Advantages of Dual Gas Seals
• No product emissions
– gas pressure provides barrier to product leakage
• No product contamination
– uses inert barrier gas such as nitrogen
• No seal face wear
– noncontacting APGS face technology
• Protected from off-design pump operation
– tolerant of vibration, cavitation, dry running
• Minimal power consumption, no heat generation
– 15-20 times less energy loss than liquid seals
• Simplified barrier support system
– unitized control panel
– dead-ended gas supply
– no external cooling required
• Low total operating cost
– no routine maintenance
– inexpensive barrier gas


Technology Considerations
• Groove pattern design - film stiffness, low speed lift-off, gas consumption
• Secondary seal drag - seal face hang up
• Operating conditions - seal face distortion, vibration, batch operation
• Product effects - solids, polymers, etc.
• Gas reliability - barrier system design
• Safety during upset events - pressure reversal, reverse rotation, slow speed


Advantages of APGS Technology
• Patented tapered depth and tapered width spiral grooves with unifying circumferential groove
• High film stiffness with low gas leakage
• Adaptable to various application types:
– high speed, high pressure compressors
– low speed mixers
– variable speed pumps
• Over 2500 installations in pump gas seal and compressor services

Flowserve Pump Gas Seals
• GF-200
– Face to face pusher design
– Fits large bore seal chambers only
– High pressure capability
– Extensive exotic materials availability
• GX-200
– Common rotor welded metal bellows design
– Fits both small bore and large bore seal chambers
– Solids resistance features
– Pressure reversal product containment



GF-200 Operating Limits
Product Pressure: 500 psig (34.5 bar)
Barrier Pressure: 25 psi (2 bar) minimum over product pressure
Temperature: -40 to 500 F (-40 to 260 C)
Minimum Speed: 500 ft/min (2.5 m/sec)
Maximum Speed: 7000 ft/min (25 m/sec)
Seal Sizes: 1.000” to 6.000” (25.4 mm to 150 mm)




GX-200 Operating Limits
Product Pressure: 200 psig (34.5 bar)
Barrier Pressure: 25 psi (2 bar) minimum over product pressure
Temperature: -40 to 500 F (-40 to 260 C)
Minimum Speed: 500 ft/min (2.5 m/sec)
Maximum Speed: 7000 ft/min (25 m/sec)
Seal Sizes: 1.000” to 3.000” (25.4 mm to 76 mm)


Application Considerations
• Barrier Gas Reliability
– Pressure reversals are a primary reason for seal upset
– Install alarms and emergency backup supply
• Fluids with Solids
– Gas seals are not slurry seals - product at seal face ID
– Gas may cause dissolved solids to come out of solution
– Use bushings to keep solids from seal faces
• Reverse Rotation of Pumps
– APGS gas seal faces contact when reverse rotated
– Check piping, shutdown procedures, and motor wiring
• Transient Slow Speed Cycles
– Check all equipment cycles for minimum speeds
– Minimize start and stop parameters on VFD’s
• Stand-by Pumps
– Small static gas leakage can accumulate over time
– Properly vent pump before start-up
• Low Flow / Low Suction Head Pumps
– Centrifugal pumps can tolerate 1-2% entrained gas
– Gas leakage expands in low pressure suction
– Evaluate gas percentage at lowest pressure point

Conclusions
• Flowserve Flow Solutions Division GF-200 and GX-200 noncontacting seal face gas barrier seals provide extended pump reliability solutions using proven, patented technologies.
• Zero product emissions, no contamination of the product, no seal face wear, tolerance of offdesign pump operation, negligible energy consumption, simple installation, and low maintenance requirements add up to low total operating costs.
• APGS face design produces a stable gas film for consistent loading, early face separation, high film thickness, and low gas leakage.
• The GF-200 is a face to face pusher design using LoDrag™ energized O-rings to minimize secondary seal drag. Fitting only on large bore seal chambers, it is capable of sealing 500 psi (34.5 bar) with a variety of optional materials of construction.
• The GX-200 is a common rotor design which eliminates secondary seal drag altogether with Alloy C-276 or Alloy 718 bellows. It fits any seal chamber size by mounting entirely outside and has standard solids tolerance features.
• Ask Flowserve for information about gas seal solutions for other equipment such as mixers, compressors, or steam turbines where low speed, high pressure, and/or high temperature create difficult sealing environments.

Flowserve Gas Seal Products
Product      Technology       Arrangement       Equipment        Special Feature
GSD           Contacting              Backup                  API                Emergency containment
GSL               Wavy                   Backup                  API                High duty containment
GB-200        Hydropads            Double             ANSI big bore     Pressure reversals
GF-200           APGS                 Double             ANSI big bore     Low drag O-rings
GX-200          APGS                 Double          ANSI small bore     Metal bellows
GF-300           APGS                Tandem                   API                 Flashing hydrocarbons
GTS                Wavy                 Single               Steam Turbine      High temperature steam
GSS                Wavy                   All                     Sundyne             High speed, small size
Gaspac       APGS, T-groove      All                   Compressor          High speed, large size
VRA            Contacting        Single/Double          Mixers              Low speed
ML-200          APGS                  Double                Mixers              Low speed