centrifugal pump q.

[Nick_H]

I have two centrifugal pumps feeding raw water cooling circuits, one for the air-con, the other for the gyro. One is US built (Oberdorfer pump with Dayton motor), the other Italian (CEM pump and motor), but both look similar and are 220-240V 50 hz, 1/2hp, 2,800 rpm, continuous duty, with bronze pump body and impeller, and 316 shaft. Does that mean they're definitely interchangeable, or are there any other factors that also need to be the same?

I want to carry spares as life on board is far less comfortable without the gyro and air-con, and i'm thinking I only need one.

Also, the gyro cooling pump has failed twice in 5 years, whereas the air-con pump is still going strong after 12 years. The gyro eats pencil anodes, so i'm wondering if the pumps are being damaged by electrolytic corrosion. The installer has recommended a fresh water flush system is added to the cooling loop, which sounds a good idea. Am I right in thinking that flushing will stop any electrolytic action whilst the gyro is not in use?

Finally, any recommendations for the best value pump manufacturer?

 

[gordmac]

You could try swapping them over to see if the systems still work ok.

 

[BartW]

I don't know about their value / quality
but I have a good source for CEM pumps,

www.ceresoli.net is a dealer to the boat builders in Fiumicino region,
(I have a customer account and good prices)

I never bought Cem from them, but they are in their catalog.

 

[kashurst]

sounds like the pumps are very physically similar on the outside, but what flow rate do they give ? can you find out from the respective manufacturers websites?
if you flush the cooling system(s) with fresh water that will slow down the galvanic action dramatically. Need to check though that the anodes don't form a hard zinc oxide coating on them whilst in fresh water that will stop them working when sea water is running again. Or is there a seawater drain on the seakeeper cooler- just dump it whilst the boat isn't in use. Or you could possible use aluminium alloy anodes instead - but better check with seakeeper what the intercooler core is made from. They may be able to explain why its eating anodes.

 

[jfm]

Yup the pumps sound interchangeable but worthwhile checking flowrate on websites if you can. But if they are physically very similar pumps, and motors have same ratings, they are going to be very close

I recently bought a couple of pumps from Coastal Rides - ex Fairline or Sunseeker - great price and brand new in tatty boxes

Yep fresh water flush will reduce galvanic action. With pure water there is virtually nil action, but even with hosepipe water you're going to reduce it by say 95%. Med water is very salty so has much higher galvanic action rate than UK or US waters, ie what Seakeeper will be used to. You could buy an electric Y valve to introduce the freshwater and have a hosepipe plug in point somewhere on the aft deck, to make the flushing job really easy. Another alternative is fit a bigger anode or additional anodes, if there's space

 

[Nick_H]

Thanks all. I'll check the flow rates at different heads, and if they're similar I'll order one pump as spare as they're very unlikely to both fail during the same holiday.

I've told the supplier to go ahead with the fresh water flush, and try to keep the diverter valve operable by just lifting the laz hatch and using a boat hook or purpose designed linkage, rather than fit an electric valve.

 

[Portofino]

I would pop along to Lyvio marine ( 4 Rue Frederic Mistral Antibes ) I suspects you know where know it is
Having been a SoF boater for a few years .
See what they have ? It's on the LHS as you walk in -pumps .
Having said that'
Google" Calpeda Pumps " and drill down to a bronze esq - ok none corrosive version as opposed to to a base metal bogo that if i understand your post is what you are worried about ? That could be used to pump a food substrate around in a Mr Kippling cake Factory - With this I think it's ok to leave sea water in -
I have one none crrosive with my AC -Sw pump

 

[Nick_H]

Yep, Lyvio are a good outfit and I've used them many times, but they're expensive and this is just for back-up so I can shop around.

I very nearly bought a Calpeda pump yesterday which looked the same spec as my existing pumps, but I found that at this size they have bronze housings but brass impellers, whereas others are all bronze. That's why I asked the question above, because it's clear not all pumps are made the same.