New Kids on the Block

TIPS FROM THE SERVICE BENCH

Phillips and Allen have dominated machine, sheet metal and cap screws for a long time. They are popular, easy to use and easily recognizable. But Phillips and Allen are looking over their shoulders! There are a couple of New Kids on the Block!

The new kids’ names are Torx and Pozidriv. The names may sound foreign but they fit right in the machine screw neighborhood. More surface area and better geometry make these screws more resistant to cam-out — or stripping — as it is more widely known. KNF is still utilizing Phillips and Allen head screws but Torx and Pozidriv are definitely making their presence felt.

TORX

Figure #1 (click to enlarge)

Torx are called “star drive” by some, as the recess resembles a 6 pointed star. The six points of contact engagement allows for higher torque being applied than a conventional Allen hex drive of the same size. Torx sizes are denoted by a T, followed by a number from 1 to 100. Common sizes used for KNF products include T6, T10, T15, and T25.

Various Torx screws and drivers are depicted in Figure #1 (left); shown clockwise (from top-left): various Torx screw heads, Torx handles, Torx driver, Torx black & white image.

POZIDRIV

Figure #2 (click to enlarge)

Pozidriv screws are almost a cousin to Phillips. The Pozidriv (sometimes spelled incorrectly as “Pozidrive”) is actually an improved version of the Phillips screw drive. The name is short for Positive Drive. This screw recess is very easy confused with Phillips if not noticed. Using a Phillips driver for Pozidriv screw recesses can easily result is a stripped head due to the different geometry of the driver itself. The Pozidriv has additional ribs in the driver tip which are received by the secondary web of the Pozidriv screw itself. This extra feature provides more turning strength due to the higher tool engagement. Figure #2 show various Pozidriv screws and drivers; shown clockwise (from top-left): Pozidriv screw heads, Pozidriv handles, Pozidriv driver, black & white image of Pozidriv.

Pozidriv drive bits are designated by the letters “PZ” plus a size code of 0, 1, 2, 3, 4 or 5. Common at KNF are the 0, 1, and 2 sizes. The drivers themselves will have a PZ marking and size code, and possibly the Pozidriv image on the handle butt.

The Pozidriv screws are visually distinguishable from Phillips by a set of radial indents set at 45° from the main cross recess on the head of the screw. These markings are sometime hard to see on plated or treated screws as the treatment may fill in the slighter 45 degree markings.

Please take care to look at these screws carefully before removing for service. Using the right driver will make your servicing quick and efficient. If you are in doubt of which screw is used on your KNF pump, please contact us. We are here for you.

WELCOME TO THE NEIGHBORHOOD

They don’t make things the way the used to, and this can be a good thing, since the latest tools usually incorporate technological advances that improve performance. Please give the “New Kids on the Block” a chance, they are proving to be hard workers!

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100,000 Hours and Counting!

On February 4, 2005, KNF USA engineers entered the temperature-controlled space of the “Life Test Room” in Trenton, NJ to initiate prototype testing for a specially-modified version of the KNF N 838 series diaphragm pump. At the time, the custom-designed OEM vacuum pump was being developed for a Fortune 100 medical device manufacturer, as an integral component of their immunoassay and clinical chemistry analyzer. The KNF pump would need to perform its duty – vacuum aspiration of biological samples – quickly and quietly, while ensuring precision and durability over the life of the pump. Like all spec-driven KNF project pumps, the custom-engineered N 838 vacuum pump was to undergo substantial testing to ensure accuracy, reliability, and overall quality.

KNF Life Test Room

A peek inside the carefully controlled conditions of KNF’s Life Test Room

Among all tests performed by the KNF R&D team, the Life Test may be the most valuable as it simulates the rigorous operating conditions often found in real-world environments – providing valuable data which is used to further improve pump performance. KNF pumps that undergo this particular test are operated under a continuous duty cycle, at high load, in unfavorable temperatures. Collectively, these test settings amount to what KNF Engineers use to determine a “worst case scenario”. In short, the Life Test is employed as a means to identify specific opportunities for improvement, while simultaneously gauging the life span of the pump in its current configuration.

The specially-modified version of KNF’s N 838 diaphragm vacuum pump has been running in a controlled test environment since Feb. 4, 2005.

Remarkably, from the date this post is written, over 12 years (105,189 hours) have passed since Life Testing began for this special N 838 project pump. You read that correctly; the incredibly durable N 838 pump is still running strong after more than a decade! This impressive test run time represents the longest continuous duty timeframe ever recorded at KNF Neuberger. It should also be noted that this record-setting operating life was achieved with only a few minor updates including diaphragm replacements at 30K and 60K hours. Despite advancements in both pump technology and testing procedures, engineers at KNF will continue to operate this extraordinarily resilient pump, in the Life Test Room, until it has completed a full lifetime…whenever that may be.

To put this unbelievable achievement into perspective, we have compiled a list of historical events* that have occurred since the start of the N 838 project pump Life Test:

  • 2005 (Aug) – Hurricane Katrina makes landfall, devastating the US Gulf Coast
  • 2006 (Jul) – Twitter is launched
  • 2007 (Jun) – Apple releases the iPhone
  • 2008 (Nov) – The United States elects Barack Obama president
  • 2009 (Jul) – Roger Federer wins record 15th grand slam at Wimbledon
  • 2010 (Oct) – All 33 Chilean miners are rescued after being trapped for a record 69 days underground
  • 2011 (Apr) – Fidel Castro resigns from the Communist Party of Cuba’s central committee
  • 2012 (Nov) – Scientists detect evidence of light from the universe’s first stars
  • 2013 (Jul) – Detroit, Michigan becomes the largest U.S. municipality to file for bankruptcy
  • 2014 (Mar) – Malaysia Airlines flight 370 disappears kicking off the most expensive search effort ever
  • 2015 (Oct) – China announces the end to their one-child policy after 35 years
  • 2016 (Nov) – Donald Trump is elected President of the United States
  • 2017 (Jan) – World’s largest dinosaur footprint (1.7 meters) found in Western Australia

* events chosen, at random, from www.onthisday.com

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.