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Large-Scale PSA CMS Removal and Replacement Procedure

Updated

This article provides general instructions for removing and replacing Carbon Molecular Sieve (CMS) in a large-scale PSA nitrogen generator.

Because of the scale of these systems, CMS removal and replacement require proper equipment, planning, and safety precautions. Manual scooping is typically not practical. A heavy-duty industrial vacuum system and appropriate collection containers should be used for removal, and the replacement media should be loaded in a controlled manner to prevent contamination or damage to internal components.

Before beginning work, ensure the system is fully shut down, isolated, depressurized, and safe to open.

Safety Data Sheet (SDS)

Review the applicable SDS before handling or removing CMS material.

Download the CMS Safety Data Sheet (SDS)

Important Safety Information

Warning: CMS changeout should only be performed by qualified personnel familiar with pressurized systems, lockout/tagout procedures, and confined work hazards associated with large vessels.

  • Depressurize the system completely and vent all pressure to atmosphere.
  • Lock out and tag out all electrical and pneumatic energy sources.
  • Ensure the work area is well ventilated.
  • Use oxygen monitoring where personnel are working near open vessels or enclosed areas.
  • Wear appropriate PPE, including respirator, gloves, and eye protection.

CMS dust is an irritant and can be extremely messy. Good housekeeping and dust control should be maintained throughout the process.

Safety Note: Wet activated carbon can remove oxygen from the air and may create a severe hazard inside carbon vessels and other enclosed or confined spaces. Ensure the area is properly ventilated and monitored before personnel begin work.

Required PPE

  • N95 or P100 respirator, or other approved particulate respirator suitable for dust exposure
  • Safety glasses or goggles
  • Gloves
  • Protective clothing as needed for dust exposure

Tools and Equipment Required

For Removal

  • High-CFM industrial vacuum capable of handling dense media
  • Heavy-duty vacuum hose suitable for bulk solids
  • 70 kg collection barrels or similar high-capacity containers
  • Industrial-strength removable barrel liners or bags
  • Oxygen monitor (recommended)
  • Standard hand tools for opening vessel access points

For Replacement

  • Replacement CMS material in the correct quantity and specification
  • Clean transfer equipment, funnels, loading sock, or other controlled fill method
  • Clean containers or staging bins for media handling
  • Flashlight and inspection mirror
  • New gaskets or seals for access covers if required
  • Torque tools as needed for reassembly

CMS Removal Procedure

1. Prepare the System

  1. Shut down the nitrogen generator in accordance with site procedures.
  2. Isolate the system from all incoming air and downstream demand.
  3. Fully depressurize both PSA towers and confirm they are vented to atmospheric pressure.
  4. Apply lockout/tagout to all relevant energy sources.
  5. Verify that the work area is safe, ventilated, and monitored as required.

2. Set Up Removal Equipment

  1. Position the industrial vacuum near the PSA vessels.
  2. Prepare lined collection barrels for the removed CMS.
  3. Confirm that lifting, hose routing, and barrel handling can be completed safely.
  4. Open the top handway or manway of each PSA tower.

3. Remove the Existing CMS

  1. Lower the vacuum hose into the media bed through the top opening.
  2. Remove media gradually, working in a circular pattern to keep the bed level as it drops.
  3. Avoid plunging the hose straight down and allowing it to bury itself in the media.
  4. As each collection barrel approaches its weight limit, stop and seal the liner before moving to the next barrel.
  5. Continue until all CMS has been removed from the vessel.

4. Inspect Internal Components

Once the media has been removed, inspect the vessel internals before loading new CMS:

  • Bottom support screens
  • Internal distribution components
  • Retaining hardware
  • Vessel interior surfaces

Look for:

  • Screen damage
  • Broken or loose internal hardware
  • Oil contamination
  • Excessive fines or debris
  • Moisture intrusion

Any damaged or contaminated components should be addressed before new CMS is installed.

5. Dispose of Removed Media

Used CMS is typically considered non-hazardous, but it may contain trapped particulates or contaminants from operation. Disposal requirements may vary by location.

Check with your local waste management provider for guidance on disposal of carbon-based adsorbent material.

CMS Replacement Procedure

1. Verify Readiness for Refill

  1. Confirm the vessel interior is clean and dry.
  2. Confirm internal screens and support components are in good condition.
  3. Verify the correct CMS specification and total fill quantity for the system.
  4. Ensure all tools, funnels, hoses, and staging containers used for refill are clean and free of oil, dirt, or moisture.

Important: Do not load replacement CMS until the vessel internals have been inspected and any issues corrected.

2. Prepare the CMS for Loading

  1. Stage the replacement CMS near the vessel in a clean, dry indoor area.
  2. Keep the media sealed until ready to load.
  3. Protect the CMS from exposure to rain, humidity, oil, or airborne debris.
  4. If multiple containers are being used, confirm the total quantity matches the required fill amount for each tower.

3. Load the New CMS

  1. Open the vessel top access point if not already open.
  2. Using a clean funnel, loading sock, or other controlled fill method, begin adding the new CMS into the vessel.
  3. Load the media slowly and evenly to avoid damaging internal components or creating unnecessary dust.
  4. Periodically level the media bed as required during filling.
  5. Avoid dropping large amounts of CMS from excessive height, as this can create fines and uneven packing.
  6. Continue until the specified fill volume or weight has been reached.

4. Verify Fill Condition

  • Confirm the proper media level has been achieved.
  • Confirm the bed is reasonably even across the vessel.
  • Verify no foreign material has entered the vessel.
  • Inspect the access opening and sealing surfaces before closure.

5. Reassemble the Vessel

  1. Install the access cover using the correct gasket or seal.
  2. Tighten hardware evenly and in the appropriate pattern.
  3. Torque fasteners as required by the equipment manufacturer or service standard.
  4. Confirm all tools and loose materials have been removed from the work area.

Startup and Post-Replacement Checks

  1. Return the system to service in accordance with standard startup procedure.
  2. Check for leaks at all opened access points.
  3. Verify valve operation and cycle sequencing.
  4. Replace mufflers and filters as applicable during the PM event.
  5. Perform any required valve rebuild work.
  6. Tune the system as needed to restore proper nitrogen purity and performance.
  7. Confirm final operating condition, including:
    • Nitrogen purity
    • Flow performance
    • Pressure stability
    • Cycle timing
    • Alarm status

Note: Final tuning and performance verification should be completed by qualified service personnel.

Best Practices

  • Do not mix old and new CMS.
  • Do not expose replacement CMS to moisture before installation.
  • Do not reuse contaminated media.
  • Keep all refill tools and components clean and oil-free.
  • Inspect vessel internals carefully before reloading.
  • Record the quantity of CMS removed and installed for service documentation.

Storage and Handling Notes

  • Store packaged CMS indoors.
  • Do not leave replacement media exposed to weather.
  • Clean spilled material by sweeping or vacuuming while minimizing dust generation.

When to Contact South-Tek

Contact South-Tek for support if any of the following are found during the changeout:

  • Damaged support screens
  • Oil contamination inside the vessel
  • Excessive dust or fines beyond normal expectation
  • Uncertainty regarding correct media quantity or specification
  • Difficulty restoring purity or flow after replacement

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