How do I check if disused pump is working?

[CCinAus]

We bought a house with a pool this year, but the pool was bright green with duckweed and the amount of leaves and branches on the bottom was unbelievable (trees were overhanging on every side and some actually had branches dragging in the water). We have now cut back the surrounding trees and spent days scooping out duckweed, leaves and branches. Guesses about when the pool was last used range from 10 to 20 years so the chance of any pool equipment functioning is probably small.

Due to the 10 year drought where I am in Australia water restrictions make emptying and refilling the pool a costly last resort.

We are up to trying to get the thick layer of sludge off the bottom and I'm trying to figure out how I check if the pump is working. I know it's unlikely but it's worth a try. I'm not sure how to go about it, especially as I'm worried the debris remaining in the pool might damage something (I think I need to get a basket for the skimmer as I can't see one in there - is it important to do this first?).

Apologies for my complete lack of knowledge - I'm trying to upskill at pool school but it's hard to know where to start when there is so much wrong!

Thanks for any help!

 

[vln]

Would really help if you can post pictures of the filter setup, it is extremely hard to guide someone blind.

 

[Guest]

Is it set up with a time clock or a controller? Just turn it on with what you have and see if it fires. It won't burn up if you let it run for a minute without water.

 

[CCinAus]

Here are some pics of pump and filter.

Thanks for replies so far!

 

[Bama Rambler]

Just fill the strainer basket with water and fire it up. As Bruce said, it won't hurt it to run a minute without water.

 

[vln]

Make sure the big handle on top of the DAVY filter is on either recirculate or filter.

Could you show some pics of the pool?

 

[CCinAus]

Here are some pictures of the "pool" as requested

 

[4JawChuck]

For God sakes don't run it without water, get a bucket full and take the strainer top off and fill the basket...takes two seconds!

If I had a dollar for every person who brought me a pump with a ruined mechanical seal who said to me "I only ran it for a minute to check the rotation?" I would be a rich man.

EDIT: You posted pics just as I was posting, clean that pool out before you try to recirculate it...you will save yourself a lot of time backflushing the gunk out of the filter. Looks like you need to start with a rake and work your way down to a sieve, that looks nasty!

 

[Guest]

You guys need better pumps, Chuck We "dry fire" almost everything, and running without water for a short period does no damage in that amount of time.

I'd question the time frame you're given by these folks. Reminds of the "I only had two beers, officer" stories :lol:

 

[CCinAus]

Thanks everyone for your input so far - I'll try to let you know how it goes.

 

[4JawChuck]

You guys need better pumps, Chuck We "dry fire" almost everything, and running without water for a short period does no damage in that amount of time.

I'd question the time frame you're given by these folks. Reminds of the "I only had two beers, officer" stories :lol:

A carbon/ceramic mechanical seal is a hydrodynamic bearing, just like the ones in your cars engine...it depends on the fluid media for lubrication and cooling.

Do you often start up your car with no oil in it?

What can cause a mechanical seal to leak or fail?

The loss of the liquid film, or lubricant, between the faces of a mechanical seal is the largest cause of seal failure. This usually results due to a lack of maintenance on the seal’s lubricating parts. Sometimes a seal fails because it wasn’t the right type of mechanical seal for the application. Other causes include improper assembly or installation, cavitation, and improper operation of the pump itself.


What can cause the seal to lose lubrication?

Losing lubrication to the mechanical seal faces can result from a number of factors. Some of these include dry start up, suction loss, plugged flush orifice, increased temperature, the wrong balance, or contamination in the cooler, water jacket, or flush lines.4

http://mechanicalseals4.blogspot.com/

Mechanical seals rarely wear out but are often destroyed in a few seconds of running without lubrication. A perfectly good seal that was working fine before if was left to dry out will often fail if restarted without a sealing film of lubrication because of normal wear of the seal and the resultant abrasive mineral film left from the water that evaporated on the sealing face. Starting a brand new pump dry will shave years off its useful life even though it may not appear to have suffered damage, that soft carbon face starts wearing the millisecond it starts spinning against the unlubricated ceramic seal face.

...besides even if you don't believe me, it take two seconds to dump a litre of water into a pool pump basket sump...it holds enough water to wet the bearing surfaces in the pump.

Why wouldn't you do it?

Easily 50% of the pumps we rebuild that leak from the seal were run dry, some for a few seconds, some for a few minutes when the heat of friction turned the fluid film into vapor and then it ran dry. Another 10% are ones that were "just rebuilt" and the guy who installed it ran it dry before he realized he forgot to open the fluid valves and it started leaking a month after it was installed.

Its poor practice from any practical standpoint, I don't understand why its recommended on this forum...its a huge no-no in every commercial industry I have worked in.

 

[Guest]

You guys need better pumps, Chuck We "dry fire" almost everything, and running without water for a short period does no damage in that amount of time.

I'd question the time frame you're given by these folks. Reminds of the "I only had two beers, officer" stories :lol:

A carbon/ceramic mechanical seal is a hydrodynamic bearing, just like the ones in your cars engine...it depends on the fluid media for lubrication and cooling.

Do you often start up your car with no oil in it?

Every morning It takes a while for the fluid pressure to bring the oil to the upper parts of the engine, so I do truly start every day with no oil!

