Okay - pressure requirement for depth only is very close to 5cfm + 3.5 for 500ft of 0.75"ID tubing, + maybe 0.5 to 1psi for fittings, manifold, connectors, diffuser requirement = 9.0-9.5psi which is very close to the maximum operating pressure of 10psi suggested by manufacturer for a rotary vane. If possible, take Esshup's advice and use the 1" tubing for underground airline. When at the pond's edge reduce the 1"ID to the 5/8"ID airline; estimated final psi: 5psi (depth),+0.5psi (500' 1"tubing), + 1 psi (misc) = total 6-7psi. This 6-7psi will be easy 'work' for the compressor and should extend the life span of the vanes & motor bearings. Report back your final psi when you get the system running.
For our information whichever diameter tubing that you use, when you have the airline installed, please measure the air pressure of the system open flow with no diffuser attached at the end of the airline. It is best if you use a low pressure air gauge (often 30psi gauge). This will be the base psi needed to push air through the pump, manifold, connectors & 500' of tubing. Then when you add the diffuser, any extra pressure will be from pushing air through the diffuser and water depth. From these psi results we can learn if our calculations were correct.
Last edited by Bill Cody; 09/03/13 10:26 AM.
