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Rasika Deval
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Join Date: Feb 2013
Posts: 4

Flow Meter For Instantaneous Air Flow, India

02/04/2013 12:38 PM

Which type of flow meter will be suitable for measuring air flow to ROV line.

We need to install flowmeter in line supplying air to operate remote operated ball valves.There are some 10 remote operated valves, about 100cc nitrogen gas is required to operate the valve, operating cycle is 2 to 3 sec, Line size - 1", can be reduced as per design requirements.
Is rotameter/thermal mass flow meter a suitable option, based on response time since frequency of operating these valves is very low, I need totalized value on PLC.
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Iris
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#1

Re: Flow Meter For Instantaneous Air Flow, India

02/04/2013 2:06 PM

Whether a thermal mass flow meter is fast enough depends on its reponse time, which is dependent on the specs for a given brand and model. Thermal dispersion meters are an excellent meter choice for clean dry gas.

Do you really need a flowmeter? You might consider that automobile fuel consumption on gasoline fuel injected engines is calculated by monitoring the time duration that each injector is open and adding up all those time intervals and then multiplying by the K flow factor for that engine's injectors.

In your case, if each cycle is 100cc (or whatever) of nitrogen, just count the number of operations to obtain the total. Why measure flow if you can use a counter in the PLC?
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Ried
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Join Date: Dec 2005
Posts: 1602
Good Answers: 19
#2
In reply to #1

Re: Flow Meter For Instantaneous Air Flow, India

02/04/2013 11:08 PM

GA, answer meets K.I.S.S. principle quite nicely!

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Rasika Deval
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Join Date: Feb 2013
Posts: 4
#7
In reply to #1

Re: Flow Meter For Instantaneous Air Flow, India

02/05/2013 11:40 PM

Though using a counter in PLC seems to be a best option,I need to give a flowmeter as per the contract.There is a pressure transmitter in the line already.Thank you for the suggestions, needed to confirm before going to the vendors.
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Deefburger
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Location: Sebastopol, California
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#3

Re: Flow Meter For Instantaneous Air Flow, India

02/05/2013 12:33 AM

You could use a ping pong ball in a glass tube and run the flow up. Great visual and you can also tell how many valves are open at a time by the height of the ball in the tube. But for practical purposes, do the calculation method in the PLC like Iris said!

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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
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#4

Re: Flow Meter For Instantaneous Air Flow, India

02/05/2013 3:40 AM

Try using a variable-area flowmeter in a pipe where the flow is vertically upwards.

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instrumentman35
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#5

Re: Flow Meter For Instantaneous Air Flow, India

02/05/2013 5:49 AM

Why even use a flow meter. Use a pressure switch in the line. As soon as there is pressure in the supply the valve must be open supplying the appropriate flow.
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PWSlack
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#6

Re: Flow Meter For Instantaneous Air Flow, India

02/05/2013 6:34 AM

Count the valve openings and multiply that number by the air consumed each time.

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Rasika Deval
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Posts: 4
#8

Re: Flow Meter For Instantaneous Air Flow, India

02/05/2013 11:42 PM

Though using a counter in PLC seems to be a best option, I need to give a flow meter as per contract.Thank you for suggestions,needed to confirm before going to vendors.
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Ried
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Posts: 1602
Good Answers: 19
#9
In reply to #8

Re: Flow Meter For Instantaneous Air Flow, India

02/08/2013 9:49 AM

What will your customer do with the flow meter? Does the customer need a total flow measurement or and instantaneous flow rate?

Did the customer specify a specific type or style of flow meter?

Keep asking questions, then base your design on the knowledge you get from the answers.

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Rasika Deval
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Posts: 4
#10
In reply to #9

Re: Flow Meter For Instantaneous Air Flow, India

02/08/2013 11:00 AM

Consultants have asked for a DP transmitter and need a instantaneous output as well.
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Ried
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Join Date: Dec 2005
Posts: 1602
Good Answers: 19
#11
In reply to #10

Re: Flow Meter For Instantaneous Air Flow, India

02/08/2013 11:50 AM

As a consultant, I can say that we do not always know what we are doing. Sometimes we do. If you ask specific questions, you might get clarification of what they need vs. something that sounds nice but is not a realistic goal. Trying to make instantaneous flow rate readings on a pulsating flow seems to be a difficult task, and without more information, I do not see the value of such measurements.

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11 comments

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Users who posted comments:

Deefburger (1); instrumentman35 (1); Iris (1); PWSlack (2); Rasika Deval (3); Ried (3)

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