21 replies to this topic

[tynor]

At my last race, i noticed my shirt did not cool down as quickly as usual.  The pump itself seems healthy - when I disconnect from the feed, it pumps a good volume of water through its outlet.  I suspect some sort of flow related problem (in the shirt?) since the amount of water returning to the cooler is just a trickle - and I recall seeing a stronger stream when I first bought the system.

 

I measure approx 250 ml/minute (~3.3 gallons/hour) flow rate coming back from the shirt.  I bought a replacement pump (a 360gph Rule bilge pump - exact replacement) and see no difference in flow rate.

 

I had never actually measured the flow rate when working normally.  Can anyone advise what a normal amount of flow coming back into the cooler?   Advice about other troubleshooting I can do?

 

 

 

[Steve Scheifler]

Best Answer

Unrestricted flow rate is only half the equation, you also need sufficient pressure. Since you replaced the pump, I would look for kinks in the lines including shirt, and maybe run a mild bleach mixture through the entire system for 15min in case there is mildew or the like clogging it. Also check wiring to be certain that it is getting full voltage and can handle some current. Does the pump get hot?

[callumhay]

If you have not done so already, check the o rings and plastic connections for fit/tightness. These are wear areas especially if you disconnect frequently.

[Bench Racer]

After a couple tough lessons, I now plug in cool shirt, flip the cooler switch on before strapping in. Those couple lessons were called a kink/sharp bend in the shirt tube and minimal flow equals minimal cooling. Make sure the shirt tube doesn't have a permanent kink in the tube. 

[tynor]

Thanks for the ideas.   I've run some bleach through the system and inspected for obvious kinks/bends in the shirt and hoses.  Nothing obvious...

 

O-rings look fine.  Connections are tight.  No leaks.

 

It might well be that this flow rate is "normal" - and the lack of cooling i thought I detected was just subjective.   I've sent a query to coolshirt support to see if they can give me an expected flow rate for a properly functioning pump and shirt...

[tynor]

Actually -- I believe the bleach flush did the trick.  I remeasured flow rate after a 15 minute flush and letting the bleach sit in the hose/shirt for a few hours.   Much improved flow!   I now see about 11 gal/hour -- a 3x improvement.

 

Thanks Steve Scheifler for the idea.  I think I need to make this part of my normal routine -- a bleach flush is not just an off-season checklist item - I'll be doing it more frequently.

 

For posterity, I took a video to show what 11 gal/hour looks like at the return hose:

 

[Johnny D]

Mine's home made and I have the pump from Walmart so it may not be the case.

 

If I drain too much water out, I have to turn/rotate the pump sideways a bit it get it primed or de-buggered but my intake is on the bottom.

You hear it when it starts to work well.

 

J~

[tynor]

Coolshirt.com support confirmed that 11 gph is "normal" flow rate in case anyone hits this thread with similar problems.

[Johnny D]

https://www.walmart....-12VDC/11071178

 

J~

[Johnny D]

https://www.walmart....-12VDC/11071178

 

J~

 

Sorry, a bit to much, how about this one.

 

Still way more

https://www.walmart....V2WFcQAb8aL_8ew

[SaulSpeedwell]

WHERE DOES IT SAY IN THE GCR THAT YOU CAN BLUEPRINT YOUR COOL-SUIT?!?!?! 

 

-Ghost of Jim Boemler

[Steve Scheifler]

Sorry, a bit to much, how about this one.

Still way more
https://www.walmart....V2WFcQAb8aL_8ew

Why do you want more? The common ones seem to do quite well. Even if a litte more might be good you don't need *that* much. Too much more may not work as well and may also be too much pressure for lines and fittings. Just pumping it that much faster alone will add heat to it. You want the water to flow at a rate (speed actually) that allows heat to trasfer to it but not so slowly that it's warm before exiting the shirt. A bit like correctly matching a radiator and water pump to an engine, bigger tubes and higher volume pump aren't necessarily better.

[Johnny D]

Why do you want more? The common ones seem to do quite well. Even a litte more might be good you don't need that much. Too much more may not work as well and may also be too much pressure for lines and fittings. Just pumping it that much faster alone will add hest to it. You want the water to flow at a rate (speed actually) that allows heat to trasfer to it but not so slowly that it's warm before exiting the shirt. A bit like correctly matching a radiator and water pump to an engine, bigger tubes and higher volume pump aren't necessarily better.

I just built it to the diy BOM, beside the prime from time to time it works great for years.

Why don't you want more? Is his ^ 11 GPH really working or he's just having a issue?

