A bubbler panel controls the liquid level within a filter vessel. A problem that can occur with bubbler panels is “valve hunting,” when there are large swings in water levels of six inches or more. When this happens there are two areas that need to be checked, the bubbler dip tube located within the filter cell and the reversing relay located inside the panel.
When checking the bubbler dip tube, remove from the tank and check for obstructions inside the tube by blowing air through it. (NOTE: Before removing the dip tube, mark placement of dip tube with a permanent marker to ensure proper depth upon replacement.)
When inspecting the reversing relay, also referred to as the 40-L, turn off the air supply. Remove the restriction screw located on the bottom of the 40-L, just left of the arrow. Remove the knurled cleaning wire located on the bottom, just right of the arrow. Run the cleaning wire through the orifice at the tip of the restriction screw. The restriction screw can be soaked in solvent to dissolve any blockage. Examine the “O” ring for damage and replace if needed. Then reassemble.
Not all bubblers react in the same way. What steps may fix one, may not always resolve issues with another. If these steps do not provide a resolution, consider the following questions:
How far down is the dip tube located in the water? Depth can be a factor. Most commonly the dip tube is placed 4" to 6" into the water; if the depth is less than this, the bubbler may not work correctly. Sometimes, placing the dip tube further into the water will help smooth out performance.
What is the appropriate set point for the “20 PSI” regulator? 27 or 28 psig is optimum but we recommend never exceeding 30 psig.
What is the greatest open percentage that the modulating valve will ever see during normal modulation? You can reduce the control pressure to the modulating valve by adjusting the OEM Module “69-1.” This module restricts the maximum percentage that the modulating valve can open. You can artificially create a high level, which causes the valve to go full open, and then reduce the pressure on the “69-1” (by turning the screw out) to where the valve is no less than 80% open. This can act in greatly in preventing the occurrence of valve hunting.
We recommend a weekly maintenance schedule. Check condensation in the air filters located by the air compressor and the bubbler panel. Drain off as needed. It is critical for continued optimal performance to have clean, dry air to the panel. The bubbler dip tube and reversing relay should be cleaned on a yearly basis.
Have additional questions or in need of a panel upgrade? Contact us today.
U.S. Water’s Performance Index series is designed to share operations and maintenance best practices with plant personnel. The more our customers know about how to maintain and protect their systems, the more they can safeguard against system failures or efficiency issues.