255-100 根据蒸发皿中的水位变化来测定蒸发率。蒸发计产生输出电阻可以被数据采集器检测到。255-200或其它标准的国家气象服务A级蒸发皿需单独采购。
255-100 包括一个浮标、滑轮和平衡装置,它们装在一个精密的1000-ohm的电位计上,通过齿轮装置安装在防水外箱里面。配有带三个水平螺母和一个水平仪的三角板。电位计产生的输出阻抗与浮标的方位成比例,现场利用数据采集器,或远程使用监测设备可检测到传感器的信号。
255-100 可直接放在蒸发皿中,或是使用255-100P/F与蒸发皿连接。 如不使用255-100P/ F,可使用1/2-英寸的polybraid(纤维加固)软管,尼龙接头(1/2-英寸,NPT X Hose Bar)和小型不锈钢喉箍,这些配件可从当地的五金商店购买。
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.) |
Potentiometer Accuracy | 0.25% |
Rotation | 360° continuous |
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. |
Linearity | 0.25% |
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) |
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 |
Reverse Excitation | Yes |
Measurement Integration |
50 or 60Hz |
Settling Time | 20000 µs |
Multiplier | Determined during installation (see manual) |
Offset | Determined during installation (see manual) |