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Sewage Flow Measurement Non Intrusive In Greater Than 2 Meter Pipelines

01/12/2018 7:28 AM

The increase and advances in Tunnel Boring Machines (TBM's) and the drive to sustainability has lead to numerous mega Tunneling projects worldwide to reduce sewage pumping stations with one or two terminal pumping stations using gravity link sewers and tunnels. The available technology made flow measurement and monitoring to and from existing pumping stations easy. However it would appear technology in monitoring flows within the large 2-10m diameter concrete tunnels has not kept pace and there are no flow systems which provide flow measurement that can be installed and maintained relatively safely.

I've searched for floating pontoons/ platforms or similar which can be anchored and still allow for the variations in tunnel flow and levels.

There also appears to be no options in non intrusive fixed sensors although there are numerous manufactures of fixed sensors for pressure and velocity with level provision from other sensors.

Does anyone know of any flow system for measuring within the sewage hazardous environment which can be maintained without having to isolate the flow.

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#1

Re: Sewage Flow measurement non intrusive in greater than 2 meter pipelines

01/12/2018 7:38 AM

Investigate clamp-on ultrasonic flow meters.

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#2
In reply to #1

Re: Sewage Flow measurement non intrusive in greater than 2 meter pipelines

01/12/2018 7:43 AM

Unfortunately as tunneling there is no access to the outer diameter of the pipeline.

thanks for the speedy. response.

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#3
In reply to #2

Re: Sewage Flow measurement non intrusive in greater than 2 meter pipelines

01/12/2018 8:10 AM

Everything else fails the <...non intrusive...> criterion.

Good luck.

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#14
In reply to #2

Re: Sewage Flow measurement non intrusive in greater than 2 meter pipelines

01/16/2018 2:19 PM

Are you able to use a combination level sensor with ultrasonic flow velocity measurement to get a good approximate channel velocity and profile, then do the math for the result? Some wastewater data loggers / auto-samplers offer this feature.

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#4

Re: Sewage Flow Measurement Non Intrusive In Greater Than 2 Meter Pipelines

01/12/2018 9:22 AM

Perhaps something like this anchored to the center of a rod spanning the diameter of the pipe.

A propeller-type current meter as used for hydroelectric turbine testing.

https://en.wikipedia.org/wiki/Flow_measurement

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#5
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Re: Sewage Flow Measurement Non Intrusive In Greater Than 2 Meter Pipelines

01/12/2018 9:32 AM

Thanks yes a turbine type unit there would be potential for impact damage as the sewage is unscreened and this would provide velocity and would require a depth measurement to provide the flow rate. however there can be ways to install to protect the unit.

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#6

Re: Sewage Flow Measurement Non Intrusive In Greater Than 2 Meter Pipelines

01/12/2018 2:17 PM

OK I'll bite the unasked question, why bother to measure the flow rate of sewage in a tunnel bored pipe? One can easily measure the flow rate at the pumping stations. One can also easily measure sewage levels at many locations. I suspect the reason no easy solution exists is this flow is not needed to be directly measured.

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#9
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Re: Sewage Flow Measurement Non Intrusive In Greater Than 2 Meter Pipelines

01/13/2018 6:16 AM

If that was only the case . The pump control requires to be proactive and maintain the tunnel and wet well levels. there are up to 14 operational pumps to control and limited operational range to control the pumps to prevent surging of the flows at the down stream treatment facilities. Yes levels are relatively easy measured at many location but not so readily maintainable.

Thanks for the comments

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#12
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Re: Sewage Flow Measurement Non Intrusive In Greater Than 2 Meter Pipelines

01/13/2018 8:10 AM

Thank You for the explanation.

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#7

Re: Sewage Flow Measurement Non Intrusive In Greater Than 2 Meter Pipelines

01/12/2018 2:22 PM

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#8
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Re: Sewage Flow Measurement Non Intrusive In Greater Than 2 Meter Pipelines

01/12/2018 4:33 PM

I worked in Wastewater treatment for almost a decade. The ultrasonic or Laser will be your best bet. There have to be access and ventilation shafts periodically along the sewer so you can install those meters in those access shafts! SIMPLE!

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#11
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Re: Sewage Flow Measurement Non Intrusive In Greater Than 2 Meter Pipelines

01/13/2018 7:23 AM

Thanks for the response. Laser and Ultrasonic combination could be the answer

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#10
In reply to #7

Re: Sewage Flow Measurement Non Intrusive In Greater Than 2 Meter Pipelines

01/13/2018 7:21 AM

Thanks this looks like a good option with definite potential and will peruse further

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#13

Re: Sewage Flow Measurement Non Intrusive In Greater Than 2 Meter Pipelines

01/16/2018 4:38 AM

We have around 30 ultrasonic (through air) level sensing devices. If you already have a sewerage network, then you are probably using similar sensors in your current wet wells or measuring flow over "V" notch weirs.

Normal clamp on ultrasonic sensor need to have full pipe as most work on reflected signal and delay times. These are described as "Transit time sensors" and are unsuited to partly filled pipes.

The sensor needs some relatively simple calibration as to get flow you need not only depth, but also velocity. Velocity will not be uniform across the pipe and is not uniform for depth. Most sensor suppliers will have calibration algorithms for this.

Some others will have a sensor aimed at 45Deg upstream to monitor not only depth, but then also mid stream flow velocity.

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