Welcome to Wyatt, the DP flow specialists

A large Energy Company in Missouri experienced a failure of a 16″ insert style venturi meter after 30 years of service in a condensate flow application. The failure occurred at a Nuclear Power Plant and required immediate replacement.

Venturi meters are chosen for these applications because of their reliability and long life, so after 30 years of reliable service, a failure was unexpected.

Materials of construction were suspected to be the cause of the failure and a new approach was required. Working through the night, Wyatt Engineering supplied the power plant the next day, with an all Stainless Steel replacement meter, to the exact performance specifications of the original one.

Based on this exceptional customer service and technical expertise, Wyatt Engineering has been selected to replace all similar meters at the various power plants.

Welcome to Wyatt, the DP flow specialists

In 1961, the performance of the first and original Lo-Loss flow tubes, which were designed and marketed by the Penn Meter Company out of Philadelphia, was documented in an ASME paper, “Design and Calibration of the Lo-Loss Tube (61-WA-80).”  A year or so later, Penn was purchased by Badger Meter out of Milwaukee, and the Lo-Loss tube became the Badger Meter PMT Lo-Loss® flow tube (the “PMT” stands for “Penn Meter Tube”).  Over the years, Badger refined and developed the design, continuing to improve the PMT’s performance.  In 2001, Wyatt Engineering purchased Badger Meter’s differential-producing flow element division, sometimes called “the Tulsa operations.”  All the Badger Meter product designs and data were part of the acquisition.  In the next decade, Wyatt continued to refine the PMT Lo-Loss®, leading to an even better definition of the discharge coefficient and lower permanent pressure loss.

The Lo-Loss® was originally designed to generate a stable and high differential pressure (DP) while keeping the energy loss (headloss) low.  Classical venturi meters need a small beta ratio to produce a high DP, but the small beta ratio leads to higher headloss. This tradeoff was important because transmitters in the ‘50s and ‘60s had poor resolution and needed a large signal to achieve acceptable performance.

The Lo-Loss® was a radical departure from the traditional venturi design:  First, the high pressure tap was located at the transition from the cylindrical inlet section and the radial converging section, not some distance upstream of a converging cone as in the venturi.  Second, the Lo-Loss® does not have a long cylindrical throat, like the classical venturi, but a continuously curved transition between the inlet section and the recovery cone.   The locations of the pressure taps and the resultant meter factors were to be modified subsequent to publication of the Lo-Loss® paper because Badger CALIBRATION RESULTS REVEALED THAT THE DESIGN GIVEN IN THE ASME PAPER RESULTED IN AN UNSTABLE METER FACTOR FOR HIGHER REYNOLDS NUMBERS.  These changes in the PMT design corrected its Reynolds number sensitivity and changed the discharge coefficient, changes that have not been published or otherwise distributed.

Is this why Wyatt Engineering’s PMT Lo-Loss® is the only flow tube you should consider?  Putting it bluntly:  Yeah, pretty much.  Others do not have insight to any of the improvements made to the design in the last 50 years, including off-the-shelf software providers and common flow measurement handbooks.  The average error between that published in the ASME paper and the current state of the art is a little over 2%; the error function peaks at close to 7%; our survey of information from handbooks and calculations from flow calculating programs result in large errors relative to Wyatt’s PMT uncertainty band.  This doesn’t mean that others who have “knocked-off” the PMT can’t provide a good meter, they just can’t provide the performance you expect – or they expect – from the Lo-Loss.  Alchemists may have had “years of experience” trying to turn lead into gold, but at best, it’s fool’s gold.

What’s a poor engineer to do?  GET THE DATA.  If someone tries to sell you their “Low Loss” flow tube (or any meter, for that matter), simply ask for a summary of more than 20 flow calibration results (a random sampling) that cover a wide range of line sizes and beta ratios and that indicates the predicted coefficient and the coefficient found in the lab.  Just for fun, ask for copies of some of those calibrations, they should be from flow labs independent of the manufacturer.

Do you have questions or comments about Wyatt Engineering and the PMT flow tube?  Join the conversation here.

Welcome to Wyatt, the DP flow specialists

David Wyatt will be a featured speaker at the ISA 10th Annual Oilsands Automation Conference in Fort McMurray, Alberta, Canada. He will be presenting the paper “Flow Measurement Using Differential Producers” at 2.45 pm on Tuesday March 12th.

This highly anticipated conference has quickly become a “must go to” event for those focused on the specific needs of this specialised market.

If you are unable to make the conference but would still like a copy of the paper, please contact us.

Learn more about the conference…see you there.

 

Welcome to Wyatt, the DP flow specialists

Seven days before a scheduled start-up, a major Louisiana chemical company discovered a vital Badger steam meter had been damaged during shutdown. Desperate to restart the plant on time, they contacted Wyatt to see if we could help.

The application was a 14″ 1500# steam line that required a custom designed weld-in PMT. Working 24/7 Wyatt partnered with plant instrument personnel to lay out a plan requiring sourcing a 16″ diameter 304 Stainless Steel forging; transporting it to our facility in Oklahoma; designing and providing manufacturing drawings; precision machining the meter; and air freighting it to the Baton Rouge airport.

With manufacturing starting late Monday, the meter left the shop Wednesday by charter flight, for installation and start-up on Friday.

What is normally a multi-week cycle was reduced to a three-day turnaround.

To quote the customer:

“Just want to personally thank all of your team for helping us during this trying time!

I know we asked for the impossible, yet your team managed to meet the challenge.

I would like to add it was very gratifying to work with everyone and still maintain a high grade of professionalism.

Thank you all for your hard work,

And please share this with your other team members!”

Whether it’s an extreme expedite, or standard delivery, you can always expect this level of service from Wyatt Engineering

Five Minute Flow Measurement

Wyatt Engineering’s PMT: The REAL Lo-Loss® Flow tube
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There are a lot of companies out there that offer “Low Loss” flow tubes (or “Low-Loss” or something similar); some sales people even claim they have “years of experience” in doing so.  The fact is, only Wyatt Engineering can give you the Lo-Loss® meter with the high differential pressure and low permanent pressure loss that users have come to expect for more than 50 years… and only our PMT has meter factors that are fully documented and an accuracy that is substantiated. We have the data to prove it…..

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