Like Oil and Water, and Ethylbenzene?

Chemical Resistance Compatibility

Tips From the Service Bench

Technology TIP

When pumping liquids, you must be sure flow path wetted materials are compatible with intended media. If not researched and tested, issues may arise in the field that may impact product life and maintenance schedules.

While Chemical Compatibility Charts are a good place to start your research, there is typically a standard disclaimer at the bottom that limits their application and places the responsibility on you the buyer, such as:

Warning: The information in this chart is to be used as a guide, ONLY. Although believed to be accurate, actual decisions on material selection need to be thoroughly tested and evaluated by the customer for each specific application. It is the full responsibility of the customer to perform and evaluate the compatibility of materials for their specific requirements. The manufacturer takes no responsibility, etc., etc…


ARE WE COMPATIBLE?

Polymer components exposed to incompatible media can experience swelling or loss of physical properties. When severe, these effects can lead to degradation of pump performance, reduced pump life, leakage, and even pump failure. These issues are avoided with proper material selection. Many pump manufacturers provide a selection of flow path materials to meet most needs, and some provide additional material options for exceptional cases.

TESTING OUR RELATIONSHIP

So, how do you go about testing chemical compatibility? You can get test swatches of possible polymer materials. But, results using test swatches can be less than applicable since they may be much thinner or thicker than the actual parts used in pumps. KNF offers a better way to assist your compatibility decisions, with our Chemical Resistance Test Kit (p/n 173610). This kit contains our most popular head plates and elastomer valves materials. These are actual production parts in current use, so they offer the best test subjects possible. For each material, two parts are supplied – one for resistance testing, the other as a comparison reference. Simple instructions will guide you through the static soak test process.

Chemical Resistance Kit Materials

Kit materials: (1) PEEK (2) PPS (3) PVDF (4) PP (5) FFKM-A (6) FKM (7) EPDM (8) FFKM-B (9) FFKM-C

SUMMARY

In a typical fluidic system, component lifetime will be influenced by several variables beyond simple compatibility of the liquid media, including chemical concentration, liquid temperature, operating pressure, flow rate, and exposure to abrasive materials. A static soak test cannot, therefore, replace a long-term validation test with a pump running in a real system under system parameters. But, a static soak test is well suited as part of an initial screening to identify and eliminate materials which are clearly incompatible with expected liquids.

Contact KNF today for a Chemical Resistant Test Kit and get pumping with confidence!

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Thread Seal Tape, a Fitting Friend

Tips From the Service Bench

By design, vacuum pumps pull gas or liquid in on the inlet side and expel media on the exhaust side. One prevalent issue to avoid, in order to ensure that the pump keeps operating to full potential, is keeping unwanted material out of the pump head and valves.

Many vacuum pump plumbing connections are made with hose connectors and fittings. One standard fitting thread is the National Pipe Thread (NPT). The threads on an NPT fitting are tapered for sealing, and are often used with a thread sealant, such as Thread Seal tape.

A recurring issue seen by our Service Department is loose Thread Seal tape unintentionally ingested into a pump (see photos below). The loose tape gets pulled in by the vacuum and lodges between the valve and valve seat. This can result in a loss of performance in the system and headaches for the pump user. The cause of this reduced performance is often not readily apparent, either.

Figure 1: Actual photos of ingested Thread Seal tape found within pump heads.

Once ingested, tape will not be expelled on its own as the path through the pump head is not designed to allow long/stringy solids to move through it. The removal of the tape debris involves disassembly of the pump head assembly, removal of the tape and re-assembly after inspection of all the components. This is time consuming and can be avoided.

One way to avoid ingested Thread Seal tape is to understand how the tape works in conjunction with the fitting and threaded port hole. The taper on NPT threads allows them to form a seal when torqued, as the flanks of the threads compress against each other. The fittings seal on the actual thread of the fitting and the hole. The fitting does not necessarily have to be installed to full thread depth as it is sealing on the thread itself.

DO’S

Figure 2: Apply Thread Seal tape

• Wrap the tape clockwise (facing the threaded portion) so that it follows the direction that the fitting will be threaded into the port (see Figure 2). Winding the tape in this direction will prevent the tape from unwinding during the tightening process.

• Use a Thread Seal tape that is narrow enough so it does not cover the first two threads of the fitting (see Figure 3). The first of the male fitting threads are the smallest in diameter and any tape wound onto these threads may actually be cut off as the fitting engages. The cut off tape may then be pulled into the pump head by the gas or liquid flow.

Figure 3: Correct application of Thread Seal tape

• Use 2-4 wraps of Thread Seal tape. You may need to adjust the number of wraps due to specific tolerances.

• Start the fitting by hand to ensure no cross threading occurs.

• Tighten according to fitting manufacturer specifications.

DONT’S

Figure 4: Incorrect application of Thread Seal tape

• Don’t wrap the tape covering the bottom of the fitting. Leave two threads free of tape (see Figure 4).

