centrifugal pump/strainer issue

[Nick_H]

A bit PBO'ish this one.

I have a raw water cooling loop with a centrifugal pump. Problem is if I place the strainer above water level, which is nice from a safety point of view, the pump wont self prime. If I place it below water level, the pump obviously primes OK but I have two more hose connections below water level, which isn't good practice. Also, as most of the loop is then above the strainer, when I open it to clean the gauze it empties a couple of litres of sea water into the bilge, though in the med it seldom needs cleaning, so this isn't a big issue.

Currently I have a cheapo plastic strainer, which I have no intention of keeping, so what's the best solution, buy a quality bronze strainer with solid lid and site it below water level, or buy a different type of pump that self primes. If the latter, then any suggestion on the type of pump, as it needs to be continuous duty, and much better if it can run dry without damage.

Alternatively, is one of these the answer, fitted directly to the seacock?

The top would probably still be below water level, so it doesn't achieve its intended purpose of being able to clean the gauze without closing the sea cock, but at least it would mean two less hose connections?

 

[DAKA]

Sorry Nick, I dont know the answer but I do have 3 x seacocks like the ones you picture on my air con and they are horrid things, lids get stuck, whole thing unscrews as you attempt the biggest hammer you can find and eventually after a few weeks and several attempts it gives up and lets you get to the strainer and you find it clear anyway !

Suggest clear lid type.

 

[jfm]

Nick, on all mine where the pump is centrifugal (and therefore won't prime) I have the ones in your picture and yes you have to shut the seacock to clean the strainer but that is no hardship. On a couple, where space allows, the top of the strainer has been placed just above sealevel but that is no great shakes really and the ones that are below w/line are fine

Given that you want the pump to run continuouslty a centrifugal pump makes good sense so I'd go with the strianer in the pic and stuff it below the waterline; job done

 

[Nick_H]

Sorted, if Fairline use them as std then clearly they're fit for purpose. Sounds like the top thread needs a bit of copper slip when it's put back on to stop the problems Daka has experienced.

 

[jfm]

Sorted, if Fairline use them as std then clearly they're fit for purpose. Sounds like the top thread needs a bit of copper slip when it's put back on to stop the problems Daka has experienced.

I've honestly never had the problem Daka reports. I just grease the thread of the cap and probably open them 3 times/year which is enough exercise. Also you want the body screwed hard into the seacock maybe on an adhesive thread sealant (Loctite do one; borrow my tube) so the body doesn't rotate all the time when you remove the cap

 

[DAKA]

Happy to accept jfm's arguments.
Mine only get undone once a year when its time to antifreeze.

I'll try a bit of grease next year.

When they are stuck, I find an old style chain oil filter remover best.