Pump oil-water separator diameter difference?

[MrSam]

I'm wondering if the inside diameter of an oil-water separator/filter makes a difference in terms of pumping speed and how much air gets into the gun per stroke? I have two identical 3-stage hand pumps, one with a smaller ID filter, and one with a larger ID filter. Both use a cheap cotton filter. It feels like the one with the larger diameter filter is easier/faster to pump, but I cant see why that would be the case. Both pumps were acquired around the same time, and have around the same amount of wear, so I don't think that's a factor. I've also changed the filter on both pumps, just last night, and made sure they were clean. Neither pump is leaking, nor pumping an unusual amount of oil.

[Fate]

The time difference you note is likely due to the larger internal volume of one filter compared to the other... because the pump must pressurize the filter ahead of the gun's valve.

I have a Yong Heng compressor, and when using a larger more complex output filter (as compared to the small single-element OEM filter) the pump takes significantly longer to begin pressurizing the gun.

[Back_Roads]

 Have you used them up to full pressure, and counted the strokes to reach it? If it still feels easier when reaching full pressure, it may be air acts something like water, there was a trick for increasing waterflow for pond waterfall pumps, using larger diameter hose off a smaller pump exit hole, but it does take longer for water to start flowing over the falls.

[kbstingwing]

it's probably not the filters causing the issue but Microbore hose inside diameter, one pumps hose might have a larger inside diameter than the other, or there could be a restriction in the line of other pump causing it to be harder to pump, that would be my guess.