Delta P x 2.31 equals head?

GW

Hi Guys,

I have some jobs where I set up taps on the in and out of the pump. Is this the right formula for finding head loss?
Delta P x 2.31 equals head? od is there more to it.

Thanks

Gary





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Bill Nye

Mouse pad

My heatinghelp.com mouse pad says,Pump head rule of thumb: Measure longest run in feet. Allow 6 feet of pump head per 100 feet ( this includes allowance for fittings and boiler)

So yes, it is more a pipe and fitting thing than a what the pump is doing thing.

JimGPE_3

Yep.

If you have the head in PSI, multiplying the PSI by 2.31 gives you the pump head in feet of water column.

2.31 is merely a conversion factor from PSI to feet.

GW

Delta P x 2.31 equals head?

Hi Guys,

I have some jobs where I set up taps on the in and out of the pump. Is this the right formula for finding head loss?
Delta P x 2.31 equals head? od is there more to it.

Thanks

Gary





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GW

sorry- nm

.

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Robert O'Connor_6

if your talking circulators

in a closed loop hydronic system just use what Bill N. wrote.

Don't worry about the pressure of the system . Circulator just has to create differnce in pressure to move water.

Regards,

Robert

Jed_2

Sounds to me like operating point!!!

> in a closed loop hydronic system just use what

> Bill N. wrote.

>

> Don't worry about the pressure

> of the system . Circulator just has to create

> differnce in pressure to move

> water.

>

> Regards,

>

> Robert

Jed_2

Sounds to me like operating point!!!

It's like Bill said, sort of. Wouldn't the differential measurement at the those points yield the operating point of the circulator in that specific circuit? So, it's the intersection of that circuit with that pumps' curve? Not just some SWAG at circuit head.

Jed

bob_25

head

Gary, measure the pressure differential across the pump, it's best to use the same gauge for both measurements and best if both ports are at same elevation. take the diff. in PSI and multiply by 2.31. This is the operating point of the pump in ft. of head and the head loss through the system. If you work with larger circulators that have different size or custom cut impellers, you can check impeller size by closing the valve on the discharge, dead heading the pump. Measure the diff. pressure as before and look at Mfg. pump curve at zero gpm and read impeller size. bob

Jerry Boulanger_2

2.31'/psi is for

water at 60 F, specific gravity 1.0. If the specific gravity is not 1.0, e.g. hot water, glycol, then the conversion factor will change. For water at 200 F, it is 2.41 '/psi. Being out a few feet on a pump with a flat curve can produce a large error in the estimated flow.

Be careful when dead-heading larger pumps to determine impeller diameter. They can heat up very quickly and even explode.

The pump curves produced by manufacturers are not dead accurate. Minor differences in casting finish, etc. in individual pumps can result in deviations from the curve. It's useful only as an estimate of the flow.

GW

so

even if we know the numbers we're still making some guesses I guess.

Does anyone know of a sonic meter that can measure flow w/o cutting into the line?

I've been asking this question for a while now, it seems to be a dream at this point.

Thanks guys,

Gary

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GW

I'm talking a little more than basic

I'm needing actual numbers because I have a large x huge radiant job, manifolds all over. I'll "guess" at a pump(s)see what the pressures are doing, then perhaps put another on in.

Gary

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Weezbo

hmmm...

Large job. 20,000 sq '? 200,000?

GW

well

it's large for me, it's 3 floors of climate panel. About 5000 feet.

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bob_25

density

"Since foot head is a simple energy statement, a pump curve defined by this term is not affected by water temperature change. This is because energy as such is not affected by temperature change. Likewise, water density has no effect on the pump curve- though density does affect pump power requirements" B&G Engineering Design Manual.

bob_25

Density

Hi Jerry, "Since foot head is a simple energy statement, a pump curve defined by this term is not affected by water temperature change. This is because energy, as such, is not affected by temperature change. Likewise, water density has no effect on the pump curve-though density does affect pump power requirements". B&G Engineering Design Manual. bob