I'm not suggesting running pumps dry for extended periods of time, but a short while is harmless.

 

[4JawChuck]

Why seals fail.
http://www.maintenanceresources.com/referencelibrary/seals/wsf.htm

(i) Never operate mechanical seals dry. Carefully follow instructions for flushing and cooling connections where specified. Be sure suction and discharge of pump is open and a positive head of fluid is present before starting pump. This applies even to that period when checking for proper direction of rotation and adjustment of motor electrical connections.

Your car engine never starts up dry, it has a lubricating film left from previous operation and it doesn't evaporate like water which will leave an abrasive calcium film behind which also holds the carbon seal face off the seat scoring it. The oil from a cars sump pump takes less than a second to reach operational pressure since it is a positive displacement pump providing cooling and lubrication to the bearings and maintains its prime due to the viscosity of the liquid. The fact that you haven't caused seal failure during your work does not mean you aren't damaging the seal or causing its premature demise. These are facts I have presented, take it for what its worth....or don't.

Its not my pump!

 

[mas985]

I agree with Bruce, running the pump without water for a few seconds shouldn't create any problems. I wouldn't do it a lot or for a long time but I have done once or twice without any ill effects.

Also, a graphite/ceramic seal is under fairly tight compression so the seal doesn't allow any water between the two surfaces anyway. Water surrounds the seal and helps to keep it cool but it really isn't providing any lubrication for the seal, the graphite does that. So the only thing you have to worry about without water is the seal heating up too much but both graphite and ceramic have very high heat tolerance so a few seconds of operation without water should not be a problem at all.

 

[4JawChuck]

Average compression of a carbon ceramic seal spring is about 30 pounds preload pressure, distribute that over the relatively small area of the carbon ring and you have a loading of about 100-150 pds/sq in. This is why the limiting pressure for most unbalanced mechanical seals is 100 pds/sq in, you can run them at higher pressures with compensating liquid pressure behind the seal to apply preload as required.

Mechanical seals work on the principle of a hydrodynamic pressure wedge forming under the carbon seal, the heat of rotation and resultant friction typically turns the water to steam but they require a constant source of cooler water to replenish the lubricant and maintain the seal. Although they appear to be a leak free seal system there is a constant loss of liquid that has turned to vapor escaping from the seal during operation (thats were that light corrosion comes from around a non leaking seal area). One of the hardest mediums to seal is very hot water since the wedge formed is very small, they work best with a running clearance of 1 micron which works out to the clearance achieved with room temperature water...hotter water means less clearance. Different materials are used for other liquids like oil and slurry's to operate correctly under the environmental conditions they are faced with, there are as many different seal material combinations as there are different seal mediums and some seal/material combinations are more tolerant of dry running due to their nature...but not the common carbon/ceramic water seal as you would find in a pool pump.

So although you can spin a brand new seal with no water for a short time the damage you do to the carbon seal and resultant deposited material onto the ceramic fixed seal face will create a slurry of abrasive carbon in the seal zone...which means that until it is flushed out, the carbon ring will wear very quickly. The most often quoted fact of pump repair is that every second of dry running reduces the life of the seal by 10%, that includes the spin down time as well...not just operational speed rpm...and if its a used dried out seal you increase that number by another 10% if it doesn't score on the next run up.

Add the fact that the OP's pump has sat idle and is likely dried out and most certainly has a film of abrasive deposited on the seal ring from evaporation of the seal medium the quick spin of the seal without lubrication could very well finish off a perfectly good seal from scoring...if you had taken the ten seconds it takes to throw some water in the basket it might run for another few years without incident. Spare pumps run only in emergency situations in industry see the same operational risks and the oldest rookie mistake in the book is to spin that emergency pump up dry to check rotation after installation only to find out that once in operation the 10 hr run time seal is now cooked and starts leaking after only a few hours additional runtime.

I just took my pump apart from my pool to replace the bearings (getting noisy) and although the seal is on its 19th year of operation looks fine but approx 1/2 worn, I could likely just put it back into service but since I am already in there its getting replaced. How many times have a I read about a pool pump less than 3 years old already leaking on this forum, how much you want to bet those pumps were run dry at some point or deadheaded or cavitated from lack of prime...all easily rectified issues if all you do is take the time to fill the basket before you fire it up or turn the multiport vale to "test" when you shut it down to maintain the prime.

You guys do know I don't make this stuff up right?

Of course when in doubt consult the mfg's manual for instruction;

IntelliFlo Installation and User’s Guide

Manual Priming and Initial Start-up After Service:

Before a system start-up, the pump and system must be manually primed. Make sure to reopen valves
before operating. To prime IntelliFlo, the strainer pot must be filled with water.
*CAUTION* — DO NOT run the pump dry. If the pump is run dry, the mechanical seal will be damaged and
the pump will start leaking. If this occurs, the damaged seal must be replaced. ALWAYS
maintain proper water level in your pool. Continued operation in this manner could cause
a loss of pressure, resulting in damage to the pump case, impeller and seal.

 

[Bama Rambler]

Ok, the "running the seal dry" part of this thread has been hashed enough by now. It's gotten off topic of the original post so let's let the thread get back on topic or I'm locking it.