Flow Meter Installation Question 1

[okuo]

First thanks for the help. I'm quite new in industry so this could be a very basic question.. I tried searching but couldn't find anything

But I'm planning to install a flow meter for our process and from the flow meter manufacturer it appears that the sizing of the meter is smaller than the piping we currently use / they don't have available sizes for the accuracy that we would require. So, a section of piping would have to replaced (I found the rule of thumb to be 10D upstream and 5D downstream for flow meter "true readings") so the piping to be installed will meet this.

I'm just unsure how to install the PVC piping, the flow meter is a flange connection so it will be connected in that regard with the 10D / 5D on both sides that way with the appropriate pipe but then how will those 2 sections of pipe with the flow meter be installed in the existing line? There are expansion or compression joints correct? What else do I have to consider for this.

 

[bimr]

One assumes that you are referring to smaller diameter piping.

The typical practice is to use PVC flanges that are solvent welded onto the PVC pipe. PVC piping is typically joined with solvent welding. Bolt the PVC flanges to the flowmeter.

If you are using pipe reducers, don't install the pipe reducers adjacent to the flowmeter. Install the reducers outside of the 10D upstream and 5D downstream pipe segments.

 

[okuo]

Hi bimr, yes the piping we have is 3/4” CPVC and the flow meter will be 1/2” and the flanges of the flow meter will be made out of SS coated with TFE.

Sorry if this is a dumb question but is it okay to connect the PVC flange to the flow meters SS flange like that?

Thanks again

 

[danw2]

The upstream/downstream requirements are technology dependent. You should read the manual for your flow meter to get recommended upstream/downstream requirements and not rely 'rule-of-thumb'. Specifically, Vortex meters require a lot more flow conditioning and more upstream straight run than mags or DP.

 

[bimr]

Depending on the situation, the transition can be made using flanges, threaded fittings or unions. The same type of flange has to be used so the flanges match.

•Flange connections are limited to 150 psi.
•Threaded connections are limited to 50% of the rated pressure of the pipe.
•When mating to a threaded metal piping system, it is recommended that a plastic male thread be joined to the metal female thread. Since the two materials have different co-efficient of expansion, the plastic male fitting will actually become tighter within the female metal fitting when expansion occurs


Review the Corzan brochure:

Corzan

 

[okuo]

Danw2, will do! Thanks for the suggestion.

Bimr, that brochure is really helpful and answered my questions. Thanks again for the help.

 

[zdas04]

You are getting a lot of advice with all of the responder's actually guessing about the measurement technology and fluid you are using. I would expect a different answer depending on the technology and fluid in your process. You could be using a wafer V-Cone and simply weld on two PVC flanges. On the other end of the spectrum if you were using a Coriolis meter you would need to put about a joint of steel on either side of the meter to prevent the flexing of the meter from breaking the PVC. Other technologies, other answers. Be very wary of people who provide answers with the kind of information you provided in your original post--you can be confident that they are simply making stuff up to fill in the huge gaps in your original post.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[bimr]

"However, some flowmeters have upstream straight-run requirements that are independent of the upstream piping configuration. For example, magnetic flowmeters typically require 3-5 diameters of upstream straight run, while positive displacement, Coriolis mass, proprietary magnetic, and proprietary differential-pressure flowmeters do not have any straight-run requirements." "The straight length of pipe for the vortex meter must be the same size as the meter."

Upstream Straight Run Piping Requirements

When 10D straight run calculates to just 5-Inches, one would be splitting hairs to expect a different answer. The rule of thumb that you have proposed is conservative.

"Deposits and strong vibration can degrade accuracy. Newer Coriolis flowmeter designs, however, resist normal pipe vibration if the surrounding process piping properly supports the meter. No special supports or pads are needed for the flow tube. If the installation instructions require special hardware or supports, the meter design is likely to be sensitive to vibration."

Flow Meter Piping Requirements

The typical 3/4 Inch Corzan CPVC pipe installation should have pipe supports every 5 feet when operating at 100^oF to avoid pipe sagging. Standard piping supports are adequate to support any type of 1/2 Inch flow meter. Each side of the flow meter should have a pipe support located outside of the piping flange.

Corzan Pipe Supports

Suggest you review the Flow Meter Piping Requirements article and the manufacturer's installation manual in the event that something has not been discussed.

 

[SandCounter]

Make sure you check losses through the flow meter and ensure they do not negatively affect the system. I have gained very expensive experience learning not to go on flow meter manufacturer's assurances that they "always go a size smaller" and that "they've never had a problem in the past."

I used to count sand. Now I don't count at all.