# Thread: Calculating GPM

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## Calculating GPM

Hello all. New to the site, been in the trade about 15 years. Got a new employer, and we do work on chillers ( air cooled screw, scroll, and recip). How do you know you have proper water flow (gpms) through a chiller?How do you know what it's supposed to be? I appreciate feed back. I tried to do a search on here, but came up empty.

2. The iom manuals of the machine will tell you the design gpm, minimum and maximum for that particular machine. At the machine using the same gauge to measure supply and return pressure with the chiller at full load, you apply this formula:

Gpm across barrel
Gpm (actual)=design gpmx(square root of actual divided by design)
A=234 x sq rt of 4/6

3. 2.5 gpm per ton for chilled water

look at your pumps and read gpm and head

if pump is correct and gpm is correct

find out what the pressure drop through the chiller is supposed to be
if it is correct

then

use

gpm x 500 x delta t

this should get you close

then you will have to learn approach.

frank

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A lot of Ioms will have a graph to assist you in calculating GPM.

Design can vary per application .

There are rules of thumb.

There are math calculations to perform .

I'll look around and see if I can come up with something for you....

5. Originally Posted by supertek65
2.5 gpm per ton for chilled water

look at your pumps and read gpm and head

if pump is correct and gpm is correct

find out what the pressure drop through the chiller is supposed to be
if it is correct

then

use

gpm x 500 x delta t

this should get you close

then you will have to learn approach.

frank
Ya I forgot the part about the pump. Oops!

Thought I was gonna get an atta boy from ya....ya not!

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Here it is.

7. New Guest
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You guys are awesome. Thanks for the replies.

8. Professional Member
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Take a look at this.

9. when you can snatch the pebble from my hand!
it will be time for you to leave grasshopper!

http://www.youtube.com/watch?v=gASY7Lj5GPQ

Originally Posted by ryan1088
Ya I forgot the part about the pump. Oops!

Thought I was gonna get an atta boy from ya....ya not!

10. Originally Posted by supertek65
when you can snatch the pebble from my hand!
it will be time for you to leave grasshopper!

http://www.youtube.com/watch?v=gASY7Lj5GPQ
Bruce lee got the shaft on that one!

11. i think you are correct!

of course they are both dead now!

i looooove bruce lee!

have you ever seen him play ping pong with wooden matches???????? FREAK!!!!!!!!

Originally Posted by Joehvac25
Bruce lee got the shaft on that one!

12. Originally Posted by supertek65
i think you are correct!

of course they are both dead now!

i looooove bruce lee!

have you ever seen him play ping pong with wooden matches???????? FREAK!!!!!!!!
I have seen the old ping pong videos, he's the ****. If you want your bubble burst read the book "bruce lee unsettled matters".

They found David in a bad spot lol.

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