UHF-HFS-Series

Supported Applications

The Omega UHF-HFS Series comprises heat flux sensors designed to measure and quantify thermal energy per unit area moving through a surface. These differential-temperature thermopile devices are utilized for measuring heat transfer in HVAC systems, insulation analysis, refrigeration systems, building insulation R-value measurements, and soil testing.

Operating Conditions & Performance

The series operates across distinct temperature ranges depending on the specific model. The HFS-5 and HFS-6 sensors are rated for a temperature range of -50 °C to 120 °C, while the UHFS-09 sensor is specified for -20 °C to 150 °C. All three models share a heat flux measurement range of +/- 150 kW/m².

Response times vary by construction: approximately 0.6 seconds for the HFS-5 and UHFS-09, and approximately 0.9 seconds for the HFS-6. Response time is defined as the duration required for sensor output to reach 63% of its final value (one time constant). Each unit includes an integrated Type-T thermocouple for surface temperature measurement.

Configuration Options

The series offers three distinct configurations tailored to different sensing area requirements and environmental robustness needs:

• HFS-5: A flexible sensor with minimal thickness (approx. 360 microns) encapsulated in Kapton (polyimide). It features a total sensor dimension of W = 2.7 cm, H = 3.4 cm and a sensing area of 6.3 cm².
• HFS-6: A large-area sensor with metal encapsulation for robustness, utilizing Kapton (polyimide), Copper, and High Temperature Black Enamel Coating. It measures W = 9.1 cm, H = 10.0 cm overall with a sensing area of 74 cm².
• UHFS-09: An ultra-sensitive plate sensor featuring rigid, water-proof construction using Kapton (polyimide) and Epoxy. It measures W = 9.2 cm, H = 8.7 cm overall with a sensing area of 52 cm².

Sensor sensitivity is provided individually for each unit on its respective calibration certificate. Calibration procedures adhere to ASTM standard C1130. Electrical connections consist of leads for both thermocouple output voltage and heat flux output voltage, utilizing a 4-wire configuration (2 leads for heat flux: bright red and white; 2 leads for thermocouple: darker red constantan and blue copper).

Key Product Differences

The primary distinctions within the UHF-HFS Series lie in physical dimensions, encapsulation materials, sensitivity levels, and temperature limits. The HFS-5 is characterized by its flexibility and minimal thickness (approx. 360 microns) with a nominal sensitivity of approx. 14.0 mV/(W/cm²). The HFS-6 provides a larger sensing area (74 cm²) with metal encapsulation and a nominal sensitivity range of approx. 70 – 90 mV/(W/cm²).

The UHFS-09 differentiates itself as an ultra-sensitive plate sensor with rigid, water-proof construction, offering the highest nominal sensitivity at approx. 1500 mV/(W/cm²). Unlike other models in the series, the UHFS-09 does not experience temperature dependence.