• Don’t feel the need to tighten fitting until the hex is flush. The sealing occurs on the tapered thread. It is OK if a few threads are left visible as long as the fitting is tightened to the manufacturers specified torque.

WRAP UP

Learning to apply Thread Seal tape properly will serve you well. When used properly, Thread Seal tape is a wonderful sealant. It is inexpensive and works in many different applications. It is easy to apply and lubricates the fitting and threaded hole assembly process. It also prevents possible corrosion at this interface and aids fitting removal.

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New Flow-Tight, Diaphragm Liquid Transfer Pump Prevents Uncontrolled Flow

New, FL 10 Diaphragm Liquid Transfer Pump Prevents Uncontrolled Flow

KNF’s newest liquid transfer pump, the FL 10, is leak-tight in both directions, preventing uncontrolled flow and back-flow of liquid media when not in use. The latest addition to KNF’s extensive line of diaphragm liquid transfer pumps, the FL 10 offers many advanced features, and provides a considerable advantages over similar competitive products.

Leak-tight Diaphragm Liquid Transfer Pump

Featuring a solenoid-drive, and leak-tight valve technology, the compact FL 10 liquid transfer pump displaces fluid at a flow rate of 0 – 100 mL/min. Additionally, a signal frequency modulation feature enables quick and easy flow rate adjustments, saving time and money. Finally, like all KNF diaphragm liquid handling pumps, the FL 10 is self-priming, dry-run safe, and maintenance-free – offering outstanding performance longevity and an extraordinarily long service life (10,000 hours or 1.8 billion strokes).

To learn more about the leak-tight FL 10 liquid transfer pump visit knfusa.com/FL10

College Students Use KNF Pumps to Fuel Racing Success

Wisconsin undergraduates have a need for speed.

Students from the Milwaukee School of Engineering (MSOE) have been getting in the competitive spirit in an effort to create and race the most energy-efficient cars.

Consisting of undergraduates ranging from freshmen through juniors, these students are part of their university’s Society of Automotive Engineers (SAE) branch. As the organization operates solely on outside funding, KNF has sponsored these adventurous and ambitious students in their racing endeavors through the donation of needed liquid diaphragm pumps.

Joe Pechstein and team pose for a photo at the Shell Eco-marathon flanked by their vehicles.

Overseen by project manager Joe Pechstein, a junior, the group participates in two annual events: the Shell Eco-marathon, which took place in April 2017, and the SAE Supermileage competition, which took place in June 2017. Continuing an almost ten-year tradition of entering these selective competitions, Pechstein supervises the building of two vehicles for the former competition and one vehicle for the latter.

The mechanical engineering major recognizes the challenges involved, stating that the race is “a test of the driver’s skill, the design’s endurance, and the design itself.” With all design and testing done by students, the competitions represent the future of motor engineering.

To get the highest fuel economy possible while still meeting lap times, these twenty-five students use KNF’s NF 1.25 RPDC for their fuel system. These compact and powerful KNF pumps are used for engine dynamometer testing which typically determines the torque or power characteristics of a machine under test. Though dynamometers can also be used for standard emissions testing cycles such as those defined by the United States Environmental Protection Agency. The vehicle itself is a three-wheeled device with optimal aerodynamic features. Convenient in its small and lightweight design, the KNF pumps allow for an appropriate pressure range and high enough fuel output to guarantee full speed ahead.

A photo of the course which is usually a motor racing track or a closed off city street.

How did these students fare in the competitions? At the Shell Eco-marathon, the gasoline vehicle came in 14th place out of 30 at 588 mpg, while the electric vehicle came in 9th place out of 17 at 120 mi/kwh. Having made their mark in the gasoline vehicle category, Pechstein admits that “we have been steadily improving our fuel economy over the past three years.” In the SuperMileage competition, they came in 8th place out of 16 at 442 mpg, and an impressive 3rd place in their design report. Of KNF’s contribution, Pechstein adds that “the pumps were ideal” in helping to reach the finish line.

The team at KNF offers our congratulations to MSOE’s Society of Automotive Engineers! We know they have a bright future ahead.

Is It Time To Replace Your Water Aspirator?

A water aspirator is a simple device capable of creating a low strength vacuum for many standard laboratory applications. Though they are inexpensive to purchase and easy to use, the long-term operating costs and environmental impact of laboratory water aspirators can be quite significant.

The above video from Lab Manager follows Linda the Lab Manager as she and her colleagues investigate the real costs of owning and operating a laboratory water aspirator.

The Bear, The Pump, and Three Forks: A Tale of Sabotage Near Godfather Lake

From the time KNF was founded, “durability” has been one of the most distinguishing traits of our pumps. We feel a strong sense of pride whenever our customers use adjectives such as: “strong”, “enduring”, and “tough” when describing our products. That said, there are rare occurrences when a KNF pump succumbs to unusually extreme punishment. Not too long ago, a KNF customer, Brian Jarrell, informed us of one such example.

