The 255-100, manufactured by Novalynx, determines evaporation rate by measuring the changing water level in your evaporation pan. The evaporation gauge produces a resistance output that Campbell Scientific data loggers can monitor. The 255-200 or another standard National Weather Service Class A evaporation pan must be purchased separately.Read More
The 255-100 consists of a float, pulley, and counterweight attached to a precision 1000-ohm potentiometer mounted through a gear assembly in a weatherproof housing. It has a triangular base plate equipped with three leveling screws and a bubble level. The potentiometer produces a resistance output proportional to the position of the float, which can be monitored on site using a data logger or monitored remotely by telemetry equipment.
The 255-100 can be placed directly in the pan, or connected to the pan using the 255-100P/F stainless-steel pipe and fittings. Instead of using the 255-100P/F, a 1/2-in. polybraid (fiber reinforced) flexible tubing, nylon fittings (1/2-in. NPT x Hose Bar), and small stainless-steel hose clamps can be used; this equipment is available from a local hardware store.
|Water Input Port||1/2-in. NPT coupling, female|
|Counter Weight||114 g (4 oz) stainless steel|
|Total Resolution||0.76 mm (0.03 in.)|
|Electrical Angle||340°, ±1° (20° gap)|
|Resistance||1,000 ohm, ±10%|
|Operating Temperature Range||
-40° to +60°C
Evaporation is normally not measured at temperatures below freezing.
|Mechanical Range||0 to 254 mm (0 to 10 in.)|
|Electrical Range||0 to 240 mm (0 to 9.44 in.)|
|Float||10.2 cm (4 in.) diameter, plastic|
|Cable Description||3-conductor, 24 AWG, shielded|
|Cable Length||15 m (50 ft)|
|Diameter||203 mm (8 in.)|
|Height||700 mm (27.5 in.)|
|Base Dimensions||40.6 cm (16 in.) triangle with leveling screws|
|Weight||3.4 kg (7.5 lb)|
|Shipping Weight||6.8 kg (15 lb)|
Number of FAQs related to 255-100: 2
The 255-100 Evaporation Gauge is a potentiometer-type sensor. The 255-100 only draws a few milliamps of power momentarily. If the 255-100 is the only sensor in the system, the data logger has an average power draw of approximately 1 mA.
The Half Bridge instruction should be selected (not the 3 Wire or 4 Wire options) in Short Cut. The following parameters are data logger specific, but the following can be used on the CR1000 datalogger with the sensor wired to SE1, and Vx1:
|How many HalfBr Sensors?||1|
|Total Bridge Resistance||1000 ohm|
|Excitation Voltage||2500 mV|
|Sensors per excitation channel||1|
|Range of sensor voltage||2500 mV|
50 or 60Hz
|Settling Time||20000 µs|
|Multiplier||Determined during installation (see manual)|
|Offset||Determined during installation (see manual)|