Bernoulli equation in a closed loop system

[icham]

Homework Statement

Bernoulli equation in closed loop system

Relevant Equations

H=p/ρg+V2/2g+z2-p/ρg+V2/2g+z1=hs-hf

P1 = 5psi P2= 15psi , Z2-Z1 = 0, i assume V2 =V1 because velocity of water is the same everywhere in a pipe of constant diameter
is H friction = H pump = 10psi ?
Please help

 

[Chestermiller]

Correct. Is that really your question?

 

[icham]

how come?
(p2- p1) +H friction = Hp
(15psi-5psi) +10psi = 10psi ?

 

[Chestermiller]

how come?
(p2- p1) +H friction = Hp
(15psi-5psi) +10psi = 10psi ?

The thing is in a loop, so if points 1 and 2 are right next to one another, say in the inlet pipe to the pump, P1 = P2

 

[icham]

The thing is in a loop, so if points 1 and 2 are right next to one another, say in the inlet pipe to the pump, P1 = P2

but gauges show 15psi and 5psi and it should be a differential pressure for pump to work

 

[Chestermiller]

but gauges show 15psi and 5psi and it should be a differential pressure for pump to work

Please specify where you are placing points 1 and 2.

 

[icham]

Please specify where you are placing points 1 and 2.

as showns on the circuit, P1 is just after the expansion tank and P2 is after pump let say 10 feet or like half way between pump and the resistance

 

[Chestermiller]

as showns on the circuit, P1 is just after the expansion tank and P2 is after pump let say 10 feet or like half way between pump and the resistance

OK. Then there are two Bernoulli equations that you can write: $$\frac{P_2-P_1}{\rho g}=\Delta H_{pump}$$That applies across the top; and $$\frac{P_2-P_1}{\rho g}=\Delta H_{friction}$$That applies across the bottom.

 

[icham]

OK. Then there are two Bernoulli equations that you can write: $$\frac{P_2-P_1}{\rho g}=\Delta H_{pump}$$That applies across the top; and $$\frac{P_2-P_1}{\rho g}=\Delta H_{friction}$$That applies across the bottom.

Thank you very much ! you've made my day