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EP Type-2

Double Mechanical Seal With an Elastomer Drive

The MECO EP Type-2 model is used in many sealing applications with low to medium-high shaft speeds, on small to large shaft diameters. The configuration is a double mechanical seal using an elastomer drive to rotate bearing-grade, synthetic seal faces against fixed, hardened stainless steel seal faces. The EP Type-2 uses full-contact, soft-face mechanical shaft sealing technology, sized for OEM and existing in-house process equipment. The EP Type-2 model provides the superior performance, durability and quality of workmanship that are hallmarks of MECO’s many other highly-regarded seals. MECO’s first-rate customer service is provided for every EP Type-2 seal.

What is MECO’s EP Type-2 Seal?

The MECO EP Type-2 model is appropriate for many sealing applications with low to medium-high shaft speeds, on small to large shaft diameters. It is a full-contact, soft-face double mechanical seal using an elastomer drive to rotate bearing-grade, synthetic seal faces against fixed, stainless steel seal faces. The EP Type-2 seal requires a compressed air or inert gas purge.

When are EP Type-2 Seals the Best Option?

The MECO EP Type-2 seal is ideal for single- or twin-shafted extruder-compounders, plow blenders, paddle blenders, conveyors and similar rotating equipment used in the plastics, chemical, metals, pharmaceutical, food and other process industries. The EP Type-2 seal model is fully-split and typically frequently used on polymer extruders containing particulates and vapors. They are well-suited for hard-to-access equipment and machinery with set speeds and feed rates. The seal is appropriate for vacuum service, low pressures and steady-state applications that experience infrequent thermal expansion or pressure changes. In contrast, the MECO Model EP Type-3 seal can be a better match for challenging applications with frequent thermal cycles, pressure cycles and/or aggressive chemicals.

How does the EP Type-2 Seal model work?

The MECO EP Type-2 seal model features a precision-machined, split seal housing similar to a stuffing box and gland follower. The elastomer drive has two rotating seal faces and a drive elastomer. The elastomer and rotors interlock, forming an airtight and watertight seal. The low-friction rotating seal faces are at right angles to the shaft and in full contact with the stationary seal faces. These rotating parts are fitted around the shaft before the seal housing is installed.

The nose or pilot of the gland follower provides the outboard (secondary) stationary seal face. A plate attached to the bottom of the stuffing box provides the inboard (primary) stationary seal face. These are precision machined stationary seal faces (stators) with lapped and polished seal surfaces. The seal cavity is charged with low-pressure air or an inert gas, which acts as a barrier fluid to provide pneumatic seal face loading.

How is the EP Type-2 Seal model maintained?

The MECO EP Type 2 seal model is pneumatically-loaded to provide seal face pressure, with the air/gas also functioning as a diagnostic tool. A pressure gauge is attached to the seal housing to monitor seal cavity pressure. External springs attached to the back of the gland maintain seal face pressure and provide alignment.

As the sacrificial rotor material wears, the springs gradually expand and the seal cavity pressure gradually decreases. After a significant pressure decrease or when an opportunity presents itself, the springs should be re-set. The pressure will then reset itself.

What Sizes Are Available?

The MECO EP Type-2 seal model is custom-designed and built to order. Typical assemblies are fully split and often are made for twin shafts. Shaft diameters range from 1" (25mm) to 20" (500mm) and include any size in between. Dimensions vary according to the application, but typical dimensions are shown in the illustration below. EP Type-2 seals are readily designed to fit most OEM mounting arrangements and are designer-friendly, to interface with customized in-house process equipment requirements. Seals can be built either to SAE or metric dimensions. Non-removable stuffing boxes, integral to the equipment, can be modified or machined to fit the seal as shown in examples 1 and 2.

What Construction Is Available?

The MECO EP Type-2 seal’s rugged components are designed for long life. The standard assembly uses stainless steel stators. A replaceable stator is available for very large shafts or highly abrasive process materials. The housing is available in various 300-series stainless steels, aluminum, or other corrosion-resistant alloys.

Rotor materials comprise a variety of filled PTFE, PEEK and PBT compounds, chosen for process compatibility. Elastomers are often white silicone; Viton®, EPDM and nitrile are available as alternatives. FDA-compliant versions of the elastomers are available.

Other materials can be used if required and commercially available.

Specifications

Mechanical Capabilities
TEMPERATURE	-60° to 300° F (-50° to 150° C)
PRESSURE	Vacuum to 20 psig (135 kPa)
Shaft Speed	To 375 RPM
Total Indicator Runout (TIR)	1/4" (6mm) standard - greater runout can be accommodated
Repeated Axial Shaft Motion	1/128" (0.2mm)
Thermal Shaft Growth	Limits set per application

Results may vary with operating conditions - please call for discussion.

Literature

EP Type2 Seal

The MECO EP Type-2 model is the best choice for many sealing applications with low to medium-high shaft speeds, on small to large shaft diameters

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Custom Shaft Seals for Plastics Processing

MECO seals offer plastics manufacturers effective, reliable shaft sealing for a wide variety of machinery handling difficult-to-seal products