DI water Flow


Thread Starter


Hi All:

Can anyone tell me what are the best flow meter to use to measure DI water ? I need the accuracy to be +-0.25% or worst case 0.5%. Thanks.
<< Can anyone tell me what are the best flow meter to use to measure DI water ? I need the accuracy to be +-0.25% or worst case 0.5%. >>

Dear Colleagues,

The above statement does not include the following essential information:

1) Are the percentages in % 5 of ACTUAL or in % of FULL (maximum) flow.
2) Down to what minimum flow would you like to have that inaccuracy (error limit), in other words, what is the desired rangeability of the installation?

Best regards, Bela Liptak
The best way to measure DI water with this accuracy (+/- 0.25% to +/- 0.5% of indicated rate) is with a transit time ultrasonic flow meter. Several manufacturers make designs specifically for ultrapure piping and DI water, especially for the semiconductor industry. Panametrics, Controlotron, Fuji, Aaliant, and Nano-Master provide designs specifically for the ultrapure water industry. These tend to be a bit pricey.

Next best, with reduced accuracy (roughly 1% Full Scale), is with vortex-shedding designs. Asahi-America and Nano-Master provide designs
specifically for ultrapure water. Less pricey, but still costly.

Last but most inexpensive, single jet enclosed turbine flow meters and paddlewheels can be used for these applications with accuracies of 1-3% of
span. McMillan, Malema, SeaMetrics and others make these meters. Pretty inexpensive.

Your choice.

Walt Boyes

Contributing Editor, Flow Control Magazine

Walt Boyes--MarketingPractice Consultants
21118 SE 278th Place - Maple Valley, WA 98038
425-432-8262 home office - 253-709-5046 cellphone
eFax: 801-749-7142 - email: [email protected]
Water flow measurement:
You simply missed the most critical spec in your request. The flow RANGEABILITY. Any way.
I have been an adept of the orifice plate.
The differential pressure is in direct response of fluid dynamic. The orifice plate is a mass flow meter in its basic physic.
The ISO standard has a unique formula.
An ordinary industrial installation is ±.6%.
A calibrated installation is within your tolerance
The only problem is the rangeability. Generaly considered 1/3. Modern XTR's allow 1/5.
At low flow (low DP), XTR is not faithfull; because the square root extraction the relative error may become greater than the measurement.
This is why some installations have several XTR.
The three major names
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