Pumps, flow and restrictions.....

[AKKAMAAN]

Egon, NPSH is very important when pumping water at 7000 GPM!!!!! Them pumps scare the **** out of you when that is lacking!!!!!:laughing::laughing:

Thanks mmurphy....you said it better then I ever could have....negative centrifugal pumps that can not "suck" at start up.....need priming....
Fire fighters knows a lot about this.....

 

[AKKAMAAN]

What head pressure?

See Wikipedia for NPSH, head pressure

There's a plethora of things I know a very little about, by Gar!

Great quote....Applies to me too, but I do not want to talk about those things.....

 

[mmurphy]

By the way AKKAMAAN, this thread really got alot of us thinking by all the posts and head scratching going on. (My bald head is getting raw!) I think that is what you were really intending on. Or am I still "Fishing"?:laughing:

 

[AKKAMAAN]

By the way AKKAMAAN, this thread really got alot of us thinking by all the posts and head scratching going on. (My bald head is getting raw!) I think that is what you were really intending on. Or am I still "Fishing"?:laughing:

Love you mmurphy....you have the right attitude to my posts....yes, I try to scramble the wiring in your heads a little......and then I'll try rewire the "right way".....:laughing:

pushing oil (pump flow), is nothing complicated....just plain mechanics....just liquids instead of solids....add up ten cars on the street and push them from behind....1 car per second through the intersection (flow rate)....you can use the same force (pressure) as long as resistance is the same....if some one applies the brakes in the front car, you need to increase force to make 1 car per second through the intersection.....if you (prime mover or engine) "bog down"....less cars per second (decreased flow), but if you push harder, add another "horse" aka throttle the engine (increased pressure), car per second (flow) will stay the same.

More confused now??

 

[Egon]

just liquids

Tried to pump some ice once!

 

[AKKAMAAN]

Tried to pump some ice once!

If you failed you definitely did not have enough "head"....:laughing: LOL

 

[Egon]

did not have enough "head"....:laughing:

Not only that the Beer was froze too!

 

[AKKAMAAN]

Not only that the Beer was froze too!

Found this at DynaFlow website

" A Gear Pump is a "positive displacement" pump, unlike a centrifugal pump which is a "velocity" type pump. As the term suggests, a "velocity" type pump generates pressure and flow from the tangential and angular velocities(kinetic energy) (my comment: Negative pump) imparted to the liquid by the speed and shape of the impeller. In a "velocity" type pump, pressure and flow can be modulated by throttling a discharge valve."

Which means that is NOT the case (throttling flow with orifice) with a positive fixed gear pump flow.....

Link to DynaFlow Gear pump page....good reading thx Egon!!

 

[wdchyd]

I can see many posts where arguments about using larger fittings, hoses etc will increase flow....in a constant flow system, it can only happen by diversion of flow.....
However, larger fittings will reduce pressure, increase efficiency and save energy.

Totally, Totally Agree!!!!

Most people adding or designing hyd sys's think too much about $ when buying fittings, hoses and components but don't consider pressures,efficiency and heat issues.....(until problems come up).....

battling one now in my new Kubota B2320 w/BH.....New, dealer installed, all factory hoses and fittings......Darn thing heats up way too much after 1-2 hrs of digging ...I know it's wrong, Dealer tells me word from Kubota is 150 to 170 degrees is normal......

What's wrong with it is all the hoses are plumbed with 1/4 ID hyd hoses...(in & out & work ports).....You can hear them hissing from the pressure drop and WPR's prematurely kicking off...

This weekend I brought home a Flow Meter, QC's,& hoses to do some troubleshooting on my own......

My suspicion is the hoses are too small or crimped too tight.....Took a new Gates 1/4" ID hose end out of stock and measured the hole ID at .152.....this is before crimping!!!.....ARGGGG......(have not removed OEM hose yet)

Maybe you guys can help and do the math for me to see what the FPS velocity is going though these hose ends after flow readings are taken......the adapters look OK cuz the orifices are larger than .250"......

Sorry to ramble but this goes along with what AKKAMAN's been saying about slowing thing's down with restrictors.....I don't like them and don't install them....(accidentally or intentionally):2cents:

 

[AKKAMAAN]

Totally, Totally Agree!!!!

Most people adding or designing hyd sys's think too much about $ when buying fittings, hoses and components but don't consider pressures,efficiency and heat issues.....(until problems come up).....

battling one now in my new Kubota B2320 w/BH.....New, dealer installed, all factory hoses and fittings......Darn thing heats up way too much after 1-2 hrs of digging ...I know it's wrong, Dealer tells me word from Kubota is 150 to 170 degrees is normal......

What's wrong with it is all the hoses are plumbed with 1/4 ID hyd hoses...(in & out & work ports).....You can hear them hissing from the pressure drop and WPR's prematurely kicking off...

This weekend I brought home a Flow Meter, QC's,& hoses to do some troubleshooting on my own......

My suspicion is the hoses are too small or crimped too tight.....Took a new Gates 1/4" ID hose end out of stock and measured the hole ID at .152.....this is before crimping!!!.....ARGGGG......(have not removed OEM hose yet)

Maybe you guys can help and do the math for me to see what the FPS velocity is going though these hose ends after flow readings are taken......the adapters look OK cuz the orifices are larger than .250"......

Sorry to ramble but this goes along with what AKKAMAN's been saying about slowing thing's down with restrictors.....I don't like them and don't install them....(accidentally or intentionally):2cents:

If your Kubota have a constant pressure system, restrictors wont be that "bad"...constant pressure systems with variable pump, do not divert flow...

I general I agree that manufacturers never over size any lines...always at low end of sizes...

Calculate pressure drop in hoses and fittings


or use two identical gauges...one in the beginning of the line and one at the end of the line.....problem though is to be sure they are calibrated the same....there are also special pressure drop gauges