G3 Frost Point Generator

RH Systems G3 Frost Point Generator

Precision Frost Point Generation

The G3 is a low humidity generator that encapsulates essential tubing, pressure regulator, flow regulator, and saturator within a sealed vacuum chamber. Use of the vacuum chamber eliminates atmospheric water vapor permeation and the need for thermal insulation materials in and around thermally controlled components. Additionally, Stirling cryo-coolers (more accurately Free-Piston Stirling Coolers) are used to cool the saturator.

With these improvements over conventional designs, the G3 has better accuracy and performance at low humidity due to reduced permeation effects, improved thermal insulation and control, faster cool down characteristics, and better maintenance access.

Principle of Operation

A hybrid humidity generator combines the features of the NIST-proven two-pressure and two-temperature humidity generation principles. Utilizing these principles, a stream of gas at an elevated pressure is saturated with respect to the liquid or solid phase of water at a given saturation temperature. Here, saturation temperature is the major determining factor for the quantity of water vapor admixed with the carrier gas. Pressure within the saturator is the major determining factor for the carrier gas quantity of the mixture. Upon leaving the saturator, the humidified gas stream (consisting of the water vapor admixed with the carrier gas) is then expanded to a lower pressure and warmed to an alternate temperature at the point of use, such as a Device Under Test (DUT). Measurements of the pressure and temperature within the saturator, and the pressure and temperature following expansion (generally at the DUT), are then used to determine the resulting humidity content of the gas stream. Humidity is then accurately controlled by regulation of the temperature and pressure within the saturator.

Using the two-pressure technique, humidity is generated by fully saturating gas at a known temperature and pressure, then reducing the pressure to a lower value (typically ambient) at the same temperature. The humidity produced by this technique is determined solely from measurements of temperature and pressure and does not rely on measurement of the water vapor content.

Multiple flow-controlled outputs

The G3 offers up to 3 independent flow-controlled outputs. Each output can flow up to 5 liters/min, with a total combined flow up to 10 liters/min.

Ultra-low range capability

Based on the highly efficient dual cryo-cooling mechanism, the G3 is capable of generating ultra-low humidity, achieving humidity concentration below 1 PPB (Part Per Billion).


We reserve the right to change design or technical data without notice.


Generated Humidity Output:
Water Vapor Concentration Range <1 PPB … 12000 PPM
Frost/Dew Point Temperature Range -120 °C FP … +10 °C DP
Frost/Dew Point Temperature Stability ±0.05 °C
Frost/Dew Point Temperature Accuracy ±0.1 °C (FP >-80 °C)
Generated Flow Rate Output:
Gas Flow Rate Range, per output 1 to 3 outputs at 0 … 5 slpm each
Gas Flow Rate Range, total 0 … 10 slpm
Gas Flow Rate Accuracy ±0.2 slpm
Gas Flow Rate Stability ±0.1 slpm
Saturation Temperature Control Range -120 °C … +20 °C
Saturation Temperature Control Accuracy ±0.05 °C
Saturation Temperature Control Stability ±0.03 °C
Test Temperature Connections 2 external temperature connections
Measurement Accuracy ±0.05 °C
Probe Type Pt100, 4-wire
Saturation Pressure Control Range Near ambient to 1 MPa (150 psia)
Saturation Pressure Accuracy ±0.05% FS
Test Pressure Measurement Range 0.07 … 0.12 MPa (11 … 17 psia)
Test Temperature Connections 2 external temperature connections
Test Pressure Accuracy ±0.05% FS
Utility Requirements:
Gas supply 0.3 … 1MPa @ 10 slpm. Max pressure 3 MPa
Gas Type Dry air or nitrogen
Supply Voltage 100-240 VAC, 50/60 Hz, Single phase
Power Consumption 1.5kW
Operating temperature +15 °C …+40 °C
Storage temperature 0 °C …+50 °C
Humidity 10 …95 %RH, non-condensing
Weight and Dimensions:
Height 1.2m
Width 0.8m
Depth 0.8m
Shipping Weight 318 kg