Tandem Double Cartridge Multi-Spring Mechanical Seal

Product Overview; 

The DC640 Tandem Double Cartridge Multi‑Spring Mechanical Seal is a high‑performance, hydraulically balanced sealing solution engineered for centrifugal process pumps and rotating equipment handling hazardous, volatile, corrosive and high‑temperature fluids. Designed as a tandem double cartridge arrangement, it places two mechanical seals in series within a single cartridge to provide secondary containment and enhanced leakage control in demanding industrial services. 

 

The seal features precision‑balanced rotating faces, a multi‑spring distributed loading system and a factory‑preset cartridge construction, ensuring stable face loading, improved heat dissipation and simplified, error‑free installation on conventional stuffing boxes, regardless of pump make or model. Mounted on a sleeve with an integrated gland plate, the pre‑assembled cartridge slides directly over the pump shaft or sleeve and is set to its correct operating length, significantly reducing installation time and the need for highly skilled labour. 

 

In a tandem (Arrangement 2) configuration, the inboard seal acts as the primary process seal while the outboard seal operates with a buffer fluid at lower pressure, providing back‑up containment in the event of primary seal degradation. This arrangement is particularly suited to toxic, flammable and environmentally sensitive fluids, supporting improved safety, reduced fugitive emissions and compliance with environmental and process‑safety requirements. The multi‑spring design maintains uniform face loading under fluctuating pressures and temperatures, promoting reliable operation and extended seal life in continuous‑duty service. 

 

Engineered for API process pumps and critical industrial equipment, the DC640 delivers dependable sealing performance across petrochemical plants, refineries, fertilizer units, pulp and paper mills, pharmaceutical facilities, mining operations and power‑generation systems. Its rugged cartridge architecture, enhanced containment capability and user‑friendly installation make it an excellent choice wherever equipment uptime, environmental protection and operator safety are top priorities. 

 

Key Features; 

• Available in both metric and inch shaft sizes, ensuring compatibility with international pump standards and diverse OEM specifications. 

• Bi‑directional operation, independent of shaft rotation direction, enabling versatile application across different pump types and variable process conditions. 

• Robust, refurbish-able design supports cost‑effective overhauls by replacing wear components rather than the complete cartridge, reducing life‑cycle sealing costs. 

• Tandem double cartridge mechanical seal providing secondary containment and enhanced leakage control for hazardous, corrosive, abrasive and volatile process fluids in critical services. 

• Rotating multi‑spring / wave‑spring design maintains stable dynamic performance across a wide range of operating conditions and media, including light slurries and contaminated process fluids. 

• Cartridge construction, factory assembled and tested, supplied as a preset unit to ensure accurate shaft setting, simplified installation, reduced assembly errors and quick removal during maintenance. 

• Provision for flushing and quench connections, allowing integration with API seal support systems such as Plan 52, Plan 53A/B and Plan 54 to enhance cooling, lubrication and containment where required. 

• Hydraulically balanced seal faces with multi‑spring loading deliver uniform face pressure distribution, reduced heat generation and extended seal life under fluctuating pressure, vibration and thermal cycling. 

• Tandem arrangement (Arrangement 2) offers additional safety and back‑up sealing performance, supporting low emissions and improved environmental protection for API process pumps and heavy‑duty rotating equipment. 

 

Service Overview; 

Parameter	Value
Equipment	Process Pumps, API Pumps, Mixers, Agitators, Compressors
Fluid	Hydrocarbons, Chemicals, Solvents, Slurries, Process Fluids
Service Nature	Hazardous, Corrosive, Volatile, High Temperature
Operating Mode	Continuous Industrial Duty

 

Specifications; 

Item	Min	Max	Typical / Notes
Shaft Size	20 mm (0.750”)	300 mm (12.000”)	Larger sizes on request
Pressure	Vacuum	40 bar (580 psi)	Higher pressure variants available
Temperature	-40°C (-40°F)	+220°C (+428°F)	Depends on elastomer selection
Speed	—	3600 RPM	Based on seal size and service
Seal Design	—	—	Tandem Double Cartridge
Spring Arrangement	—	—	Multi-Spring Hydraulically Balanced

 

Materials; 

Component	Standard Material	Optional Material	Comment
Seal Faces	Carbon vs Silicon Carbide	Tungsten Carbide / Silicon Carbide	Service-dependent pairing
Elastomers	FKM (Viton)	EPDM / FFKM / PTFE	Based on chemical compatibility
Metal Parts	SS 316	Duplex SS / Hastelloy / Alloy 20 / Titanium	Corrosion-resistant options
Springs	SS 316	Hastelloy C	Suitable for aggressive fluids

 

Applications; 

• Pulp and paper mills 

• Sugar and distillery plants 

• Steel and mining industries 

• Chemical processing equipment 

• API 610 and ANSI process pumps 

• Food and beverage process systems 

• Power generation and utility services 

• Fertilizer and agrochemical industries 

• Pharmaceutical manufacturing plants 

• Water and wastewater treatment systems 

• Petrochemical and refinery process pumps 

• Hydrocarbon and volatile fluid handling systems 

 

Operating Limits; 

Parameter	Value
Pressure	Up to 40 bar (580 psi)
Temperature	-40°C to +220°C (-40°F to +428°F)
Speed	Up to 3600 RPM
Size Range	20 mm to 300 mm (0.750” to 12.000”)

 

Engineering Note; 

The above values represent typical industrial operating capabilities for tandem double cartridge multi-spring mechanical seals. Final seal selection should consider fluid properties, vapor pressure, shaft deflection, API piping plan requirements, and equipment operating conditions. For critical or hazardous applications, verification of materials, flush plans, and environmental compliance is recommended prior to final selection.