👉 " Three Times Better (Engineer) "

The 3 Things You will learn are as follows.

• My Flowmeter selection Algorithm.

• How to Calculate Orifice Straight Length.

• How to handle things (You have not done before)

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#1 -Engineering Question

Hello Anti-Copy Paste Engineer,

In my career,

I have been part of 10,000+ Flowmeters Selection process

and today's article is a summary of my entire experience.

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Below is a bullet point summary, but if you need a detailed PDF summary of Flowmeter Selection (With Practical Examples).

Then Reply to this email with "Flowmeter Selection PDF" And I will send it to you for your future reference.

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Let the Fun Begin......

How Professional Engineers Select a Flowmeter

Flowmeter selection is not a meeting

Where you sit with 20 different flowmeter technologies and ask:

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Professional engineers do almost the Opposite

They begin with all available options.

Then they systematically "Delete"

The technologies that cannot handle the application.

By the end,

Only two or three realistic choices remain.

That is when the actual selection begins.

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Five-step elimination process

Here is the five-step elimination process:

• Fluid Type
• Measurable Range
• Relative FM Accuracy
• Physical Plant Limitations
• Cost Optimization (This comes LAST)

Let us apply each filter.

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Filter 1: Physics (What Is Flowing?)

Start with the fluid.

Yes, Before even discussing

• Accuracy,
• Price or Vendors
• Or the famous Straight Length Requirement

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Is it liquid, gas or steam?

This first question immediately removes some options.

→ If it is steam:

Delete the following

• Electromagnetic Flowmeters
• Positive-displacement Meters
• Coriolis Mass Flowmeters

These are not designed for steam

The most common survivors are:

• Vortex
• Orifice (Or another DP element)

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→ If it is Gas:

Delete the following Flowmeter:

• Electromagnetic Flowmeters
• Liquid-only ultrasonic Flowmeters
• Positive-displacement Flowmeters

The remaining popular options may include:

• Coriolis FM
• Vortex FM
• Ultrasonic FM
• Thermal mass FM
• Differential Pressure FM

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→ If it is Liquid:

Most technologies (more or less) remain initially.

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Now we need more questions about the Liquid.

Is the liquid electrically conductive?

A practical first screening rule is:

• Above 20 µS/cm: keep the magnetic flowmeter
• Between 5 and 20 µS/cm: keep it with caution
• Below 5 µS/cm: delete the standard magnetic flowmeter

This means a magnetic meter may work well with:

• Acids
• Water
• Alkalis
• Wastewater
• Conductive slurries

But it may not work with:

• Oils.
• Hydrocarbons.
• Organic solvents.
• Very pure water.

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Mass Flow Mandatory ?

This is an important question.

Do not select a Coriolis meter simply

Because mass flow sounds better.

Ask what the process actually needs.

Keep volumetric technologies such as:

• Magnetic
• Ultrasonic
• Vortex
• Turbine
• Positive displacement
• Differential Pressure FM.

​
If calculated mass flow is acceptable:

Keep volumetric meters that can be combined with:

• Pressure measurement
• Temperature measurement
• Density measurement
• A flow computer

This can keep DP, vortex and ultrasonic systems in the discussion.

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If direct mass flow is essential ?

If yes, Move Coriolis to the front.

For suitable gas applications, thermal mass also becomes a strong candidate.

You can now delete technologies

That only provide volume (if external PT compensation is not acceptable).

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Does the fluid contain solids?

If the answer is yes,

This can weaken or eliminate:

• Vortex meters
• Turbine meters
• Some ultrasonic designs
• Positive-displacement meters

For a conductive slurry,

The magnetic meter becomes stronger because it has:

• No moving parts
• No internal obstruction
• No narrow flow path

But do not stop there.

Also check,

Whether the solids are abrasive.

An abrasive slurry can damage:

• Liners
• Electrodes
• Measuring tubes
• Internal surfaces
  

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Does the liquid contain entrained gas?

Gas bubbles can disturb several technologies.

Place these flowmeter in the caution category:

• Coriolis
• Transit-time ultrasonic
• Magnetic, (based on bubble concentration & installation)

→ Coriolis meters are excellent mass flowmeters.

