Campbell Scientific 255-100 Novalynx Analog Output Evaporation Gauge - Manual (Page 5)

255-100 Novalynx Analog Output
Evaporation Gauge
1. General
Novalynx Corporation manufacturers the 255-100 Analog Output Evaporation
Gauge and the 255-200 Class A Evaporation Pan. The 255-100 consists of a
stilling well and potentiometer based shaft encoder. It is a low-power option
for reading the water level of an evaporation pan such as the 255-200.
The 255-100 consists of a chain-mounted float and counter weight that turns a
sprocket attached to a precision 1000 ohm potentiometer. When provided with
a precision excitation from the datalogger, the NovaLynx 255-100 Evaporation
Gauge produces a DC voltage that changes proportionally to the change in
water depth of the evaporation pan. The datalogger measures the voltage to
determine water level and, consequently, evaporation and rainfall. Using the
255-100P/F Steel Pipe & Fittings, the gauge may be installed outside of, but
hydraulically connected to the pan. This configuration will prevent the gauge
from interfering with the wind flow over the pan or from altering the solar
loading on the pan. A pipe connects the pan to the gauge keeping both at the
same “head”.
Evaporation pans need to be refilled from time to time. Depending on the local
rainfall, the pan should be filled to about 2 to 3 inches below the top. The
evaporation pan can be refilled automatically with the 255-620 Automatic
Refill Kit. More precise refill control can be done by programming the
datalogger to control a solenoid valve. Programming the datalogger for
partially draining the evaporation pan, using a second solenoid valve, may be
desirable if the site regularly experiences heavy rainstorms. Refer to the
section on Automatically Refilling the Evaporation Pan in this document for
more information.
Fences or other deterrents are required to prevent animals from
using the evaporation pan as a watering trough. NOTE
1