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Posts Tagged ‘flow controller’

Abrasive and aggressive fluid control is difficult, but doable (Part 2)

July 24th, 2012 1 comment

In this series, we’re discussing the flow control challenges faced by users of abrasive or aggressive fluids. The first post described several applications for these challenging fluids, and briefly introduced a couple of concerns encountered by these users. In this post, we’ll review these concerns in more detail and summarize a few flow control options available for these difficult applications.

Material compatibility is a major concern when measuring the flow of aggressive fluids like acids. There are several alternatives to ensure the wetted materials in process instrumentation ‘get along with’ the process fluid. Some options include: the use of high-alloy or exotic metals like Hastelloy C, applying a chemically-resistant lining to the wetted flow path , or even using instruments constructed entirely out of chemically-resistant plastics. In addition to the instruments that provide a way to measure flow, instruments that provide a control function (like valves) should also be specified with appropriate consideration for material compatibility.

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Abrasive and aggressive fluid flow control is difficult, but doable. (Part 1)

June 19th, 2012 No comments

Here at Brooks, it’s very common for us to work with customers that use our technology in applications that aren’t widely known to the general public. In this series we’ll talk about another of these applications: flow control for abrasive and aggressive fluids. Even though the general public may not know the role that abrasive fluid flow control plays in their daily lives, applications that require this type of flow control are all around us. Many products require this type of control during their manufacturing process, and it is also used in a range of environmental applications like odor control, municipal water treatment, or pH adjustment.

There are a range of applications where reliable abrasive or aggressive fluid flow control is critical, here are a few examples:

Printing Inks: Inks used in printers that we use everyday are made from a range of fluids with different properties. Many color inks contain solvents made from aggressive petroleum distillates, and can also use dissolved titanium dioxide to control color. There are also other fluids that get mixed into these inks like: lubricants that extend the life of the printer heads, waxes that extend the life of the ink on the page, and drying agents that help the ink dry quickly onto new documents.

Slurries: A slurry is made when particles of a solid are suspended in a liquid solution. A common use for slurries is to control the flow of ‘gritty’ solid particles in the slurry across an item to polish the item’s surface, which is a critical step in manufacturing products like processors used in computers and cell phones, or solar panels. In another case, a slurry fills a mold and is turned into a brake pad after it is compressed and dried. Flow control of slurries made from suspended lime are also critical in a range of municipal, environmental, and industrial processes that treat a hazardous compound before disposal.

Metal Pickling: Pickling is a surface treatment process performed on a range of metals to remove impurities or undesirable layers on the surface of the metal. Submerging a metal part into one or more acid baths is commonly used to remove contaminants, rust, or scale to extend the life of metal parts. Pickling can also remove the oxidation layer from copper so it retains its’ color over time; this process is commonly used when making copper jewelry.

What other applications are out there for abrasive or aggressive fluids? We’d love to hear more about your applications in the comments.

As you can tell by the descriptions of these fluids, there are several challenges that users of aggressive or abrasive fluids have to overcome to be successful. Users of these fluids have to ensure that the materials of construction in the equipment and instrumentation they choose for flow control is chemically compatible with these aggressive fluids. Dissolved or suspended solids in a liquid stream can agglomerate (clump) and prevent the system from operating, so users should consider those impacts in their designs for such fluids.

We’ll discuss the range of flow control options available to users of these fluids in our next post.

If you’d like to read a bit more about instrumentation and process control, feel free to check out more of my contributions summarized on my Google Plus profile.

Video: How a single mass flow controller can do the job of ten others

May 17th, 2012 No comments


 

Thermal mass flow controllers are traditionally calibrated for a specific gas, a desired flow range, and a set of operating conditions. Over time, the use of conversion factors based on a ratio of specific heats between gases came into use as a way for users to configure a single mass flow controller for multiple gases. This method of configuring a mass flow controller for multiple gases is still common today – you’re using it if your device lets you select a gas by: rotating a knob, pressing a button on a display, or sending an RS232 command to the device.

