Water requirements

[mae1133]

We have two pieces of equipment that requires process water in a new building. One requires 60 gpm @ 70 psi and the other requires 50 gpm @ 65 psi and will operate concurrently. We want to advise the owner of the total flow/pressure required coming into the building. Is this simply the combined flow at the higher pressure? So 110 gpm @ 70 psi? This is just a proposal stage, so just trying to advise the client on what they will need to supply for water. Don't require a bunch of analysis at this point. Thanks

 

[LittleInch]

It's close enough.

Difficult to believe that the lower rated piece of equipment is pressure sensitive so if it gets water at 70psi instead of 65 it might consume a little more, but won't break it.

But 70 + 50 is 120, not 110.....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

If you don't want to do an exact analysis now, and 5 psi is not much of a difference to worry about as pressures go, it could be reasonable to give them the total flow at the highest pressure of 120 gpm at 70 psig (gage pressure), however you will probably need to give them a slightly higher pressure at the supply connection point, to account for pipe and valve pressure losses from there to the machines themselves. That will depend on pipe diameter and the distance between supply point and each machine's location. You should be able to account for that with something like another 10 to 25% of pressure, so I would up that supply point pressure to 100 psig, noting that 100 psig is a nice and easy round number to remember.
(Thanks LittleInch, I believed the 110 gpm number.)
“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[mae1133]

Thanks LittleInch, but I think you're mixing my flow and pressure numbers. The flow is 60 gpm and 50 gpm, so 110 gpm was what I was suggesting as a flow requirement but I would suggest a bit more as a safety factor. Likewise for the pressure, I would tell them a bit higher as an allowance for losses to the equipment. I just wanted to make sure I was providing a proper estimate.

 

[1503-44]

He's right. This time I added them myself.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"

 

[LittleInch]

Apologies. I must have gone number blind!

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[fel3]

LittleInch...

Happens to all of us. Back in 1978, my very excellent DiffEq professor joked one day--after making a big blunder on the chalkboard--that his BS was in electrical engineering, but he switched from engineering to mathematics (MS, PhD) because "I couldn't keep the numbers straight."

Fred

============
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[1503-44]

After writing equations for 3 days, my red & white striped searsucker suit, grizzly bearded, exploration physics, crazy mad professor would always find a mistake in a wave reflection equation he wrote on the first day and then spend the next week sleeping overnight in his office and revising all equations since in the next 3 weekly classes. Absolute nutter.

“What I told you was true ... from a certain point of view.” - Obi-Wan Kenobi, "Return of the Jedi"