[Steve Scheifler]

Sorry for the typos. Left out "if" when saying even if a little more might be good.. Point being if 11 gph is close then you probably don't want hundreds. A lot of systems out there running from ne on pumps like his, though I admit it is a bit lower that I'd guessed from draining ours. I also typed hest rather than heat. That unnecessary work and energy use is itself adding heat to the water. I don't think it makes sense to increase flow by orders of magnitude just because you can.

[Danny Steyn]

I have played with higher flow rate pumps in the hope I would increase the cooling.

Well it works for about 30 seconds, and then it really cools you down as you sit in several gallons of ice cold wafter freezing your nuts off when the glued joints if your coolshirt fail.

Trust me on this, 11 gallons per minute is near the upper limit on the current coolshirts, or the back pressure will cause the joints to fail.

[SaulSpeedwell]

Why do you want more? The common ones seem to do quite well. Even if a litte more might be good you don't need *that* much. Too much more may not work as well and may also be too much pressure for lines and fittings. Just pumping it that much faster alone will add heat to it. You want the water to flow at a rate (speed actually) that allows heat to trasfer to it but not so slowly that it's warm before exiting the shirt. A bit like correctly matching a radiator and water pump to an engine, bigger tubes and higher volume pump aren't necessarily better.

Right.  That is why boiler systems flow at a prescribed rate that isn't particularly speedy, and why our Miatas run coolest with a "restrictor plate" (i.e. gutted thermostat) versus no thermostat.  

 

With air cooling, more airspeed is almost always better - although sometimes unintended consequences result.  "According to sources inside the administration", a well-known kidnapper van design from the 1990s was found to reach a stagnant equilibrium of approximately zero airflow in the engine bay when driven at highway speeds.  After the styling department got done with the front end refresh, it turns out the grill opening was too LARGE for the ability of the engine bay/bellypan to evacuate the incoming pressure.  With zero pressure on either side of the radiator, zero air flow was taking place.  The solution was ... SURPRISE! ... a smaller grill opening.   Higher pressure in front of the radiator resulted in more flow THROUGH the radiator towards the low pressure area left over by the bellypan outlet area, and thus people could be more reliably kidnapped over long distances in hot weather, just like before the styling department went TIHSEPA. 

 

But with liquid-liquid heat exchangers (oil coolers ... outboard boat motors that cool from lake/Ocean water .... and, well, Cool-Suits, sort of?), the rate of flow has to be balanced correctly.  If nothing else, you don't want cavitation that results in transferring heat with the efficiency of air instead of the efficiency of water.  If you feel like demonstrating this to yourself, put one hand in 212F air and the other hand in 212F water.  Report back with a YouTube vid

[SaulSpeedwell]

I have played with higher flow rate pumps in the hope I would increase the cooling.

Well it works for about 30 seconds, and then it really cools you down as you sit in several gallons of ice cold wafter freezing your nuts off when the glued joints if your coolshirt fail.

Trust me on this, 11 gallons per minute is near the upper limit on the current coolshirts, or the back pressure will cause the joints to fail.

 

I've honestly wondered if a direct liquid drip ice water system would be superior to the closed "conduction"-based Cool-Suit.  Drip ice cold water into your suit (and into your gullet) at the rate you prefer?  Our former friend and foe, Harry Manning (RIP), was a proponent of using recyclable ice packs in his suit to help him stay cool.  I wasn't that keen on having frozen bricks strapped into my personal crumple zone. 

[Johnny D]

So I'm sure the guy building his own was like "oh cool a 12v pump at Walmart for $15 bucks.

Interesting, I could do a pot and turn it way down and flow meter for the sweet spot.
The pump has a 3/4 outlet that's reduced to the tube size. Not pressized so the GPH may drop.
I haven't had any cool shirt joint popping/breakage. The quick disconnects I'm sure are rated much higher, the tube itself is rated way up there.

I'm pretty sure if you drop the water it will warm and you'll be hot. Need the flow into contact and out.

As for air I've always wondered if you could do a "swamp cooler" in you're ice chest with a drip screen system,

[Steve Scheifler]

Prior to this recent return we had never used cool suits. Tom used the ice pack vest a few times which seemed much better than nothing but a bit of a hassle. When was really hot I simply soaked the front and arms of my suit from the cooler then dunked my balaclava just before putting it on. It was effective enough for our relatively short sessions and was especially helpful if we were delayed on grid when a prod car oiled the track or spec wreckers had to be dragged in. Of course with the evaporative approach you need to account for an extra few pounds lost, but better from your suit than your body.

[luvin_the_rings]

is it the common house detergents or the water that damages the Nomex's ability to keep from igniting?