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Why Do Sanitary Mechanical Pump Seals Fail?

December 5, 2014
Mechanical Pump Seals

Sanitary Pump Mechanical Pump Seals

We sell a lot of sanitary pumps and almost all of those pumps have some type of mechanical seal.  We’ve talked a lot about seals on this blog in 2014. The mechanical seal in a sanitary pumps separates the “clean” process from the “dirty” outside world. Failure of the mechanical shaft seal is the most common cause of pump downtime. The shaft seal is exposed to a wide variety of conditions and it can be quite difficult to identify why a seal failed. This post will take a look at the most common costs of seal failure and readdress how we reduce the frequency of seal failure.

Running Dry/Lubrication Failures

The first cause of failure we’d like to highlight in this post is what we call “lubrication failures”. Proper functioning mechanical seals use hard seal materials that depend on lubrication provided by the fluid being pumped. Obviously, if you don’t have any fluid in the pump, that’s not good and your seal will fail. But dry running is not the only time seals can be insufficiently lubricated. At high temperatures or near a fluids vapor pressure, the fluid does not always act as a good lubricant. Lack of lubrication again will lead to friction and heat generation and ultimately seal failure.

The easiest fix for lubrication challenges is to use a mechanical seal with a flush. By using a flush fluid that is compatible with the product, seal life will greatly increase in these challenging applications. Seals are essential for high temperature or vacuum applications.

Contamination/Product Ingress

Another common problem that leads to seal failure is buildup of product on the mechanical seal faces. Sanitary pumps are subject to large swings in temperature, pressure, and velocity. These constantly changing conditions increase the risk of sedimentation in or near the sealing gaps between seal faces. This is a common problem when pumping fluids that tend to solidify quickly and scale on seal faces. As the deposits accumulate on the seal faces, the sealing gap opens further. The result is a leaking seal. This leaking can start slowly at first and increase with time. Accumulation of abrasive particles can also lead to seal face damage, making a bad situation worse. To combat this, exceptionally hard seal faces are recommended for these abrasive applications.

Again, the fix here is to use a mechanical seal with a flush. The flush fluid helps not only to lubricate the seal faces, but also keep them “clean” and prevent product from getting into the seal gap.

Operator Error

There are two primary sources for operator error that results in seal failure. The first is damage during seal removal or cleaning. Carbon, a common material for mechanical seals, is very brittle. Mishandling can easily chip seal faces which quickly leads to a problem. When servicing a pump, care should always be taken to ensure the seals are handled carefully and the seal faces are adequately cleaned.

The second source of operator error is also from improper cleaning. When a pump is taken off line, if it is not properly cleaned, product can solidify on the seals and essentially “lock” the seal faces together. When the pump is brought back online, the high motor starting torque can damage the stuck seals. It is critical to ensure the pump is cleaned properly and product is not left in the product zone. This means CIPing your Universal 2’s and pulling the rotors out and cleaning your Universal 1’s.

Chemical and Physical Degradation

This is the most obvious source of seal failure. If you are pumping an abrasive product, make sure you select compatible seal materials. As a seal wears, the originally smooth seal face becomes worn and pitted, resulting in leaks. And while much emphasis is placed on seal face material selection, it’s also important to ensure that the elastomers used are compatible as well. Swelling and failure of the elastomers can also compromise the seal chamber ,leading to failure. For more information about seal face or elastomer compatibility, refer to our previous posts on the topic.

Vibration

The life span of a mechanical seal is directly affected by shaft movement.  Vibration can cause carbon face chipping and seal face opening.  Seal face opening can result in contaminants to penetrate between the seal faces causing premature wear.  There are a host of causes for excessive vibration including, bent or warped shafts, pump and drive misalignment, worn or loose bearings and unbalanced rotating components.

To conclude, mechanical seal failure is often a combination of a variety of factors. The mechanical seal is a dynamic area of the pump that experiences both temperature and pressure swings. Running dry, operator error, and compatibility issues can all lead to premature seal failure. For help troubleshooting your pumps mechanical seal, contact a Holland Sales engineer today.  

Who is the ASME BPE and What Do They Do?

November 18, 2014
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If you call Holland Applied Technologies to speak with a customer service representative and ask for a 316 stainless steel fitting, you’ll likely be asked “Do you require BPE compliant fittings?”  Previous posts to our blog have spent some time talking about BPE fittings and other parts of the ASME BPE Standards, but it occurred to us that a lot of people don’t know what the ASME BPE is.  This post will go into some more detail.

ASME BPE is an abbreviation for American Society of Mechanical Engineers – BioProcessing Equipment Standards.

The ASME BPE Standards Committee is a collection of the both manufacturers and end users that set out to develop a guideline to  cover the design, materials, construction, inspection, and testing of BioProcessing equipment.

