Fieldpiece ARH4
Digital Sling Psychrometer Accessory Head

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Fieldpiece ARH4 Shown
Product Information
Flyer 899 KB PDF Datasheet
Manual 229 KB PDF Datasheet
PDF HelpPDF Help
  • Measures Temp and RH%
  • Calculates wet bulb and dew point temperatures
  • Get outdoor dry bulb and indoor wet bulb for target superheat calculations
  • Log relative humidity over time and troubleshoot systems
  • English and Metric units
  • Auto Power-Off (APO) to extend battery life, with override switch for data logging and extended test times

The Fieldpiece ARH4 Digital Sling Psychrometer Accessory Head measures both relative humidity and ambient air temperature. The Fieldpiece ARH4 calculates dew point and wet bulb. The Fieldpiece ARH-4 is great for calculating target superheat as well as logging %RH, temp, WB or DP over time. The Fieldpiece AR-H4 Psychrometer Accessory head converts %RH, ambient temperature, dew point temperature, and wet bulb temperature to a voltage at a rate of 1 %RH or degree to 1mVDC and your reading is displayed on your meter. The Fieldpiece ARH/4 snaps directly onto Fieldpiece stick meters, data logger, electronic handles and adapters.

The Fieldpiece ARH4 Psychrometer Head employs an advanced pair of sensors, a thermistor and a hygrometer, that sense temperature and moisture in the air. With built-in psychometric charts, the Fieldpiece ARH4 calculates dew point and wert bulb based on these direct measurements. For the most accurate readings, the user needs to expose the Fieldpiece ARH4 to the air they are measuring for a few minutes so that the sensors can come to equilibrium.

The modular design of the Fieldpiece ARH4 gives it a distinct advantage over other digital psychrometers. The thermistor and hygrometer are highly accurate and designed specifically to stand up to HVAC/R field service. Many competitive standalone psychrometers do not include calculations for wet bulb like the Fieldpiece ARH4. Remote the Fieldpiece ARH4 with our detachable test leads to isolate the area you’re testing and measure or log readings in hard to reach areas. Like all of our accessory head instruments, the modular design means the fieldpiece ARH4 takes up less space on the truck while providing accurate measurements and calculations.

Temperature Sensor: thermistor temperature sensor
Range: -4°F to 140°F (-20°C to 60°C)
Resolution: 0.1°C / 0.1°F
Accuracy: ±1°F: 32°F to 113°F
±2°F: -4°F to 32°F, 113°F to 140°F
±0.5°C: 0°C to 45°C
±1°C: -20°C to 0°C, 45°C to 60°C
Output: 1mV/°C,1mv/°F
Relative Humidity Sensor: Capacitive humidity sensor
Range: 0% to 100%RH
Accuracy: ±2.5%@77°F(25°C), 10% to 90% RH
±5%@77°F(25°C), 90%RH
Output: 1mV/%RH
Sensor response time: 60 seconds typical for 90% of total range
Sensor hysteresis: (excursion of 10% to 90% to 10% RH): ±1%RH typical
Range: 32°F to 140°F
Accuracy: ±1°F (32°-113°F)
Low battery indication: Red LED is lit when the voltage drops below the operating level
Output impedance: 500W approx.
Operating environment: 32°F to 120°F (0°C to50°C) at <95%RH
Storage temperature: 4°F to 140°F (-20°C to60°C) <80%RH with battery removed.
Dimensions: 146mm(H) x 67mm(W) x 32mm(D)
Weight: 180g including battery approx.
Warranty: 1 year
Ordering Information
Model Description Buy Online Price
ARH4  Fieldpiece ARH4 Digital Sling Psychrometer Accessory Head Buy Now Sale $76.80
(Reg. $96.00)
Included Accessories
  • 1 - 9-Volt battery (installed)
  • 1 - Operator’s manual
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