single 2"suction line presure limits

[Neto]

so i have a 10k gallon pool that has an attached elevated spa. It has 3 main drains (2" individual pipes) and one skimmer line (2") for suction and three 2" pipes that feed 5 returns and 6 spa jets... Since i have the intelliflo vsf, i am not sure how much gpm can the system take when i am in spa mode, that will convert the system into one 2" main drain and one 2" return pipe that supplies 6 jets. I am setting it up for 70 gpm but i am getting a warning on maximum pressure limit reached (30psi) and that lowers the flow to 65gpm. My filter gauge says 17 psi, this is the pentair cartridge 520sqft filter.

So my question is, what is the maximum safe levels a single pipe can handle? I would like to assign a number on the pump so i can use and maintain safe levels on the pipes when im using the spa only.

 

[HermanTX]

From what I have read in other posts for 2" PVC - is 63gpm which maintains flow under the velocity of 6ft/sec guideline (for suction) and use 84gpm on pressure side to keep under velocity of 8 ft/sec
I am asking @ajw22 to provide his thoughts as he has a lot of knowledge on pipe velocities and flow dynamics.

 

[ajw22]

So my question is, what is the maximum safe levels a single pipe can handle? I would like to assign a number on the pump so i can use and maintain safe levels on the pipes when im using the spa only.

2" Schedule 40 PVC pipes are rated at 280 PSI@73F or 61 PSI@140F. You do have all schedule 40 PVC pipes and fittings?

http://www.nationalpipe.com/document_files/1383847944_Plumbrite.pdf#:~:text=having%20met%20Standards%2014%20and%2061%20requirements.%20PVC,140%C2%BA%20F%20(PSI)%20Minimum%20Socket%20Feet%20Per%20Pallet

You are not going to over pressurize your pipes with your Intelliflo pump. Up the PSI limit on the pump to 50.

The weak link in your system is probably the filter. I would not let the filter PSI get above 25-30 PSI.

If you run your Intelliflo pump in RPM rather then GPM the PSI limits will not be applied.

 

[Neto]

2" Schedule 40 PVC pipes are rated at 280 PSI@73F or 61 PSI@140F. You do have all schedule 40 PVC pipes and fittings?

http://www.nationalpipe.com/document_files/1383847944_Plumbrite.pdf#:~:text=having%20met%20Standards%2014%20and%2061%20requirements.%20PVC,140%C2%BA%20F%20(PSI)%20Minimum%20Socket%20Feet%20Per%20Pallet

You are not going to over pressurize your pipes with your Intelliflo pump. Up the PSI limit on the pump to 50.

The weak link in your system is probably the filter. I would not let the filter PSI get above 25-30 PSI.

If you run your Intelliflo pump in RPM rather then GPM the PSI limits will not be applied.

Thanks for the suggestions, do you mind explaining why the weak link is the filter? I thought I bought the top of the line cartridge filter from pentair (Clean & Clear Plus Cartridge Filter 520 sqft. - 160332). The flow rating on it is up to 150GPM.. Maybe I should have bought a DE filter?

 

[ajw22]

Type of filter does not matter much. It is the construction of a consumer filter pressure vessel. They are not designed for high pressure and will lead to cracks.

 

[HermanTX]

do you mind explaining why the weak link is the filter

My DE filter has a maximum working pressure of 50psi. Most filters are a large dome (lots of square inches of area) and secured with a wrap around clamp so just a little pressure multiples into a lot of force (lbs.) thus the relatively low working pressure. I never let mine go above 30psi (single speed pump) and from what I read on the forum, many that have VSP's have pressure in 10-20psi range when run at moderate RPMs.