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good day, I am a marine engineer

good day, I am a marine engineer

(OP)
good day,

I am a marine engineer by profession and I wish to hear your opinion.

My vessel sometimes sails on rivers and as a result of muddy water being sucked by my pumps, there are incidents that the mechanical seal wears and my pump starts leaking. I have been reading posts about flushing and I just want to be sure if modifying the line arrangements by introducing distilled water for flushing the stuffing box would really work. As I have read, stuffing box pressure is slightly higher than the suction pressure and introducing a flushing liquid( which is 1 bar higher at 4-8L per hour) would keep the mud from reaching my mechanical seals.

Attached is my pump drawing. I hope you can shed me more enlightenment.

9-:

RE: good day, I am a marine engineer

Good day to you sir. It is a bit late in the evening for me and not able to provide full comment, but I would first ask why you have mechanical seals on this pump at all. On a water service? I would much prefer packing which is more durable and much cheaper to replace. With a good water flush from discharge, packing would be my choice. Mechanical seals may be the most over-applied device since divining rods.

RE: good day, I am a marine engineer

DubMac:I would agree, if the product is expensive or dangerous use much seals.
In this case the flush water could be poor quality (when in the river) but packed gland with flush water cleaning cyclone prior to the stuffing box would be my suggestion.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: good day, I am a marine engineer

Adding to previous post, if you want to maintain the mech. seal arrangement, you could incorporate an inline cyclone to a seal flush arrangement.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: good day, I am a marine engineer

I can't add much more other than at present your flushing line is taken direct off the discharge casing so the current pressure flush might be quite high unless there is a little throttling valve we can't see.

dirty silty water is an issue and for those situations getting clean water to your seal flushes isn't easy even using cyclones on the seal lines or fine filters (which then block up).

You really need to find out which seals you have installed and go onto the seal vendors website or call one of the tech engineers there to get the full information you need on pressures, flows etc.

I'm not sure what the mysterious O ring is doing for you (item 110) - seems to be in the middle of no where.

Clean water ( distilled is a bit OTT) would be better as the seal line also lubricates and flushes the bottom bearing.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: good day, I am a marine engineer

In ships it mostly mechanical seals in all pumps. I myself in a marine engineer. I have not come across gland packing if i can remember right

RE: good day, I am a marine engineer

a lesser micron filter in the suction side and cleaning the same in regular basis can solve the problem i think.

RE: good day, I am a marine engineer

(OP)
I must agree that having packing on the glands would be simpler if you transit to rivers or muddy waters. For the non-seaman, ship owners tend to prefer having mechanical seal on their pumps to have them almost leak free. However, ships don't just sail the open sea. From time to time, they may enter rivers or be berthed on shallow waters. It is a bit out of my powers to have the mechanical seal be replaced by gland packing so my dilemma lead me to just find a way to lessen damaging my mechanical seals before my contract expires. Do you think my initial plan of making fresh water flushing connection would work? If it does? How much pressure should I have the flushing water be delivered and at what rate? Please feel free to give suggestions for other options. Thanks

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