EagleBurgmann - Bi-Directional Gas Seals, Gas-Lubricated Metal-Bellows Seals, Elastomer-Free Gas-Lubricated Compressor Seals

EagleBurgmann is one of the world's leading manufacturers of seal systems, currently employing a workforce of about 4,100 people in over 50 subsidiaries and joint-ventures worldwide. In spite of a tough economic environment sales have continually risen, reaching approximately €342 million in 2005.

Burgmann Industries forms an impressive worldwide cooperative alliance with Eagle Industry (the Japanese mechanical-seal manufacturer) called EagleBurgmann Industries (EBI).

EBI offers customers environmentally compatible solutions; standardisation and application testing; installation, start-up, repair and damage analysis services; and practical training and seminars on sealing technology.

EBI products afford maximum safety, are reliable, and can be utilised in virtually all industries, including power stations, the chemical industry, refineries, shipbuilding, marine engineering, aerospace, offshore installations, automotive engineering, paper-making and sugar-production.

EagleBurgmann's product-range includes:

• Mechanical seals
• Gas-lubricated seals
• Seal supply systems
• Magnetic couplings
• Stuffing-box packings
• Static seals
• Expansion joints
• Automotive seals
• Rotary-kiln sealing systems
• 'TotalSealCare' service

DGS NON-CONTACT BI-DIRECTIONAL GAS SEALS FOR TURBOCOMPRESSORS

Burgmann's DGS non-contact bi-directional dry-gas seals are increasingly being used to seal turbocompressors. The DGS' sealing concept considerably reduces capital expenditure and operating costs compared to oil-lubricated seals.

The basic design of the DGS non-contact bi-directional dry-gas seal is similar to conventional mechanical-seals. The seal ring is stationary and flexibly mounted on springs, while the V-grooved rotating seal is inserted in a purpose-designed carrier on the seal sleeve.

Rotation of the seat conveys the gas into the V-grooves. As the gas moves along the grooves it causes the flexible member to lift off, enabling the seal to operate without contact in-between the faces.

The Burgmann DGS' seal-face grooves are shaped like a half-moon instead of a "V," making it capable of operating in both directions.

MFLC-GS GAS-LUBRICATED METAL-BELLOWS SEAL

Burgmann's MFLC-GS gas-lubricated metal-bellows seal, for pumps in extreme cryogenic applications (for example with liquid nitrogen), possesses an innovative design that ensures safety and efficiency: the loosely inserted carbon seal-face is sealed by surface contact between carbon and bellows. This obviates the need for a secondary seal that can cause low-temperature leakage.

A metal bellows unit made of Inconel 718 ensures axial closing-pressure in unpressurised mode. Optimised aerodynamic gas-grooves guarantee contact-free running whatever the pump's operating status.

The power consumption of the sliding faces and the pressure-drop over the sealing-face width result in a two-phase flow in the sealing gap. The MFLC-GS gas-lubricated metal-bellows seal uses this to separate the sliding faces, thereby ensuring friction-free operation.

The single-acting metal-bellows seal is manufactured in compliance with EN13275 and EN12300, meaning all components that come into contact with the respective product are constructed from BAM (Federal Institute for Material Research and Testing) approved materials for applications in oxygen.

The seal-face's protective sleeve and axial seat-lock are bronze, and the standard sliding-face pairing is carbon-graphite against tungsten-carbide. This combination is highly reliable, prevents sparking, and easily survives temporary contact between the sliding faces.

The operating limits of the MFLC-GS gas-lubricated metal-bellows seal are:

• Pressure (p1): 2bars to 15bar
• Temperature (t1): 196°C
• Sliding velocity (vg): approximately 5m/s to 50m/s
• N: 3,000rpm (with a stationary pump), or 7,000rpm to 11,000rpm (with a mobile pump)
• Media: oxygen, nitrogen, argon, etc.

PDGS ELASTOMER-FREE GAS-LUBRICATED COMPRESSOR SEAL

Burgmann's new PDGS elastomer-free, gas-lubricated mechanical seal was specially developed for extreme requirements in high-pressure and low-temperature applications.

The PDGS provides stable leakage rates and reliable operating characteristics in all operating ranges. Excellent mobility of the purpose-developed dynamic secondary-seals is typical in low-temperature duty.

The PDGS elastomer-free, gas-lubricated compressor seal ensures high operational reliability through:

• Spring-reinforced special-compound constructed secondary-seals with PTFE-level chemical-resistance
• No explosive decompression
• Dynamic secondary-seals back-up rings and balancing sleeves, made of tungsten carbide for zero radial-shrinkage and a small controlled-extrusion gap
• Optimised secondary-seal sliding properties, without "catching"
• Optimised aerodynamic gas-grooves
• Optimal sliding properties during start-up
• Maximum gas-film rigidity, even at low pressure
• Self-cleaning
• Ceramic-compatible design with friction-locked torque-transmission of the rotating seat
• No stress-increasing shaping operations
• Diamond-like DLC coating on the seal faces

The operating limits of the PDGS elastomer-free seal are:

• Shaft diameter: 25mm to 320mm
• P1: 1bar to 350bars
• T1: 170°C to 230°C
• Vg: 200m/s