The BPE standards committee is broken down into a series of subcommittees that allow industry experts to collaborate and utilize their expertise to develop a comprehensive approach to all aspects of bioprocessing equipment the subcommittees are:

  • General Requirements
  • Systems Design
  • Dimensions and tolerances for Process Components
  • Material joining
  • Process Contact Surface Finishes
  • Sealing Components
  • Polymeric and Other Nonmetallic Materials
  • Metallic Materials
  • Certification
  • Process instrumentation

As new types of technology come to market, additional subcommittees are developed to address them. Updated standards are published bi-annually. The most recent revision to the standard, published in 2014, covers new topics ranging from hygienic supports to weld discoloration acceptance criteria and dynamic seal performance.

The Standard developed by the ASME for bioprocessing equipment is the leading standard used to design and build equipment for the bioprocessing market. The Standard incorporates current best practices that help equipment manufacturers and end users alike, maximize product purity and safety. By developing a standard, the ASME has allowed companies to improve communication and become more efficient, which results in lower development and manufacturing costs.

To conclude, the question is not so much as to who is the BPE, but what is it. The ASME BPE is a standard developed by ASME members specifically for the bioprocessing market.  Holland Applied Technology personnel actively participate in the BPE meetings.  One of our engineers at Holland is a member of the Systems Design and Certification sub-committees.  If you should ever have questions regarding ASME BPE compliant equipment please contact us at 800-800-8464 or our website www.hollandapt.com

Sanitary Strainers: Perforated or Wedgewire Filter Inserts- Which Should I use?

November 6, 2014
basket-strainer

Sani-Matic Basket Strainer

Since we re-launched this blog, we’ve hit on most of the types of sanitary process equipment we deal with at Holland. One category of equipment we’ve overlooked, however, is sanitary strainers. Today’s post will take a look at sanitary perforated sheet and wedgewire strainers inserts and some of the advantages and disadvantages of each.

To begin, the most common type of sanitary filter insert used in the industry today is a perforated sheet type strainer with a wire mesh overscreen. Perforated inserts will commonly use 14 gauge sheet metal perforated with 60 degree staggered 1/8” or ¼” holes. The 60 degree stagger pattern is preferred because of its superior strength and large open area ratio, increasing filter capacity. Wire mesh linings are often used with the perforated sheets for finer filtration and take advantage of the reinforcement provided by this thick material perforated sheet material. Mesh screens are generally available in both stainless and cloth bag versions. The perforated type of insert is economical.

A common alternative to perforate filter inserts with mesh over screens are wedgewire inserts. Wedgewire inserts have a unique set of advantages that make them ideal for the high purity processing industry. A wedgewire insert is made by welding specially shaped wire to support rods, thereby creating a continuous slot. The wedged shaped profile of the wire allows for fine filtration. With hole sizes as small as 0.005”, filtration as fine as 100 mesh is possible with a wedgewire insert.

The two primary types of wedgewire insert construction are reverse formed and inverted wrap construction. Reversed formed wedgewire inserts feature external support rods which provide a smooth, unobstructed screen surface on the inside of the strainer. The alternative to reverse formed inserts are inverted wrap inserts. Utilizing internal support rods, inverted wrap elements are used as an alternative when the desired basket diameter is too small. The durable, welded construction, allows for a wedgewire insert to outperform and outlast perforated or woven mesh inserts in high pressure applications.

Wedgewire inserts have a few other advantages perforated inserts other than ease of use. The continuous hole spacing means that total percent open area is much higher in a wedgewire insert than with an equivalent woven mesh screen. This increases filter capacity and reduces pressure drop. This higher percentage of open surface area is also going to mean that these inserts are much more cleanable than traditional perforated tubes with mesh inserts. This is huge in a sanitary application where we need to validate or prove that we’re cleaning something.

One other very important advantage wedgewire inserts have over mesh type screens is increased product safety. Mesh screens can fatigue over time.  This can result in individual wire pieces of the stainless steel screen breaking off and migrating downstream into the product.  Using wedgewire inserts eliminates this risk.

Overall, we try to steer our customers towards wedgewire inserts. While they are priced at a premium to perforated inserts, the overall performance of wedgewire decreases total cost of ownership and makes these our “go to” in challenging filtration applications. In processes where we need to minimize pressure drop by maximizing percent open area and assure that we are going to be able to clean the system, the wedgewire is our go to. That’s not to say perforated and wire mesh inserts don’t have their place. For simple applications, such as pump protection, an inline perforated strainer will work just fine. If you have any additional questions about which insert type is right for you, contact a Holland Sales Engineer today.

ITT Pure-Flo Block Body Diaphragm Valves: ZSBT vs ZSBBT- What’s the Difference?

October 28, 2014
The ITT ZSBBS Body

ITT Pure-Flo Zero Static Valve Body with Sampling Port

Even at Holland, where we’re all sanitary process experts, occasionally we can get confused. One issue that came up recently is the difference between ITT Pure-Flo’s ZSBT and ZSBBT valve. We’re going to take this post to review the functionality of a zero static point of use diaphragm  valve and clarify the difference between the ZSBT and ZSBBT zero static valve.

