I'm looking at doing some IP X5 rated water tests. And was just curious how my hose equipment got its numbers.
The internal diameter of the hose is 6.3mm, and according to the pressure gauge I have attached to it, having a 6.3mm diameter nozzle at 2.9psi would get me a flow rate of about 12.5 L/min.
However, isn't this too little information to get flow rate? I understand that in bernoulli's equation:
$$P_1 + \frac{\rho}{2}\cdot V_1^2 + \rho\cdot g\cdot h_1 = P_2 + \frac{\rho}{2}\cdot V_2^2 + \rho\cdot g\cdot h_2$$
Assuming horizontal hose, I get the equation:
$$P_1 + \frac{\rho}{2}\cdot V_1^2 = P_2 + \frac{\rho}{2}\cdot V_2^2$$
I'm stumped here. How do I get $P_1$ and $V_1$? $\rho$ is the density of water, 1000kg/m3, $P_2$ is the pressure of the hose at the gauge, so 3psi, and I am looking for $V_2$.
If I assume that the water reservoir is "infinite" and open to the air, perhaps I can say that $P_1$ = 0psi, and $V_1$ ~= 0. So I get:
$$0 = P_2 + \frac{\rho}{2}\cdot V_2^2$$
But, then here we get, if we isolate for $V_2$:
$$-P_2 = \frac{\rho}{2}\cdot V_2^2$$
Eventually, we'll get $V_2$ is the sqrt of a negative number, which seems wrong.
