ACCURATE TO WITHIN 1° F
WIDE VARIETY OF TEMPERATURE RANGES AND CHART SPEEDS
BANJO-TYPE HUMIDITY SENSOR FOR FAST RESPONSE
PORTABLE-REQUIRES NO ELECTRIC POWER
MEETS NATIONAL WEATHER SERVICE SPECIFICATION NO. 450-8202.

Specifications | Options | Charts | Related Equipment | Ordering Information

The Belfort Hygrothermograph, Model 594, is a combination temperature and relative humidity recorder. Dual sensing - elements provide inked traces on a single, dual-trace rectangular chart. The temperature pen is actuated by either a liquid-filled bourdon tube or a bimetallic element. Humidity pen movement is caused by the increase or decrease of humidity acting on a human hair element causing it to expand or contract. The unique "banjo" type hair element is constructed of several small hair bundles arranged in parallel. This allows for better aspiration of the individual hairs, which results in an improved and faster response time.

The instrument is housed in a hinged metal case with a handle on top for easy handling and a window that allows for an unobstructed view of the chart record. Sides of the case are open to permit free air flow to the sensing portion of the instrument.

The spring powered chart drive is driven through an appropriate pair of time-scale gears by a dual-output mechanism capable of providing more than 8 days of operation. Timing of the mechanism is controlled by an 11 - jewel, lever-type escapement.

The optional battery-powered chart drive is similar to the spring powered drive, but the mechanism has three output speeds and is powered by two C-cell batteries. Alkaline cells permit operation of the drive from -40° to +125° F for periods of up to three months. Timing of the mechanism is managed by a quartz crystal controlled oscillator. The timing accuracy of both spring/battery powered drives is 14 min/week over the range of -40° to +125° F (-40° to +51° C).

Specifications

Range: See chart table
Accuracy: Temperature ±1°F between -20° to 110°F (-28° to 43°C)
Sensitivity: Humidity 1% RH at room temperature
Finish: Beige and brown enamel
Overall Dimensions: 13.25in(33.7cm)L 6in(15.3cm)W 9.75in(24.8cm)H
Weight: 10lbs(4.5kg)
Shipping weight: 17lbs(7.7kg)

Options

Four models of the Belfort Hygrothermo-graph are currently available; the 594 and 594-2 models use the bourdon tube temperature elements while the 594-1 and 594-3 models use a bimetal temperature element. If the instrument is not to be installed in an instrument shelter, the 594-2 or 594-3

Thermoshield model should be ordered to help reduce radiant heat effects. All models are available with either spring-powered or electric chart drive and use any of the range and chart speed combinations listed.

Charts

1. All Summer and Winter charts are directly interchangeable, with only a zero adjustment in the instrument
2. Least division of range is 2° for a 1° C.
3. Chart for use with electric chart drive only

Related Equipment

Ordering Information