Old version of document. The recommendations in this document cover the construction, testing and operation of diesel engines for use in potentially flammable atmospheres. They address only the hazards that arise from the flammable environment and should be used to supplement existing specifications and safety precautions applicable to engines generally. The Engineering Equipment and Materials Users' Association is a European based organisation, supporting companies that own or operate industrial facilities. Website: www.

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It is an organisation of substantial purchasers and users of engineering products, whose members include leading national and multi-national companies in the petroleum, gas; chemical and energy industries.

A list of Full and Associate Members the latter being limited to membership of three technical committees is given below. EEMUA is concerned with the design, installation, operation and maintenance of the engineering plant used by members in pursuing their business activities.

The Association aims to reduce members' costs by providing the opportunity for them to share resources and expertise in order to keep abreast of technological developments and improve the effectiveness and efficiency of their engineering activities. EEMUA supports the British Standards Institution, works with other institutions, associations, government departments, regulatory authorities and the Confederation of British Industry, and is also actively involved with other standards-making bodies, both national and international, such as the American Petroleum Institute.

Work, which is carried out in-house by members alone or with the help of other organisations, may lead to the production of Association publications. These are prepared primarily for members' use, but are usually offered for sale and thus for more general use.

Such publications may also be submitted, normally through the British Standards Institution, as bases for appropriate national, European or international standards. As the subject dealt with seems likely to be of wide interest, this publication is also being made available for sale to non-members of the Association. Any person who encounters an inaccuracy or ambiguity when making use of this publication is asked to notify EEMUA without delay so that the matter may be investigated and appropriate action taken.

It has been assumed in the preparation of this publication that the user will ensure selection of those parts of its contents appropriate to the intended application and that such selection and application are correctly carried out by appropriately qualified and experienced people for whose guidance the publication has been prepared. EEMUA does not, and indeed cannot, make any representation or give any warranty or guarantee in connection with material contained in its publications, and expressly disclaims any liability or responsibility for damage or loss resulting from their use.

Any recommendations contained herein are based on the most authoritative information available at the time of writing and on good engineering practice, but it is essential for the user to take account of pertinent subsequent developments or legislation. All rights are reserved. No part of this Publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electronic, mechanical, photocopying, recording or other.

Infringing the copyright is not only breaking the law, but also, through reduction in Association's income, jeopardising the availability of future publications. SWix 8ps. The maximum permissable surface temperature shall be the auto-ignition temperature of the explosive atmosphere 2 Delete the second paragraph and Figure 1 Consequently, in Paragraph b on page 39, "figure 3" should be amended to "figure 1"; and on page 40, the title of the figure should be amended to "Figure 1" Please amend your copy of Publication accordingly as soon as possible Chris A Hutchins Technical secretary, on behalf of the EEMUA Machinery committee May 94 A:amd.

On the formation of EEMUA in it was designated EEMUA Publication No This issue draws upon experience in the use of the earlier documents in the petroleum, petrochemical and allied industries, and the recommendations are directed towards those industries.

The previous sub-division into mobile and permanent installations has been discontinued, and the scope has been limited to Zone 2 hazardous area. The recomeridations in this document are related to hardware only and are supplementary io existing safety precautions. Training in the use of diesel engines in hazardous areas is outside the scope of this document. SCOPE The recommendations in this document cover the construction, testing and operation of diesel engines for use in potentially flammable atmospheres.

They address only the hazards. They are applicable to naturally aspirated and turbocharged engines and engines pressure charged by a blower mechanically driven from the engme crankshaft. They cover four-stroke engines and two-stroke engines with fuel injected into the combustion chamber.

Crankcase scavenged engines are not covered. They may be applied to liquid cooled and air cooled engines but the surface temperature limits might render the latter impractical.

