John Crane 93AX Coaxial Separation Seal – Why It Can Reduce Nitrogen Consumption by Up to 80%

We recently spent time studying the engineering behind the John Crane 93AX Coaxial Separation Seal, and the design is genuinely impressive. For many compressor operators in Thailand, nitrogen consumption and carbon dust contamination are ongoing pain points. The 93AX directly addresses both issues with a completely different approach to separation sealing.

Here are the key engineering features that enable the up to 80% nitrogen reduction:

1. Coaxial Flow Path vs. Traditional Radial Injection
Conventional segmented carbon separation seals rely on radial nitrogen injection to keep dirty process gas out of the dry gas seal. This creates continuous leakage because nitrogen must “flush” across the sealing faces, and the carbon rings lift as they wear.

The 93AX uses a coaxial nitrogen injection path, a major design shift:

• Nitrogen flows axially through a narrow, controlled annulus
• Seal geometry sharply limits cross-flow leakage
• Pressure control becomes extremely stable
• Bleed-off losses drop dramatically

This is the foundation for large nitrogen reductions.

2. Non-Contacting Aerodynamic Lift-Off Rotor
The 93AX introduces a small aerodynamic lift mechanism that allows the rotor to operate with no rubbing:

• Near-zero friction
• No mechanical wear
• Clearances remain constant over time

This stable operating clearance directly translates to predictable, very low nitrogen flow rates.

3. Pressure-Responsive Micro-Clearance Control
The seal dynamically adjusts to maintain an optimal micro-clearance based on differential pressure.
Compared to carbon rings:

• Carbon leaks increase as the rings wear
• Nitrogen demand rises over time
• Performance becomes inconsistent

The 93AX avoids this degradation, keeping nitrogen usage flat and extremely low.

4. Nitrogen Flow Rate Reduction
Typical nitrogen consumption:

• Carbon separation seals: 8–12 Nm³/hr per seal\
• John Crane 93AX: 1.5–3 Nm³/hr per seal

This is where the up to 80% reduction comes from — and in some cases, operators report even higher savings.

Additional Advantages for Operators
✓ No carbon dust contamination
Traditional carbon seals generate dust that:

• Damages secondary DGS seals
• Clogs seal gas filters
• Causes premature seal failures

The 93AX is dust-free.

✓ Ideal for dirty or polymerizing services
The design performs exceptionally well in:

• Sour gas
• Heavy hydrocarbons
• Wet gas compressors
• Flash gas compressors
• Amine systems
• Polyethylene/propylene processes

No rubbing = no wear = no degradation in performance.

✓ Retrofit-friendly design
Fits many existing carbon separation seal cavities with minimal casing modification.
This makes it a strong upgrade option during scheduled overhauls — especially relevant for:

Why This Matters for Thailand’s Plants
With rising nitrogen production costs, stricter reliability expectations, and more demanding gas compositions, the 93AX offers a major operational advantage. For customers looking to reduce operating costs and eliminate carbon contamination risks, this technology should definitely be evaluated.

At PSS Group, we are continuously exploring modern solutions that directly improve reliability, safety, and lifecycle cost for rotating equipment in Thailand.

If you’d like a deeper assessment or want to explore retrofit potential for your compressors, feel free to reach out.