| Product Identification | Manufacturer | Foxboro (now Schneider Electric) | |
| Model Number | RH924WA | "WA" suffix typically denotes Weatherproof Aluminum Case |
| Product Type | Single-Pen Circular Chart Recorder | Analog mechanical recorder |
| Series | Foxboro 900 Series Circular Chart Recorders | Includes RH918, RH924, RH938 variants |
| Recording Specifications | Chart Type | Circular Chart | |
| Chart Diameter | 250 mm (9.8 inches) | Standard size |
| Chart Rotation Speed | 24 hours (standard); Optional: 8h, 12h, 48h, 96h, 168h (7 days) | Driven by synchronous motor |
| Chart Drive | Spring-wound or Electric Motor | Electric motor standard on RH924WA |
| Pen System | Single Stylus Pen | |
| Span Adjustment | Manual via calibrated range screws | |
| Zero Adjustment | Manual | |
| Accuracy | ±0.25% of full scale (typical for voltage/mA inputs) | Depends on input type & range |
| Repeatability | ±0.1% of full scale | |
| Deadband | ≤0.1% of full scale | |
| Input Specifications | Input Signals | Universal: DC Voltage (mV, V), DC Current (mA), RTD, Thermocouple | Configurable via jumpers/switches & range card |
| Standard Ranges (Voltage) | e.g., 1mV, 5mV, 10mV, 50mV, 100mV, 1V, 5V, 10V | Requires appropriate Range Card |
| Standard Ranges (Current) | e.g., 10-50mA, 4-20mA, 0-20mA | |
| Thermocouple Types | B, E, J, K, R, S, T | |
| RTD Types | Pt100, Cu10, Cu50 | Typically 2-wire or 3-wire |
| Input Impedance | ≥1 MΩ (Voltage); ≤10Ω shunt (Current) | |
| Mechanical & Physical | Housing Material | Cast Aluminum (Weatherproof) | "WA" designation key feature |
| Protection Class (IP Rating) | NEMA 4X / IP66 | Weatherproof, dust-tight, corrosion-resistant; suitable for harsh
environments |
| Window Material | Tempered Glass or Polycarbonate | |
| Case Color | Typically Gray or Safety Yellow | |
| Dimensions (Ø x Depth) | ~305 mm Ø x ~180 mm (12" Ø x 7.1") | Excludes mounting hardware |
| Weight | ~9 kg (20 lbs) | Approximate |
| Mounting | Front-flange mounting (bolts through case rim) | Gasketed for seal |
| Environmental | Operating Temperature | -40°F to +140°F (-40°C to +60°C) | With chart installed |
| Storage Temperature | -40°F to +160°F (-40°C to +71°C) | |
| Humidity | 0-95% RH (non-condensing) | |
| Power Supply | Standard Voltage | 120V AC, 60Hz; 240V AC, 50Hz | Other voltages/configurations available (e.g., 24V DC) |
| Power Consumption | ~15 VA (typical for AC models) | |
| Fuse Rating | 0.5A Slo-Blo (120V); 0.25A Slo-Blo (240V) | |
| Accessories & Options | Charts | Paper, Plastic, Laminated; Various scales (linear %, °F/°C, psi,
etc.) | Pre-printed scales matching input range |
| Pens & Ink | Fiber-tip or pressure-sensitive; Replaceable ink cartridges | |
| Alarm Options | Optional: Electro-mechanical limit alarm with SPDT contacts | Adjustable setpoint, deadband |
| Transmitters | Optional internal signal conditioners (e.g., thermocouple to
4-20mA) | |
| Compliance & Standards | Certifications (Historical) | UL, CSA, FM (Class I, Div. 2 / Zone 2 hazardous areas) | Specific certifications depend on exact model/year |
| Sealing | Gasketed door, conduit entries with plugs | Maintains NEMA 4X/IP66 rating |
| Key Features | Robustness | Designed for extreme environments (offshore, chemical, pulp/paper) | |
| Visibility | Large, easy-to-read chart | |
| Reliability | Simple electromechanical design with minimal electronics | Proven long-term operation |
