-
Member Post posted an update
What are some methods of estimating GPM flow on small 10-20 ton process chillers with no water pressure ports.
All i have is a tank temp sensor and a leaving water temp sensor the pump is constant speed . Can i estimate gpm by using delta T?
Member Post, Member Post and 2 others7 Comments-
@AGON17 you can calculate the GPM, but you will need to know the tonnage you are pulling from the water it needs to be accurate if you want an accurate result.
12,000 BTU’s = 1 ton
The ANSI standard is 2.4 GPM/ton and 10 degree delta T with 44°F leaving water and 54°F entering water on the evap.1. Using tons: GPM = (24 × Tons) / ΔT
Example: (24×100 Tons) / 10°F = 240 GPM2. Using Press drop across evap: GPM₂ = GPM₁ × √(ΔP₂/ΔP₁)
For future use if you need it: GPM1 and Delta p1 are oem design, 2 is measured.3. You can also check pressure drop across pump, and use the pumps flow curve in the pump manual to calculate GPM.
All of this will not be as accurate as taking a pressure reading, and comparing it to design.
I’m sure some other guys will chime in as well. let us know
-
@the-chiller-guys that all sounds good on paper. Without knowing the pressure drop, anything is just a guess.
Guy needs to buy a gauge. It’s not going to break the bank!!!1-
@craig-moodie agreed, but he mentioned there is no pressure ports, i think he just wants a ballpark for an idea of where his problem is. If its 2 am, im going to calculate it, and go back and install pressure taps at a shutdown.
I agree though, pressure taps should be welded on if they aren’t there. @AGON17 A good follow up should include a tap on supply and return with valves going to a common gauge.
1 -
@craig-moodie yeah unfortunately not pressure taps so an estimate is as good as I’m gonna get. They are small 20 ton scroll 410a process chillers with constant volume pumps
1
-
-
@the-chiller-guys Thanks for the detailed update!
1-
@AGON17 for sure, Craig is correct though, this is a ballpark to get you info, but a gauge and taps should be added.
If its impossible to be shut down, you can add hot taps, FYI
1 -
@AGON17 i did make this FREE AI tool to help guys with some of the calculations, and checking flow, you can pin it to your feed on Chat GPT. I cant remember if you need a paid subscription or Not with chat gpt, but check it out and let me know.
https://chatgpt.com/g/g-6890b74cb640819197690dd4a6de47b4-chiller-guys-ai-troubleshooter
As always, its best to double check with us, or someone at your shop before going off of the info, but I am hoping it will get guys pointed in the right direction with flow, and other things.
1
-
-
-