The recommendations cover permanent or temporary installarions in Zone 2 areas. Protection of engines in Group IIC gases is not covered. Also, protection of engines for use in atmospheres likely to contain flammables with auto-ignition temperatures below C are not covered. Road tanker vehicles subject to the 'Petroleum Spirit Conveyance by Road Regulations' and the 'Inflammable Substances Conveyance by Road Regulations' are excluded from these recommendations, since the conditions under which they may load or unload at installations and depots are described in the Institute of Petroleum Marketing Safety Codes.

Previous page is blank 3. Previous page is blank 5. The flame-proof enclosure includes all the gas passages associated with the inlet air, the engine combustion chambers and the exhaust gases, between the inlet flame arrester and the exhaust flame arrester assemblies inclusive. Flame-Proof Equipment Supplier The supplier of flame-proof equipment attached to or forming part of an engine. Flame-Proof Joint The place where the surfaces of two parts of a flame-proof enclosure come together and prevent the transmission of an internal explosion to the atmosphere surrounding the enclosure.

Open Joints One where an opening of the joint does not affect the integrity of the flame-proof enclosure. An open joint is not required to be leaktight for the normal operation of the engine. Potentidy Flammable Atmosphere An atmosphere which might contain flammable gases or vapours such as to require special precautions for the construction and use of diesel engines.

It consists of a turbine driven by the exhaust gas, and an impeller, joined by a common shaft Zone 1 A zone in which an explosive gas-air niixture is likely to occur in normal operation see BS Part 1 Zone 2 A zone in which an explosive gas mixture is not likely to occur in normal operation, and if it occurs it will exist only for a short time see BS Part 1.

Alternatively for mobile equipment only, electric starters may be of convention design provided the electrical supply is off-engine and sited such that the starter can be used only in a non-hazardous area. The length and bore dimensions of the cold starting fluid jet shall be proportioned so that the jet is flameproof for substances in apparatus Group IIB. Previous page is blank 9. Fan shrouds shall be of either steel or plastic construction subject to the following limitations; a b Steel shrouds shall not be used in conjunction with light metal alloy blades.

The shroud shall be bonded to the engine. External rotating parts shall be installed such as to provide clearance without contact with fixed parts of the engine, its mountings and equipment, and other nearby objects.

Clearance shall be maintained during normal operation, starting and stopping, and the sudden application or rejection of full load. Drive belts shall satisfy the electrical resistance requirements of IS and IS Previous page is blank The maximum permissible surface temperature shall be determined from figure 1 for the auto-ignition temperature of the explosive atmosphere and the degree of ventilation of the engine hot surfaces see subsections 6.

During operation and during any of the tests described in Appendix B surface temperatures shall not exceed the temperatures determined in figure 1. Maximum Permitted SurfaceTemperature 6. Note 1. Note 2. The type of ventilation shall be that applicable to conditions following shutdown, ie. Shrouding shall be not closer than 75mm to hot surfaces Naturally Ventilated Installations The engine installation shall be designated 'naturally ventilated' if the shrouding round the engine is open at its base and the top is perforated to give an open area not less than iwo of the top surface.

An engine with flame-proof equipment designed and tested for an unventilated or naturally ventilated installation may be used in a forced ventilation installation. This will necessitate adequate strength and the installation of flame arresters and spark arresters. They shall be capable of holding a test pressure with air at 0. Inlets and exhausts on the engine side of turbochargers or engine driven blowers shall be capable of holding a pressure of 2. Note 1: Careful consideration should be given to the procedures for carrying out these pneumatic tests to ensure that there is no danger of injury or damage through failure of the system.

Note 2: Ductwork which is not part of the flameproof equipment manufacturer's supply should be designed and installed to a suitable standard for the conditions in which the engine will operute. It is recommended that the ductu. Previous page is blank Explosion pressure shall be measured as described in Appendix A2. Production systems shall be pressure tested to the values detailed in table 1.

Pressure Tested to Set Values The prototype system shall be subjected to explosion and flame transmission tests in accordance with Appendix Al. Pressure Test for a System Using Detonation Arresters This method oniy applies where detonation arresters which have been tested in accordance with BS are used and where the nominal diameter of the inlet or exhaust system is equal to or smaller than that of the detonation arrester. Hydraulic pressure tests shall be applied without loss of pressure for not less than 10 min.

