Substituting a 1" Blake seacock

danielefua

danielefua

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They do not make them anymore!!!! It is the raw water inlet to a 4.108 Perkins. I have two questions:
1) should I fit a Blake of different size, which between 1-1/2" and 3/4"?
2) if I have to stay with a 1" seacock I would like to fit a very good one: marine grade bronze with the flange like the Groco's or the Perko's. In particular these are both difficult to find in Europe. Any idea of a mail order store that stocks them on this side of the pond? ASAP does not stock them.

Thanks
Daniel
 
The flange of the Blake 3/4" seacock is smaller but it is problem I can cope with.
My concern is whether the smaller inlet is still sufficient for cooling a 45HP engine.

The 30 year old seacock needed replacement and, after a difficult dismantling job, cannot be salvaged... I am afraid! :-(

Daniel
 
What about a bronze skin fitting and bronze ball valve or gate valve.

Or even a Marelon seacock!
 
danielefua said:
They do not make them anymore!!!! It is the raw water inlet to a 4.108 Perkins. I have two questions:
1) should I fit a Blake of different size, which between 1-1/2" and 3/4"?
2) if I have to stay with a 1" seacock I would like to fit a very good one: marine grade bronze with the flange like the Groco's or the Perko's. In particular these are both difficult to find in Europe. Any idea of a mail order store that stocks them on this side of the pond? ASAP does not stock them.

Thanks
Daniel
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The 3/4" one will be plenty adequate, but ASAP do supply gunmetal ones with seacocks etc. which will do nicely thankyou!
 
Please notice that the cross section of 3/4" will be proportional to 9/16 of the previous, i.e. close to half. This is quite a bit less and I would like to be positively assured that it will be still enough.
I have been in touch with ASAP and they stock all kind of in-line valves but no bronze seacocks with the internal flange strongly recommended for safety reasons.

Just a curiosity: does anyone know why Blake stopped producing the 1" seacock?

Perko and Groco are from the US and difficult to find in Europe; is there any similar reliable brand available in this part of the world - apart from Blake not applicable for the above reason?

Daniel
 
danielefua said:
Please notice that the cross section of 3/4" will be proportional to 9/16 of the previous, i.e. close to half. This is quite a bit less and I would like to be positively assured that it will be still enough.
I have been in touch with ASAP and they stock all kind of in-line valves but no bronze seacocks with the internal flange strongly recommended for safety reasons.

Just a curiosity: does anyone know why Blake stopped producing the 1" seacock?

Perko and Groco are from the US and difficult to find in Europe; is there any similar reliable brand available in this part of the world - apart from Blake not applicable for the above reason?

Daniel
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Well ASAP are the Perko distributor for the UK so I expect they could order for you. Perko also have a distributor in Italy.

I expect the answer to your question about lack of availablity is lack of demand, probably related (like Blakes) to high prices compared with the perfectly acceptable alternatives. Bronze skin fittings and DZR ball valves are used pretty universally now. If they were unsafe or unreliable there would be lots of boats at the bottom of the sea!

Would like to know the source of the "strong recommendation for safety reasons" of flanged fittings as this is the first time I have ever heard of it (but maybe I am ignorant).
 
Do Not Reduce The Seacock Inlet Inside Diameter

danielefua said:
Please notice that the cross section of 3/4" will be proportional to 9/16 of the previous, i.e. close to half.....
Click to expand...

For the same flow rate (engine rpm) if you half the inlet area you will significantly increase the pressure to be overcome at the inlet. Its not a linear relationship. Pressure Loss = Flow Rate Sqrd / Area Sqrd Note: the formula is not complete by far, there are other factors such as density and coefficients involved, but you get the drift if you do some simple arithmetic.

I would recommend that you stick with the same inlet size or larger. Going small on diameter where flow is critical is never a good idea.

Unless you know how the engineer designed the cooling system you cant just assume it will be OK.

Que contrary posts claiming you can - if it was my boat I would not risk my engine through premature impeller wear or a choked (throttled) coolant flow.
 
I agree with both Tranona and Blowingoldboots. I would use a conventional skin fitting and DZR ball valve, one inch bore, taking the supply to a Vetus strainer. That's what I did with mine (except I went from 1/2 up to 3/4 inch) quite a few years ago, no problems and better engine performance.
 
Threads and Flanges

Tranona said:
... Would like to know the source of the "strong recommendation for safety reasons" of flanged fittings as this is the first time I have ever heard of it (but maybe I am ignorant).
Click to expand...

Its to do with fitting valves onto threaded connections. The threads can be damaged and are considered weak points. You can also screw a tapered pipe thread onto a parallel (straight)l pipe thread and think you have got a strong fitting which you would not have. I think the thread designations are NPT and NPS.

Like anything if the connection is selected correctly and threads are made up properly, there should not be a risk.

In my industry NPT has been the result of so many fatalities that they are banned on high pressure systems in many Companies.
 
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BlowingOldBoots said:
Like anything if the connection is selected correctly and threads are made up properly, there should not be a risk.

But in reality the ones that ASAP (and any other reputable marine supplier) offers will be correct and are pretty idiot proof to instal - and no high pressures involved.

BTW I have scary memories of the bolts on my flanged fittings when I bought the boat 30 years ago. When I checked them every one crumbled away as soon as I put a spanner on the nuts!. Fortunately the sealant was well stuck!
Click to expand...
Click to expand...
 
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