The Dickson THDx is an 8-inch circular chart recorder engineered for continuous monitoring and archival of temperature, humidity, and dew point across critical environments. Microprocessor control and electronic sensing deliver precise, real-time data collection with dual-parameter digital display and user-selectable recording intervals of 24 hours, 7 days, or 31 days.
## Technical Specifications
**Temperature Measurement**
• Selectable ranges: -20 to +120°F (-20 to +50°C) or +40 to +110°F (+5 to +40°C)
• Accuracy: ±1.8°F (±1.0°C)
• Sensor: Thermistor with 2.5 minute average response time at 63% full scale
**Humidity Measurement**
• Range: 0 to 95% RH (non-condensing)
• Accuracy: ±2% RH (0–60% range), ±3% RH (60–95% range)
• Sensor: Monolithic IC humidity sensor or thin film capacitor
**Dew Point**
• Range: -22 to +122°F (-30 to +50°C)
• Accuracy: ±2°C (95–30% RH), ±4°C (30–10% RH), ±8°C (10–5% RH), ±49°C (5–0% RH)
**Display & Recording**
• 8 inch (20.3 cm) circular chart with selectable 24-hour, 7-day, or 31-day cycles
• LCD digital display: dual simultaneous parameter readout with 1°F (1°C) and 1% RH resolution
**Environmental**
• Operating: 32 to +122°F (0 to 50°C), 0 to 95% RH non-condensing
• Power: AC adapter (120 VAC recommended) with four “D” battery backup
## Key Features
• Audio/visual alarms with independently adjustable high/low setpoints
• Remote sensing capability; extension cords available in 10′, 50′, and 100′ lengths
• Switchable display units: °F/°C and RH/dew point
• Min/max data capture for trend analysis
• User calibration access for all measured variables
• Locking control keypad and door for secure operation
• Standard connector interface for remote probe connectivity
## Typical Applications
• Laboratory and clean room environmental monitoring
• HVAC system performance validation
• Manufacturing process control and compliance documentation
• Storage facility climate verification