But excessive entrained gas can disturb tube vibration and density measurement.

→ Transit-time ultrasonic meters also need a reliable acoustic path.

Too many bubbles can weaken or scatter the signal.

The answer is not always to delete these meters immediately.

The answer is to stop treating them as automatic choices.

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Is the fluid highly viscous?

Do not look only at viscosity.

Look at the resulting Reynolds number.

For an initial vortex screening:

• Re above 20,000: keep vortex
• Re between 10,000 and 20,000: keep with caution
• Re below 10,000: normally delete general-purpose vortex

Similarly, High viscosity can also weaken turbine performance.

For very viscous liquids, stronger candidates may include:

• Coriolis
• Positive displacement
• Specially calibrated flowmeters

Now move to the operating range.

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Filter 2: Can It Measure the Entire Flow Range?

Do not size the meter using only maximum flow.

Collect four values:

• Min continuous flow
• Normal continuous flow
• Maximum continuous flow
• Temporary start-up or design peak (If required to be measured)

Then calculate:

Suppose the flow varies from 10 to 200 m³/h.

Now begin deleting again.

Practical turndown rules
For Conventional orifice flowmeter

• 3:1 to 4:1: keep it
• 4:1 to 6:1: proceed with caution
• Above 6:1: normally delete it
• 20:1: select another technology

Why?

For an orifice:

Flow is proportional to the square root of DP.

A 20:1 flow range means the minimum flow produces only 0.25% of maximum differential pressure.

A modern DP transmitter may have impressive turndown.

But it cannot remove every uncertainty created by:

• Very low differential pressure
• Transmitter zero uncertainty
• Impulse-line effects
• Primary-element uncertainty
• Installation variation

So practical recommendation is:

If the required turndown exceeds 6:1,

Delete the conventional single-orifice system unless a complete uncertainty study proves otherwise.

Other practical turndown ranges

Use these as initial screening values:

• Coriolis: approximately 20:1 to 100:1
• Magnetic: approximately 20:1 to 40:1
• Ultrasonic: approximately 20:1 to 50:1
• Thermal mass: approximately 50:1 to 100:1
• Positive displacement: approximately 10:1 to 50:1
• Vortex: approximately 10:1, sometimes approaching 20:1
• Turbine: approximately 10:1, with higher ranges for selected designs

These are not universal limits.

They are deletion rules.

If the process requires 40:1 turndown,

• Conventional orifice
• Vortex Flowmeters

Should no longer receive equal attention.

Delete them and move forward.

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If you Want a Full PDF Guide guide on Flowmeter Selection. (With Examples)

Reply to this email with "Flowmeter Selection PDF" And I will send it to you for your future reference.

To ensure the email stays within the article limit provided by email provider.

It a long guide but super fun & pratical.

I always use this same algorithm for my selection.

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#2- Engineering Standard

Since we are discussing of Flowmeters.

The most important standard for Orifice flowmeters is

• ISO 5167

And within ISO 5167 the most important activity is "Straight Length Calculation"

Here's a Video that explains Straight Length Calculation using 3D model.

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#3 -Career Tip

I have heard experience engineers say.

I have expertise in X area.

I cannot learn Y area.

If you read biographies of the most successful people,

You will realize they had "Figureout-able MINDSET"

"Figureout-able" Mindset

This would say I dont know this but I can surely figure this out.

And they would start, GRIND.

And Wola, They did Figure it out.

I would encourage the same for you.

You will learn things you never imagined.

All the best.

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Your Feedback (Means a lot)

Your feedback means a lot (To make this articles better).

• Found Super Valuable - Reply "1".
• Found Decently Valuable - Reply "2".
• Can be improved - Reply "3".

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Want the Full PDF guide on Flowmeter Selection. (With Examples)

Reply to this email with "Flowmeter Selection PDF"

And I will send it to you for your future reference.

Sorry : I could not include the entire guide in email text itself.

but this is because the email has certain limitations on the article size.

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Until next Week,

Happy Learning and Keep Smiling.

Asad Shaikh

Your Well Wisher and Instrumentation Friend!! 😊

See you next week!