CHAPTER 6 - MEASURING AND RECORDING WATER STAGE OR HEAD
9. Operation, Maintenance, and Care of Water-Stage Recorders
Standard procedures for operation of water-stage recorders should include verifying correct operation of the type of recorder present, checking that water elevations inside and outside of the stilling well match, inspecting and cleaning the intake pipe to the stilling well, and verifying that clocks (if so equipped) are operating properly. Inspections at regular, short intervals are generally required to keep breaks in data at a minimum. Persons installing and servicing water-stage recorders should follow manufacturers' recommended instructions for that particular instrument. These instructions should be placed conspicuously inside the instrument case or shelter.
Recorder enclosures should be well ventilated to prevent excessive humidity from affecting operation. Moist air can be excluded from the recorder by a partition over the stilling well. Instrumentation for detecting and correcting errors caused by high humidity is available if necessary.
Condensation within the recorder cover and metal shelters can be alleviated by gluing or spraying a resistant coating (such as cork) inside of each. Silica gel can be used as a desiccator, but it must be replaced occasionally or the moisture must be removed from the gel by heating in an oven at 300 degrees Fahrenheit.
The well and shelter must be maintained in good condition, the intake pipes must be kept open, and the well must be protected from ice and drift. Freezing weather may require heating the well with an electric heater or a cluster of lights. A layer of low-freezing-point, environmentally safe oil in the float well equal to the greatest thickness of ice expected can also be effective. In the past, oils such as kerosene or fuel oil were used; however, because of the possibility of the oil spilling into the water supply, only nontoxic, environmentally safe oils should be considered for this use.