Water cooled machines - Flow switch VS Pressure differential

[MetFreak]

Hi,
What is the advantages of using one or the other way to make sure you have appropriate cooling.

Choice A : Flow switch for minimum coolant flow
Choice B : Minimum pressure differential between inlet and outlet of the machine

I guess I need to jump back in my Heat Transfer theory ... ?

Thank you !

 

[byrdj]

for Utility Generator's stator cooling water, they use BOTH,

given the discharge is at atmospheric (back to vented tank) only the supply pressure is used for alarm/trip.
an orificed dP flow meter is used in OR logic (1oo2). With a known clean system, the flow is adjusted to alarm/trip values to determine the corresponding inlet pressure for its settings.

I could see where flow restictions could cause the inlet pressure to stay normal as the actual flow decreased.
if there was a leak, the flow would stay normal, but inlet pressure decay

 

[btrueblood]

What happens with debris clogging the flow passages for choice B? Alternatively, what happens to the paddle type sensor if stringy debris hangs it up and gives false indication of flow? What are you trying to cool, and is there a temperature you could measure to verify adequate cooling is occurring? A good system would use both types of sensor (temperature and flow), and fail (cause shutdown) if either parameter is out of limits.

 

[drawoh]

MetFreak,

How do you anticipate your machine failing?

--
JHG

 

[MikeHalloran]

In big yachts, where for example a connecting rod for a 4l/cyl engine costs $10k, they may use all three technologies, alarming on pressure, flow, and temperature, and they might even double up on them, too.

If you're running small junkyard engines and have an unlimited supply and can swap them fast, you might just run the bitch till she breaks, and then install another one.




Mike Halloran
Pembroke Pines, FL, USA

 

[MintJulep]

If the water coming in is too hot neither will tell you that.

 

[BUGGAR]

Do you have to measure the heat by measuring the flow?

 

[EdStainless]

We had high powered electronics that were water cooled.
There were both flow switches right before each power element and a temp sensor connected to each element. We didn't care why the water was hot, it would trip anyway.
But there was this pair at each critical location.

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P.E. Metallurgy, Plymouth Tube