How to Retrofit a Mist Eliminator That Has Sagged or Compressed in Service

A wire mesh pad or other flexible separator can lose its intended geometry over time.

The pad may sag between supports, compress under its own weight or liquid load, or become locally crushed during maintenance.

These mechanical changes alter both pressure drop and separation behavior.

Replacing the separator with the same specification without correcting the structural cause can reproduce the problem.

Identify the Type of Deformation

Sagging and compression are not the same.

Sagging creates an uneven elevation profile.

Compression reduces thickness and open volume.

A separator may experience both simultaneously.

Check Support Spacing

Large unsupported spans can allow flexible mesh sections to sag.

The support grid should provide sufficient support without excessively blocking gas flow.

If sagging occurs repeatedly between the same bars, support spacing deserves review.

Check Liquid Accumulation

Poor drainage can make the separator much heavier during operation.

A mesh pad saturated with liquid experiences greater downward load.

Improving drainage can therefore reduce mechanical deformation as well as carryover.

Inspect Installation Compression

Mesh pads are sometimes forced into undersized frames.

Excessive compression changes density and increases pressure drop.

The new retrofit should use correct dimensions and controlled fit.

Review Deposit Weight

Fouling adds mass.

Heavy scale or polymer can cause sections to sag even when clean support design was adequate.

The retrofit should therefore address fouling as well as mechanical strength.

Check Gas Force

High upward gas velocity can create movement in the opposite direction.

Repeated upward and downward forces may loosen or distort the separator.

The operating gas range should be reviewed.

Restore Correct Pad Thickness

For mesh, nominal thickness matters.

A severely compressed old pad may no longer provide the intended coalescing path.

Simply cleaning it may not restore geometry.

Replacement is usually more reliable if deformation is permanent.

Improve Support Without Overblocking

Additional support bars can reduce sag but increase gas resistance.

A well-designed grid balances:

• mechanical span;
• free area;
• drainage.

Check Section Joints

Sagging can open gaps between modules.

This creates gas bypass and worsens carryover.

The new design should maintain joint contact across the support system.

Review Handling Procedures

Maintenance personnel standing on or placing tools on mesh pads can permanently deform them.

Access procedures and protective platforms may be needed.

Verify Pressure Drop After Retrofit

A correctly supported pad should show stable pressure drop across the operating range.

Unexpectedly high resistance can indicate excessive compression or incorrect density.