FTS Bubbler - Orifice Line Connection and Installation

700-Bubbler-Man Rev 12 13 Feb 2020
Page 11/51
3) Cover the tube to ensure no pellets can enter, and tip the desiccant out into a clean, sealable
container.
4) Refill and replace the bowl following steps 4 and 5 in the preceding section.
5) Replace the air dryer in the mounting bracket and replace the desiccant hose, if it had been
removed.
6) Supply power to the Bubbler.
2.6 CONNECTING AND INSTALLING THE ORIFICE LINE
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The orifice line should be black polyethylene 3/8” outer diameter, 1/8” inner diameter USGS
approved.
The orifice line should be enclosed in a protective conduit to prevent damage from foot traffic,
animals, debris, etc. The run should be as straight as possible in a continuous downward path to
minimize moisture collection in catenaries. No part of the line should be lower than the line exit in
the water. The run should terminate in a calm area, ideally in the same pool as the outside gauge,
and secured so that the stream ward end with the line outlet will remain in a fixed position and at a
depth that will not be exposed at low stage. The stream ward end should be positioned
perpendicular to the direction of the flow at a slight downward angle.
The use of an orifice fitting on the terminal end of the orifice line is recommended to aid in securing
the line in a fixed position. There are a variety of orifice options available to the consumer
depending on site characteristics and specific agency requirements. FTS offers the USGS Standard
Orifice Fitting (Part #19063) as an accessory.
If the area has high currents, the orifice line should be installed in a static tube. If the waters are
turbulent, a muffler should be used.
Once the orifice line run is securely laid out, connect the orifice line to the Bubbler outlet (refer to
Figure 2-5) and secure it with the provided Swagelok® fitting.
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For a detailed explanation of the installation of an orifice line and static tube, refer to USGS publications:
TWRI_8-A2: Craig, J.D, 1983, “Installation and service manual for U. S. Geological Survey manometers”: U.S. Geological Survey
Techniques of Water-Resources Investigations, book 8, chap. A2. http://pubs.usgs.gov/twri/twri8a2/html/pdf.html
TM3-a7: Sauer, V.B. and Turnipseed, D.P., 2010 “Stage Measurement at Gaging Stations”: U.S. Geological Survey Techniques
and Methods, book 3, chap 7, sect A http://pubs.usgs.gov/tm/tm3-a7/pdf/tm3-a7.pdf