Test Method a Pressuretestedaccodig to the measured explosion P-. In addition the integrity of the joint shall remain intact, without leakage, for the operational time interval between maintenance requirements for the joint. The manufacturer shall state any conditions which impose a limit upon the joint and provide clear instructions and data for the manner in which the joint is to be serviced at each service interval or at any intervening time when the joint has been disturbed Open Joints Any linear and continuous open path between the flameproof enclosure and the surrounding atmosphere shall be within the dimensions of length versus gap shown in EN BS Part 5 Threaded joints shall comply with table 5 of EN BS Part 5 Screwed fastenings and associated counter-bores shall comply with EN BS Part 51, but need not be shrouded.

When a flexible metallic pipe is used, then either: Extemal surfaces shall not exceed the temperature limits of Clause Flame arresters shall be removable as complete units for inspection, Inlet arresters shall not be interchangeable with exhaust arresters The joint between a flame arrester and the flame-proof enclosure shall be classed as an 'open joint' Flame arrester elements shall: a b Nute: be designed such that they cannot be dismantled; or have stamped on the casing the number of items for correct assembly of the arrester elements.

Option a is theprefeerred option The materials used for the construction of inlet flame arrester elements shall have corrosion resistant properties appropria te for the environment in which the engine will operate The materials used for the construction of exhaust flame arrester elements shaii have corrosion and abrasion resistance properties equal to or better than stainless steel The valve shall close automatically to stop the engine when overspeeding occurs The engine shall not be capable of running when the inlet shut-off valve is closed On installations with a preset governor control such as a generator set or air compressor the fuel supply shall automatically shut off when the air shut-off valve is activated It is permissible for carbon dioxide to be injected into the inlet for emergency shut-down but only in conjunction with a shut-off valve.

No other fire extinguisher fluid shall be injected into the inlet After operation of the shut-off valve it shall remain closed until manually reset The shut-off valve shall also be capable of manual operation. For an attended engine the conto1 shall be in the operator's cab. For an unattended engine the control shall be in a prominent and accessible position outside the engine closure. Note : For large engines, consideration should be given to providing manual controls at a number of locations.

It shall be of a type suitable for the power of the engine, taking into consideration the back pressure imposed on the engine The spark arrester shall prevent the emission of sparks into the surrounding atmosphere.

Testing shall be in accordance The outlet flame arrester shall be tested with ignition in the compressor and at the maximum delivery temperature and pressure and shall comply with the surface temperature requirements of Section 6. The intake shall not be from the air inlet downstream of the inlet shut-off valve.

Note: The use of compressors in potentially hazardous environments should be avoided where possible. The minimum level of dormation is detailed in Appendix C Following successful completion of the testing, the documentation shall be endorsed with the following: 'The equipment to which this drawing refers forms part of equipment complying with the requirements of EEMUA Publication No.

The blanking plate design shall allow the source to be fitted at each port position. Gas input valves, fitted to the blanking plate. Pressure tranducers, fitted to the blanking plate and at other locations described in A. Note: Bis equipment is only necessary if eqdosion pressure tests are being cam'ed out simultaneously with the transmission test.

For group IIB gases test gas cl shall be used. No part of the gas containment material shall be within mm of any gas outlet or joint in the flame-proof enclosure. Assemble the system under test either inlet or exhaust , the gas input valves and the low energy ignition source to the blanking plate.

Flush the systems under test with a minimum of six volumes of test gas. Check the gas conditions, which for the test shall be ambient pressure and a temperature of 20 C 5 C.

Initiate an explosion using the low energy ignition source. Re-establish the correct gas mixture and conditions in the system and repeat the explosion. A minimum of ten explosions shall be made at each ignition position. Pressure tranducers and a pressure recording system are then required in addition to the equipment detailed in A.





PUB 107 Recommendations for the protection of diesel engines for use in zone 2 hazardous areas






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