SterliTECH Tip: Removing Hold Up Volume from Cross Flow Systems Using Pressurized Air

Hold up volume in Skid Mount Membrane Systems can lead to inefficiencies, contamination, and inaccurate measurements. Removing it is essential for optimal performance in filtration and process applications. Alongside our Vacuum Recovery Kit, another effective method is using pressurized air to purge unwanted fluid from lines, valves, and fittings. 

What You'll Need 

  • A source of clean, dry pressurized air
  • Access to the system's compression fittings (e.g., feed and concentrate bulkheads) 

Steps to Remove Hold Up Volume 

  1. Isolate the target section. Our systems have two lines: the main feed line and the bypass line. Identify which line you want to purge.
  2. Close the bypass valve. If purging the main feed line, ensure the bypass valve is fully closed before proceeding.
  3. Connect the air line. Remove an accessible compression fitting in the target line — such as the feed or concentrate bulkhead on top of the skid — and connect your pressurized air source there.
  4. Gradually apply air pressure. Slowly increase air pressure and direct airflow through the section, forcing any residual liquid out. Keep the tank cover closed to prevent splashing.
  5. Repeat for additional lines. Connect the air line to the appropriate port for each remaining line, closing the relevant valves as needed, and repeat the purge process. 

Pro Tip: If you plan to do this regularly, consider installing a T-fitting with a ball valve on the feed line. This makes it quick and easy to connect the pressurized air line without removing fittings each time. 

 Ask an expert today if you have any questions about maintaining your system.