A pipe is not a "restrictionless device", there is a very real restriction to flow through a pipe, so the question needs a bit of help. Are you looking to find out how to determine pressure drop (ie: restriction to flow) through a pipe? Or are you asking about something else?DHJenkins said:Is it possible to calculate the flow rate of water through a restrictionless device (a tank, for example) if you know the inlet & outlet diameters and pressures?
I've been looking all over, but all I can seem to find is formulas for pressure drop in a length of pipe...
Thanks!
You missed my point. My point was that if the device has no effect on the flow rate, then the flow rate is determined entirely by what is going on with the input and ouput piping: and you provided no information about them besides their size.DHJenkins said:Russ - I'm not looking for the effect on flow rate, I'm looking the actual flow rate - a number, specifically in GPM and preferably within 5% +/-
If there is a pressure drop, then that means there is a restriction. The restriction causes the pressure drop. Unfortunately, you need to know the flow coefficient (Cv) to find the flow at a given pressure drop. That's based on this formula (in step 3): http://www.cheresources.com/valvezz.shtmlThis small loop is tapped off of a larger supply/return loop. There are 2 valves - an inlet & and outlet. The inlet remains wide open so as to not starve the coils for water, and flow rate is adjusted by opening/closing the outlet valve. The inlet pressure is 45psi, and the outlet pressure is 35 psi...
If it is a closed system, the height doesn't matter. Do you have pressure gages anywhere else? At the pumps? At the mains before the valves? It sounds like the pressure gages you are referring to are on either side of your heat exchanger, between the valves. Is that correct?...what is the flow rate of water through this machine? Also, maximum pressure drop (with both handles wide open) is 20 psi.
- I imagine this has to do with the height; the machine is located approximately 50' below the pumps.
To calculate the flow rate, you can use the Bernoulli's equation which states that the total energy of a fluid remains constant. This equation can be written as Q = A1V1 = A2V2, where Q is the flow rate, A is the cross-sectional area and V is the velocity. By rearranging the equation, you can plug in the given inlet and outlet diameters and pressures to calculate the flow rate.
The Bernoulli's equation can be used for incompressible fluids, which means that the density of the fluid remains constant. This includes liquids like water and oils. However, for compressible fluids like gases, a modified version of the equation is used which takes into account the change in density with pressure.
The inlet and outlet diameters have a direct impact on the flow rate. A larger diameter means a larger cross-sectional area, allowing more fluid to pass through in a given time. This results in a higher flow rate. On the other hand, a smaller diameter would restrict the flow and result in a lower flow rate.
The relationship between pressure and flow rate can be described using the Bernoulli's equation. As the pressure increases, the velocity of the fluid decreases and vice versa. This means that a higher pressure would result in a lower flow rate and a lower pressure would result in a higher flow rate, assuming all other factors remain constant.
Yes, the flow rate can be increased by adjusting the inlet and outlet pressures. By increasing the pressure difference between the inlet and outlet, the velocity of the fluid would increase, resulting in a higher flow rate. However, this also depends on other factors such as the viscosity of the fluid and the size of the pipe.