Industrial HVAC systems — air handling units (AHUs), chillers, cooling towers, fan coil units, and VAV boxes — require precision pressure and temperature measurement for energy efficiency, air quality compliance, and predictive maintenance. Unlike automotive applications, industrial sensors must communicate with BMS (Building Management Systems) via standard protocols and survive continuous operation over 20+ year building lifetimes. Browse all application guides.
Differential Pressure Sensing: AHU Airflow Measurement
Flow-Pressure Relationship
Q = Cd × A × √(2 × ΔP / ρ)
Where Cd = discharge coefficient (0.6–0.98), A = cross-sectional area (m²), ρ = air density (kg/m³).
| Parameter | Typical Value / Range |
|---|---|
| Differential pressure range | 0–25 Pa (room), 0–500 Pa (duct), 0–2000 Pa (fan ΔP) |
| Accuracy | ±1.0% FS (or ±0.5 Pa for low-range room applications) |
| Output signals | 4–20 mA, 0–10V DC, Modbus RTU, BACnet MS/TP |
| Operating temperature | -10°C to +60°C ambient |
| IP rating | IP65 (outdoor AHU) to IP54 (indoor plantroom) |
| Response time | <1 s for averaging; <100 ms for VAV actuator feedback |
| Power supply | 24V AC/DC or PoE for digital variants |
| Long-term stability | ±0.5% FS per year, recalibration every 2 years |
| Compliance | ASHRAE 90.1, EN 13779, CIBSE TM65 |
Filter Monitoring via Differential Pressure
A DP sensor across the filter bank triggers replacement at set thresholds — typically 150–250 Pa for medium-efficiency, 600 Pa for HEPA. This prevents:
- Fan motor overload from increased system resistance
- Airflow reduction below minimum ventilation requirements (EN 15251, ASHRAE 62.1)
- Particle bypass through over-loaded filter media
BMS Protocol Integration
| Protocol | Standard | Max Distance | Max Devices | Best For |
|---|---|---|---|---|
| Modbus RTU | EIA-485 | 1200 m | 247 | Simple DP/temp sensors |
| BACnet MS/TP | ASHRAE 135 | 1200 m | 128 | BACnet BMS integration |
| HART | IEC 62591 | 3000 m | 63 | Multi-drop, legacy systems |
| IO-Link | IEC 61131-9 | 20 m | 1 (point-to-point) | Smart sensors, diagnostics |
| BACnet/IP | ASHRAE 135 | Ethernet | Unlimited | Large building networks |
Chiller Pressure Monitoring
Water-cooled chillers require pressure measurement at condenser (0–16 bar) and evaporator (0–12 bar) to detect fouling. Sensors must be compatible with:
- Glycol solutions up to 40% ethylene glycol
- Inhibited water at pH 8.0–10.5
- Biocides (isothiazolinone, glutaraldehyde) used in cooling tower water treatment
Industrial HVAC Sensor Solutions
Contact our engineering team for BMS-compatible pressure and temperature sensor specifications.