Calculating flow

9mmCensor · 01-26-2005, 12:39 PM

Flow is something that is measured, not calculated right?
Question from An OCF thread

nexxo · 01-26-2005, 02:09 PM

It is both. Sometimes you have to convert the measurement values, and that means calculation (e.g. my flow sensor puts out 9000 rpm-ish, and I have to divide that by 6000 to get litres/minute).

Also (if you're a real cooling ubergeek, like, say, Bill A.) you can calculate expected flow from variables such as pump capacity/head, flow resistance etc.

BillA · 01-26-2005, 02:11 PM

by us, yes
other than some component velocities, system flow can be estimated with the astd P-Q curves
-> I have NOT seen any good correlations, though that may be because I have not looked

note that 'hand calcs' of this sort are ±10%, or more
I never bother, just test

Jimbo Mahoney · 01-26-2005, 02:32 PM

What flow sensor do you use nexxo?

Risky · 01-27-2005, 02:37 AM

Quote:

Originally Posted by Jimbo Mahoney

What flow sensor do you use nexxo?

He uses a SF800

Jimbo Mahoney · 01-27-2005, 07:40 AM

Quote:

Originally Posted by Risky

He uses a SF800

They look expensive...

bigben2k · 01-27-2005, 01:29 PM

They run about $80 USD, and you need a frequency meter to go with it.

Otherwise, the accuracy is ~+/- 1% (plus the error of the frequency measure). Cheapest deal I've seen yet.

Blackeagle · 01-30-2005, 06:52 PM

Quote:

Originally Posted by bigben2k

Cheapest deal I've seen yet.

While not cheap, a GOOD PSI gauge (.1PSI readings) located between the pumps outlet & the first point of the loops restriction would be less expensive that that. Not as accurate, but still more than good enough for those who just want to know what the flow rate of their loop is.

Just convert the PSI reading to feet of water and then refer to your pumps curve.

bigben2k · 01-31-2005, 11:50 AM

True, but you still don't know the flow rate.

I gotta check out this OC thread...

01-26-2005, 12:39 PM	#1
9mmCensor Cooling Savant Join Date: Apr 2004 Location: Canada Posts: 219	Calculating flow Flow is something that is measured, not calculated right? Question from An OCF thread

01-26-2005, 02:09 PM	#2
nexxo Cooling Savant Join Date: Jul 2002 Location: Brimingham, UK Posts: 385	It is both. Sometimes you have to convert the measurement values, and that means calculation (e.g. my flow sensor puts out 9000 rpm-ish, and I have to divide that by 6000 to get litres/minute). Also (if you're a real cooling ubergeek, like, say, Bill A.) you can calculate expected flow from variables such as pump capacity/head, flow resistance etc. __________________ "There is a thin line between magic and madness"

01-27-2005, 01:29 PM	#7
bigben2k Responsible for 2% of all the posts here. Join Date: May 2002 Location: Texas, U.S.A. Posts: 8,302	They run about $80 USD, and you need a frequency meter to go with it. Otherwise, the accuracy is ~+/- 1% (plus the error of the frequency measure). Cheapest deal I've seen yet. __________________ WBTA (Water Block Testing Alliance) Nordic Hardware WC 101

01-31-2005, 11:50 AM	#9
bigben2k Responsible for 2% of all the posts here. Join Date: May 2002 Location: Texas, U.S.A. Posts: 8,302	True, but you still don't know the flow rate. I gotta check out this OC thread... __________________ WBTA (Water Block Testing Alliance) Nordic Hardware WC 101

01-26-2005, 02:11 PM	#3
BillA CoolingWorks Tech Guy Formerly "Unregistered" Join Date: Dec 2000 Location: Posts: 2,371.493,106 Posts: 4,440	by us, yes other than some component velocities, system flow can be estimated with the astd P-Q curves -> I have NOT seen any good correlations, though that may be because I have not looked note that 'hand calcs' of this sort are ±10%, or more I never bother, just test

01-26-2005, 02:32 PM	#4
Jimbo Mahoney Cooling Neophyte Join Date: Jan 2005 Location: UK Posts: 96	What flow sensor do you use nexxo?

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