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MAN B&W Diesel A/S: Service Letter

1) MAN B&W Diesel A/S issued a service letter recommending removal of shields mounted on or around crankcase relief valves as tests showed they negatively impacted the effectiveness of flame arresters. 2) During tests, shields were found to disrupt the functioning of flame arresters, allowing external ignition when tested with both small and large shields. 3) The letter recommends checking engines for shields on relief valves and removing them as soon as possible.

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194 views2 pages

MAN B&W Diesel A/S: Service Letter

1) MAN B&W Diesel A/S issued a service letter recommending removal of shields mounted on or around crankcase relief valves as tests showed they negatively impacted the effectiveness of flame arresters. 2) During tests, shields were found to disrupt the functioning of flame arresters, allowing external ignition when tested with both small and large shields. 3) The letter recommends checking engines for shields on relief valves and removing them as soon as possible.

Uploaded by

KaushalKishore
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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MAN B&W Diesel A/S

Service Letter SL03-420/ERO


February 2003

Crankcase Relief Valves


Action Code: AT FIRST OPPORTUNITY

Dear Sirs

We refer to our Service Letter SL99-373/ERO dated October 1999, outlining our
requirements for crankcase relief valves, which requirements have contributed to
increased safety for crew and ships.

However, it has recently been brought to our attention that some ships in service have
shields mounted on or around the crankcase relief valves. An example is shown in
Fig. 1.

Shields

Fig.1: Shields fitted around crankcase relief valves


HEAD OFFICE (& Postal address) DIESEL SERVICE PRODUCTION FORWARDING MAN B&W Diesel A/S
Teglholmsgade 41 Teglholmsgade 41 Teglholmsgade 35 Teglholmsgade 35 Denmark
DK-2450 Copenhagen SV DK-2450 Copenhagen SV DK-2450 Copenhagen SV DK-2450 Copenhagen SV CVR.No.: 39 66 13 14
Telephone: +45 33 85 11 00 Telephone: +45 33 85 11 00 Telephone: +45 33 85 11 00 Telephone: +45 33 85 11 00
Telex: 16592 manbw dk Telex: 31197 manbw dk Telex: 19023 manfw dk Telex: 19023 manfw dk
Telefax: +45 33 85 10 30 Telefax: +45 33 85 10 49 Telex: 19042 manfw dk Telex: 19042 manfw dk
E-mail: manbw@manbw.dk E-mail: diesel-service@manbw.dk Telefax: +45 33 85 10 17 Telefax: +45 33 85 10 16
http://www.manbw.dk E-mail: manufacturing/copenhagen@manbw.dk
2

We strongly advise against the use of such shields as they will have a negative effect.
The oil mist will still move towards the turbocharger(s) anyway and, even worse, the
shielding will spoil the effect of an, otherwise, well-functioning flame arrester.

During tests made for MAN B&W Diesel by a test institute it was experienced that
when a relief valve with a well-functioning flame arrester was equipped with a shield,
the functioning of the flame arrester was influenced so that external ignition was
experienced when testing with both a small and a large shield.

Fig. 2: Large, small and no shield

Based on this experience, we recommend that you check the relief valves on your
engines and if equipped with such shields, we recommend that these be removed as
soon as possible.

Questions or comments regarding this SL should be directed to our Dept. 2002.

Yours faithfully
MAN B&W Diesel A/S

Carl-Erik Egeberg Erik Ohlsen

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