Brian is the Recreation Director at The Lodge and Spa at Three Forks Ranch, a luxury Resort and Spa approximately 40 miles north of Steamboat Springs, Colorado. The sprawling, 50,000-acre resort offers beautiful landscapes, scenic mountain vistas, various year-round activities, and upscale amenities. As part of his duties, Brian is responsible for maintaining ponds and other natural features across the huge property. To that end, many bodies of water around The Lodge, including nearby Godfather Lake, are equipped with solar-powered aeration systems. These aeration systems employ KNF N 828 gas pumps to inject air into the water for improved clarity and quality. When Brian needed help with his system’s pump, he called KNF and told us his wild story of a shaggy saboteur.

A visitor admires the wildlife & natural beauty of Three Forks Ranch (photo via threeforksranch.com)

One day, while making his usual checks around the property, Brian approached a pond to find that the nearby aeration system was completely silent. As he examined the control box, it became evident that the protective cover had been completely ripped off. According to Brian, a large black bear – 7 feet tall and 450 pounds – had destroyed the cover protecting the aeration system’s electronic components. As bad luck would have it, heavy snow soon fell over the exposed electrical components of the system, short-circuiting one of the two KNF pumps inside.

These circumstances are certainly extraordinary, and even frightening considering that a huge bear was probably lurking nearby while Brian was examining the damage from only a few hours earlier. However, according to Brian, scenarios involving wild animals are nothing unusual in his line of work. “We have had animals destroy our property in the past – problems with elk and bear chewing wires.” Brian calmly elaborated, “They are typically searching for food when they stumble onto a piece of equipment and become very curious. This bear may have been bored and was likely looking for something to do.” Well it certainly appears that this bear found something to do! On the bright side, this was the very first incident involving aeration systems on the property. Prior to the curious and destructive bear, both system and pump were “running just as strong as when they were originally installed” in 2004.

The suspect: Ursus americanus aka American Black Bear

The suspected saboteur: Ursus americanus (aka American Black Bear)

After finding the mauled machine, Brian soon contacted a KNF Technical Sales representative and, after a “painless and easy” conversation, he was on his way to receiving a replacement pump. When asked about the required repairs, Brian seemed almost relieved, “The whole thing was taken care of within a matter of hours. I am very appreciative of KNF”. In fact, he rates his experience with KNF a 10 out of 10. We’re glad to know that Brian’s experience was  positive, and we hope that the local black bear population seeks entertainment elsewhere in the wilds of Colorado.

Former MythBuster Delivers Keynote at Pacific Design & Manufacturing Event

Former MythBuster Jamie Hyneman at Pacific Design & Manufacturing

Jamie Hyneman, former MythBuster, speaking at Pacific Design & Manufacturing event (source: Pinterest)

This year, guests of the recently re-branded Pacific Design and Manufacturing event received a special treat as Jamie Hyneman – the famed, former co-host of The Discovery Channel’s popular television series, “MythBusters” – delivered the keynote speech. During his speech, Mr. Hyneman communicated the value of hard work, and also referenced the importance of constant improvement through his own love of tinkering. The honorary Doctor of Engineering stated, “Science isn’t done by people in lab coats. It is done by people that want to do a good job at figuring something out”. With talk of science and tinkering, it is no surprise that the 2017 keynote speaker was able to connect with his audience. After all, there were thousands of engineers in attendance of the annual conference, most of whom share a love of tinkering.

Though Jamie Hyneman has since moved on from Myth Busters, and The Discovery Channel has stopped production of new episodes, it has not stopped millions of fans from holding the show in high regard for its creative and courageous (often crazy) engineering. For example, many at KNF recall an episode that first aired on July 12, 2006 titled, “Crimes and Myth-Demeanors (part 1)“. During the episode, the crew attempt to debunk robbery and break-in scenarios so often depicted in Hollywood movies. Things get interesting when Jamie Hyneman and co-host Adam Savage begin development of their own gadgets: super-magnets, and suction cups, respectively. The peculiar devices were custom-engineered to assist the show hosts with an air duct climb).

KNF N 828 vacuum pump

KNF N 828 vacuum pump

What makes this episode particularly memorable to KNF USA associates is the vacuum source used for Adam’s suction cups – a KNF N 828 Diaphragm Vacuum Pump! The lightweight, oil-free KNF N 828 vacuum pump performed admirably to spec, pumping to 100 mbar of absolute vacuum via the suction cups on Adam’s hands and feet. However, in the end, both co-hosts were unable to climb the flimsy air duct without considerable noise, thus being anything but stealthy. Another Myth Busted. Later in the episode, Adam used his KNF N 828 vacuum pump powered suction cup rig to climb eight stories up the outside of a glass building before becoming too exhausted to continue. But not before further demonstrating the power of the KNF N 828 diaphragm vacuum pump!