Accuracy is the primary issue with this method of conversion. Converting flow rates between the calibration gas and another gas based on a ratio of specific heats can result in a mass flow control error of 5-6%. This error is the result of the conversion method because it ignores other property differences that exist between gases in the real world. If you’re changing the gas on your device with one of the actions above, ask the manufacturer of your mass flow controller what the accuracy of the device is for a gas other than the calibration gas.

P.S. If you’re told that such a device is linear in all the available gases and thus the mass flow accuracy doesn’t change when the gas is changed, RUN! This is not physically possible. Feel free to contact us for comparison data.

Multiflo by Brooks Instrument is a leap forward in configuring a mass flow controller for multiple gases because it converts based on gas differences in specific heats, densities, and viscosities. Multiflo-Capable mass flow controllers cut the conversion flow control error in half compared to devices that convert gases based on a specific heat ratio alone.

This video demonstrates how a Multiflo configuration is performed on a mass flow controller. We welcome your thoughts or questions in the comments below.

You can find more information on Multiflo-Capable mass flow controllers on the Brooks Instrument LinkedIn company page. Your local Brooks product expert would also be happy to help you configure a Multiflo-Capable mass flow controller for your applications using the information entered on this form.

If you’d like to read a bit more about instrumentation and process control, feel free to check out more of my contributions summarized on my Google Plus profile.

Flow control problems when backpressure changes? Choke the flow! (Part 2)

April 25th, 2012 No comments

In my last post, we discussed several applications for mass flow controllers where precise flow control is needed despite backpressure changes. I introduced a flow effect called choked flow, which many of our customers use in these applications to ignore downstream pressure changes. This is also referred to as sonic flow or critical flow.

To my flow-savvy readers: You’ll notice that I’m discussing choked flow in conceptual terms rather than demonstrating complex formulas and calculations. Don’t be alarmed! Feel free to post any additional thoughts you have on this topic in the comments below.

The sketch to the right shows gas flow through a typical orifice. The green shaded areas are high pressure, low velocity flow areas, and the blue area is a low pressure, high velocity flow area. Inlet gas flow speeds up as it compresses to pass through the orifice, then re-expands and slows back down on the outlet side. The flow rate through the orifice is primarily set by the inlet and outlet pressures, as well as the diameter of the orifice opening. Gas temperature also plays a part.

A gas expands in a space as its molecules collide with whatever else is present. (pipe walls, other gas molecules, etc.) Every gas expands at its own rate, and pressure increases in a gas are a result of squeezing more gas molecules into the same amount of space. Applying these factors to the orifice flow pictured, gas expansion causes some of the molecules that are expanding in the green area on the outlet side to collide with and deflect the “fast” molecules in the blue area. If the pressure rises in the green area on the outlet side, it’s because there are more gas molecules present in the same amount of space.

More molecules in the green outlet area mean that more molecules deflect the “fast” molecules in the blue area. This reduces flow velocity in the blue area, which is what reduces the flow rate passing through an orifice at higher backpressures. If the pressure drops in the green outlet area, it means that fewer molecules are present in that space, which results in fewer deflections of “fast” blue molecules. This causes a higher velocity in the blue area, and thus a higher flow rate when the backpressure drops.

Choked flow occurs when the flow velocity in the blue area reaches the speed of sound. At this velocity, the molecules in the blue area are essentially traveling faster than the molecules in the green outlet area are expanding. So deflection between molecules at the blue/green border doesn’t reduce velocity in the blue area. With a fixed inlet pressure, the outlet pressure can change over a wide range without changing the mass flow rate as long as the conditions to maintain choked flow remain in place.

So how can we reach the conditions needed to maintain choked flow? We’ll cover that in our final post in this series.

Where did the names choked flow, sonic flow, and/or critical flow come from? Please post where you think one of these names came from in the comments. The first poster that correctly lists the reason for each of the names will win a 4 GB jump drive in the shape of a mass flow controller.

