional heat decontamination up to +90 °C for up to nine hours when fully installed in the heated environment with power on.

Connection is by an M12 five-pin male plug-in connector, which makes installation and replacement fast. Output options include analog current and voltage outputs and a digital RS-485 output with Modbus protocol. The GMP251 can be connected to Indigo series transmitters and the Indigo80 handheld indicator for extended output and configuration options, and to Insight PC software for field calibration and device analytics. A flow-through adapter for the Vaisala GMP251 with gas ports is available for remote sampling with a separate pump, with recommended flow of 0.1 to 0.8 l/min. Start-up takes less than 10 seconds and full specification is reached after four minutes.

Key Features

The Vaisala GMP251 stands out for stability and ease of use:

• Measurement range of 0 to 20 %CO2 with accuracy of ±0.1 %CO2 at 5 %CO2 and ±0.2 %CO2 over 0 to 8 %CO2.
• Excellent long-term stability of ±0.3 %CO2 per year over 0 to 8 %CO2, supported by a long-life infrared source.
• Heated sensor head prevents condensation, so the probe works reliably in humid incubators and cold stores.
• Compensation for temperature, pressure, oxygen and humidity corrects the readings for real operating conditions.
• Plug-in M12 connector and smooth, easy-to-clean housing allow fast installation and hygienic use.
• Chemical tolerance to hydrogen peroxide, alcohol-based cleaners and acetone suits cleaning protocols in life science facilities.
• Analog and digital outputs with Modbus connect to most controllers, and Indigo transmitters add displays and relays.
• Calibration certificate is included, and Insight PC software supports field calibration and diagnostics.

Industrial Applications

The manufacturer lists life science incubators, cold storage, fruit and vegetable transportation and all demanding applications that need stable %-level CO2 measurement. In the Gulf, the same capabilities support research laboratories and hospitals using CO2 incubators, controlled-atmosphere ripening and cold chain for fruit and vegetable imports through Muscat, Sohar and Salalah ports, greenhouse CO2 enrichment, fermentation monitoring and ventilation or process gas checks where CO2 levels are in the percent range.

Seven Star LLC helps buyers select the output option, cable and Indigo transmitter for each project, and can supply the flow-through adapter for remote sampling. Teams whose measurement tasks extend to industrial gas analysis may also review the AccuLase-GPA TDL H2S, CO2 and H2O analyzer and the Servomex Micro i.s. 5100 portable oxygen analyzer for process gas needs outside the %-level incubator domain. Ask for the Vaisala GMP251 datasheet to see the full compensation tables and dependence data.

Technical Specifications

Specifications of the Vaisala GMP251 below come from the manufacturer datasheet and apply at 25 °C and 1013 hPa unless stated.

Request a Quote for Vaisala GMP251

To request a quotation for the Vaisala GMP251, tell Seven Star LLC the output type, cable length, transmitter or logger and any flow-through adapter you need. We supply the Vaisala GMP251 with engineering support in Muscat and can share the Vaisala GMP251 datasheet and calibration certificate details with engineering and procurement teams across Oman and the GCC.