Explain the mechanism of Stevens ‘F’ type stage level recorder?by Madan Mohan
The US Type F Water Level Recorder is an inexpensive, accurate versatile recorder for general-purpose recording including:
- Stream gaging
- Water supply
- Ground water studies
The Type F Water Level Recorder is an instrument for permanently recording varying levels of any liquid surface. Among other uses, flow data may be obtained by use with weirs, Parshall flumes or other rated measuring structures in which heights, or differences in heights, are an index of flow.
The rise and fall of the float with changing water levels turns the drum proportionately, as the clock-controlled pen moves across the chart at a constant speed. The resulting graph shows the water level against a record of time. The range in stage is limited only by the length of the float line and float size, since the chart drum may make any number of revolutions.
The time period of recording may vary from 12 hours to 32 days, (depending upon chart, gearing, and type of clock drive). Charts are available with English or metric divisions.
A balanced, ball-bearing mounted chart drum responds to 0.01 ft. (3 mm) change at 1:1 scale, using a 5 in. float. The instrument is actually sensitive to 0.002 foot (0.6 mm) and can record to such a degree of accuracy if a large enough float is employed.
- Accurate quartz multispeed timer (QMT) eliminates need for time scale gear changes. Battery operated time scales corresponding to 32, 16, 8, 4, 2, 1 and 1/2 days of chart operation.
- Compact, portable, self-contained power
- Quick, easy chart changing
- Easy field conversion to vary recording ratio
- Unlimited range in stage
- Charts – with English or Metric scales
- The Recording Pen – The Recorder is supplied with a cartridge style nylon tip pen
- Choice of stainless steel beaded float line or direct reading graduated tape
- Scow float eliminates float well (optional)
Also required for operation and sold separately are one of each of the following:
- Float pulley
- Beaded line or float tape
- End hooks
Gage Scales are required for use and are included in Basic Recorder price. The relation between the rotation of the float pulley and the chart drum is set by gearing. Thus changes in the gearing or the pulley circumference affect the ratio between the chart record and water level changes. This ratio is known as gage scale. To make a field change from any scale listed (except 1:20) to another requires only the substitution of a pair of gears. The 1:20 scales are obtained by installing the 750 mm or 36″ circumference ring on float pulley of a recorder geared for 1:10.
Basic recorder system includes recorder, chart, cartridge type pen with spare cartridge, cast aluminum base and metal cover. Also included is Quartz Multi-Speed Timer equipped with a seven switch selectable time scale for 0.5, 1, 2, 4, 8, 16, and 32 days.
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