Meeting emission legislation requirements with today’s advanced technology mechanical seal systems

(ESA Publication N^o. 005/95, published November ’95)

This document has been prepared by the Mechanical Seals Division of the ESA for use by original equipment manufacturers, engineering contractors and end users in the process industries , to provide information and guidance on :

	performance of the latest generation of mechanical seals
	application recommendations
	achievement of environmental legislative requirements

Seal manufacturers have responded to market and legislative pressure by developing extremely low- and zero-emission seals. Increased seal life of 3+ years has been reliably attained with low emission single seals and dual seals. These results have been obtained through the use of improved designs, high quality face materials, attention to manufacturing and assembly details, and enhanced seal chamber environment. These advances in seal technology go hand in hand with improved installation, maintenance and operating procedures, to enable considerable reductions in fugitive emissions, and hence substantial savings for the operator.

There is a tangible correlation between low emission and the level of sophistication of the seal technology applied. Those manufacturers with access to more advanced technology are able to provide products with generally higher performance levels.

Most of today’s single mechanical seals, using modern materials and advanced technology, are performing reliably with emissions typically below 1g/h under normal operating conditions in the field. These single mechanical seals are accepted by the US EPA as "the cost effective solution in controlling emissions".

Emission from today’s dual mechanical seals with barrier fluids is essentially zero, usually described as "not measurable with existing instrument technology". These seal arrangements can provide very tight emission control, meeting the requirements of the most stringent environmental legislation across the World.

These performance levels have been supported by independent users over extended periods of operation in the field.

Contents

Executive Summary

Introduction

Emission Legislation

Sealing Technology - the "State-of-the-art"

- Single Mechanical Seals

- Dual Mechanical Seals

- "Sealless" Systems

Application Guide

- Applications suitable for Single Seals

- Applications suitable for Dual Unpressurised (Tandem) Seals

- Applications suitable for Dual Pressurised (Double) Seals

- Applications suitable for "Sealless" Systems

Best Practice for Reliable Sealing Performance

Compliance with Legislation in Practice

Emission Measurement Methods

- EPA Method 21

- Bagging Method

- Flushing Method

List of References

ESA Publication N^o. 005/95, November, 1995. 13 pages. This is the English language version.

The publication is also available in French and German language versions, respectively;

        Comment satisfaire les exigences de la législation sur les émissions par l’utilisation de Garnitures Mécaniques de la technologie avancée

        Erfüllung der Bestimmungen der Emissionsgesetzgebung durch moderne Gleitringdichtungenstechnologie

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