If you’d like to read a bit more about instrumentation and process control, feel free to check out more of my contributions summarized on my Google Plus profile.

#Pittcon – Here We Come!

March 9th, 2012 No comments

Next week is the Pittcon trade show. Boy, that came up quickly! If you are planning to head to Orlando, FL for Pittcon this year, be sure to stop by and see us at booth 961. In fact, click here if you want to schedule an appointment with one of our sales engineers at the show! If you do stop by, you’ll be able to check out our award winning products like the brand new GF40/80 Series mass flow controller / mass flow meter, the XacTorr Series capacitance manometer, SolidSense II pressure transmitter, and so much more!

Just so you know what to look for on the show floor, below is a picture of our booth. So be sure to hunt us down at Pittcon. We’d love to hear from you!

Guess What Year This Flow Meter Was Made

December 19th, 2011 60 comments

Last week a co-worker of mine was cleaning out some old marketing demos and found the beauty pictured below. This is an old Full-View variable area flow meter. We took guesses amongst ourselves as to what year this was manufactured. The product manager, Jim Dillon, had to find out. So he went and pulled technical microfilm … that’s right, I said microfilm! It took a a few days because the machine to read the microfilm needed a new fuse. This was turning into quite the project!!! Well … we found out the year. You can see the order form pictured below. I blocked out any indication of what year this was produced. Can you guess?

Take a guess before the year is through (deadline is 12/31/11) and the first ten (10) responders that guess the correct year this product was produced will win a 4GB memory stick shaped like our new GF40/80 thermal mass flow meter/mass flow controller.

New MultiFlo Capable Mass Flow Controller & Flow Meter

December 13th, 2011 1 comment

This has been a product that we have been working on and perfecting on over the past several months and I’m extremely excited to finally formally launch the new GF40 and GF80 thermal mass flow controller and flow meter! These mass flow controllers provide outstanding performance, reliability and flexibility in many gas flow measurement and control applications. One of the best features of this new mass flow controller is the patented 4th generation MultiFlo gas and range configurability. MultiFlo programming is simple and fast – a new gas and range can be programmed under 60 seconds plus the device can be programmed without removing it from service or disconnecting the device from any process or tool control system.

The GF40/GF80 Series mass flow controllers features fast sub one second settling times and corrosion-resistant Hastalloy sensor tube for long-term stability. The superior valve technology provides minimum leak-by, maximum turndown and fast response which reduces overall gas panel cost and increases throughput. Additionally, the measurement accuracy of every device is verified using traceable primary calibration standards.

Want to learn more? Download the datasheet or contact your local sales engineer.

Brooks’

New Product Guide is Complete!

November 10th, 2011 No comments

I’m personally very excited to present to everyone our brand new Brooks Instrument product guide. Updated with all of our latest and greatest products like the GF40/80 mass flow meter / mass flow controller, XacTorr vacuum capacitance manometer, SolidSense II pressure transducer/transmitter, pressure gauges, LF200 ultrasonic liquid flow controller, and more. I won’t bore you with a long blog post about this product guide, just download it and check it out instead!

Fuel Cell Seminar and Chem Show Ramblings

November 8th, 2011 No comments

Well, last week sure was a busy one for Brooks with two major trade shows going on for us at the same time. We had the Fuel Cell Seminar in Orlando, FL and the Chem Show in New York, NY last week. I personally attended the Chem Show in NYC. The show was much smaller than in years past but we still made some good contacts and spoke with a lot of customers searching for flow meters and flow controllers. Not to mention our direct liquid injection vaporizer system. I always find it humorous that our magical floating ping pong demo attracts so much attention. It’s so simple yet everyone loves to stop and see how we are using our 4800 Series mass flow controller and 1355 Sho-Rate flowmeter to levitate a ping pong ball in mid air! Read more…