Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Flowmeters and Turndown Ratio - Rangeability

Turndown ratio for flow measurement devices like orifices, venturi meters etc.

Sponsored Links

Turndown ratio - rangeability - is often used to compare the span - the range - of flow measurement devices.

Turndown Ratio - Rangeability

Turndown ratio can be expressed as:

TR = qmax / qmin                                  (1)

where

TR = Turndown Ratio

qmax = maximum flow

qmin = minimum flow

Maximum and minimum flow is stated within a specified accuracy and repeatability for the device.

Example - Turndown Ratio for an Orifice Meter

The turndown ratio - TR - for an orifice meter with maximum flow of 12 kg/s and a minimum flow of 3 kg/s can be calculated as:

TR = (12 kg/s) / (3 kg/s)

    = 4

    - normally expressed as turndown ratio of 4:1

This is a typical turndown ratio for a orifice plate. In general a orifice plates has turndown ratio between 3:1 and 5:1.

Turndown Ratio and Measured Signal

Flowmeter - turn down ratio and measured signal span

In a flow meter based on the orifice or venturi principle the differential pressure upstream and downstream of an obstruction in the flow is used to indicate the flow. According the Bernoulli Equation the differential pressure increases with the square of flow velocity. A large turndown ratio will cramp the measurement signal at low flow rate.

Sponsored Links

Related Topics

Related Documents

Tag Search

  • en: turndown turn down flow ratio measurement device
Sponsored Links

Search the Engineering ToolBox

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the SketchUp Pro Sketchup Extension Warehouse!

Translate this page to
About the Engineering ToolBox!

Privacy

We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.

Citation

This page can be cited as

  • Engineering ToolBox, (2003). Flowmeters and Turndown Ratio - Rangeability. [online] Available at: https://www.engineeringtoolbox.com/flow-meters-turndown-ratio-d_494.html [Accessed Day Mo. Year].

Modify access date.

. .

close

3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Scientific Online Calculator

Scientific Calculator

12 7

Sponsored Links
.