Blueline Pump

[Sherri]

Anybody know if it would be okay to adapt the feed to the pump up from 3/4 inch to 1 inch? I know with some pumps it is a big no-no -- but I don't know about the blueline. I am wanting to switch out pumps but the plumbing is all 3/4 inch. I can sort out the output okay just don't know if I can adapt from the 3/4 inch plumbing to the 1 inch without killing the pump.

 

[cujo6984]

you will probably get cavitation i wouldn't do it

 

[Sherri]

What if I had a T with 1 1 inch by 2 x 3/4 inch, had one feed loop over the top of the tank to feed the pump with the 3/4 inch plumbing in place?

 

[Miller]

I wouldn't see any problem upsizing the plumbing, you get in trouble when you down size the plumbing where the pump pulls watere in.

 

[Sherri]

Yea -- I figured it is a problem -- but actually if we have a T with one 3/4 inch end to fit into the existing plumbing, 1 1 inch to go on the inlet to the pump, and 1 1 inch that is plumbed over the top of the tank, then we will definitely get enough water volume and the pump will be primed. Still trying to figure out how to add a tank into the system!

 

[rjdudek]

I have had a Blueline running on a 1.5" line for 5 years. You should have no problem. As long as the piping all the way back to the source is either 1" or greater there is no chance of cavitation as long as the pipe is either all sloped to the pump or under the level of the feed water. The trouble occurs when you go from small to large then back to small sized pipe or fittings. For example if you had a 3/4 bulkhead feeding a 1" pipe then a 3/4 pump inlet the lower velocity in the 1" pipe may cause air entrapment leading to non-inertial cavitation. A second factor in the small/large/small pipe set up is the large pipe will see a much reduced flow velocity and be more prone to bio build up on the pipe wall.

The Blueline effectively has no pump suction; drawing over the sidewall will lead to problems when the vacuum breaks. I have seen people do it but it is engineering a failure point into a system that generally does not need to be there.

If your bulkhead is 1” run 1” pipe to the pump stepdown fitting and there should be no problem if it is all below sump water level.

 

[67belvedere]

it is ok to up on the pipe diameter its when you go smaller that you get cavitation from trying to get to much water through to small of a hole

 

[Sokretys]

Interesting. Never heard of cavitation till now. Sorry to steal your thread Sherri, but could a 1" union on the output of a mag 7. would that cause air bubbles? i either have a cavitation issue of some king or there is a venturi in the plumbing...

 

[rjdudek]

I don't believe there is any way for the outlet to be the cause of a cavitation on the pump, that is the "pressurized" end of the pump. I would check for an air leak into the pump feed, volute housing or the outlet pipe close to the pump.

 

[Sherri]

Mr. Dudek -- long time no see -- how are you?

Anyway, we finally figured it out. The bulkhead is 1 inch (which we finally looked at!) and was adapted down to 3/4 inches to feed into the genx 40. So we are going to get all of the plumbing glued up and let it sit while, and then drain the tank, remove the bulkhead, put in a new 1 inch bulkhead and then ... the whole thing is done the right way. Always takes a bit of time to figure these things out! Duh.

Then the big challenge will be balancing the flow between the two tanks.

 

[rjdudek]

Been well, rebuilding tanks after the winter of destruction.

 

[Sherri]

It was a brutal winter. Nice to "see" you again.