To begin, zero static use points are some of the most critical valves used in the biopharmaceutical industry. A point of use valve allows fluids to be transferred, sampled, drained, or diverted. Zero static valves help us comply with ASME BPE’s L/D dead leg requirements of 2:1. A dead leg is basically a one way water system. Dead legs result in process system that are difficult to clean. Stagnant fluid can also harbor process compromising bacteria.

While the FDA had historically required dead legs not to exceed 6 diameters of unused pipe, the BPE, finding this rule not sufficient to assure sterility, imposed even more stringent requirements. In 1997 the ASME addressed these problems by strongly suggesting (stopping just short of mandating) that the length of a dead leg shall not exceed two times the pipe diameter.

With these stringent requirements, you can see why putting a valve on the branch of a tee could be problematic. As a response to this requirement, the zero static point of use valve has been widely adopted throughout the pharmaceutical process industry. A zero static point of use valve incorporates the outlet valve weir into the main run. Fluid can then be drawn off the main line in a much “cleaner” fashion.

Several variations of the standard zero static diaphragm  valve have also developed, including the zero static sample valve and zero static valve with downstream purge. These block body valves incorporate an integral valve onto the back of the valve assembly that provides access either to fluid upstream of the valve weir (Sample), or access to the process downstream of main valve weir (purge). These integral valve assemblies greatly reduce contact surfaces, hold up volume, and possible dead legs.

So now that we know what a zero static valve does, what is the difference between the ZSBT and ZSBBT valve? The answer is shockingly simple- not much. When ITT originally debuted the ZSBBT valve, they used a faceted body that helped in situations with tight space constraints.

Over time, the market started asking for a more economical zero static valve that could be used in applications without space concerns. To answer this, ITT debuted the ZSBT non-faceted zero static tee. This valve has a squared block body that requires fewer machining steps to make. All other critical dimensions are identical between the ZSBT and ZSBBT valves. All MOC’s and actuation options are the same as well. The only difference are the aesthetics.

So there you have it- the mystery of the ZSBT solved. So the next time you’re looking to replace a legacy ZSBBT valve and you get a quote for a ZSBT, rest assured you are getting a drop in replacement for your legacy valve. For any additional questions about your next sanitary diaphragm valve application, contact a Holland Sales Engineer today.

Which C Series Pump do I have? Finding Replacement Parts for your C Series Pump

October 16, 2014
The C Series Pumps has been a Workhorse in the Sanitary Process Industry for Years

The C Series Pumps has been a Workhorse in the Sanitary Process Industry for Years

Today we’re going to take a look at one of the longest tenured sanitary pumps- the C Series pump. While previous posts on centrifugal pumps have focused on the technical advantages of the Waukesha 200 series and the APV W+ series, this post will take a step back in time and look and one of the legacy pumps of our industry- the C series. Because they’ve been around for so long, this post will take a look at a trick to identify your old C series, as well as a few other ways Holland can help support your aftermarket pump needs.

As a workhorse of many sanitary applications, it’s not uncommon to find a C series pump in service that has taken quite a beating. Often times, casings have been changed, serial numbers have vanished or been misplaced, personnel has changed, and there is little that can be done to identify an old C series pump. Is it a C114? A C216? How can you tell? Well one trick you can use if you don’t have any discernable model information is to measure the backplate. A C114 will have a 4” backplate. A C216 will have a 6” backplate. And can you guess what a C218/328 will have? That’s right, an 8” backplate.

Once you figured out what model you have, identifying spares is easy. You’ll just need to identify the elastomers (how to do that was the subject of a previous post), and figure out your seal materials. Most of the time, a description of the application will be enough to get you into the correct seal parts.

So now that you know what model you have, how do you go about getting parts? Well, regardless of whether you have a Triclover, Ampco, Topline, or Alfa Laval, Holland can supply you with replacement parts. Holland provides genuine Waukesha parts, picked up twice weekly at SPX’s Delevan facility, which are interchangeable with other manufacturers C series pumps. You read that correctly- even if you have an old Tri Clover C114, you can call us up and we will work with you to identify the correct parts.  You can also download C Series parts lists as well as parts lists for all of the other Waukesha pumps we handle on our website.

And while the C series of pump has a simple, elegant design, Holland does offer pump repair for all manufacturers’ C series pump. Our trained technicians work exclusively on sanitary pumps and valves and can turn most repairs around in a couple of days. Best of all, pump evaluation is free. We’ll quickly be able to provide you with actionable information you can use to determine if you want to repair or replace your pump.

So the next time you have trouble identifying or sourcing parts for your C series pump, measure the backplate or call us and we’ll walk you through it. Once we’ve identified the pump, Holland can support all of your aftermarket C series pump needs. If you have any additional questions about any of your sanitary pumps, contact a Holland Sales Engineer today. We’re the one stop shop for all of your sanitary process needs.

Pharmaceutical Filling Needles- Passivation, Ultrasonic Cleaning, and other Cleaning Considerations

October 9, 2014

One area of pharmaceutical processing that we’ve been spending an increasing amount of time at Holland is the world of final product fill and finish. Our last post focused on vial and syringe filling technologies commonplace throughout the industry. Today we’ll be take another look at the fill needle itself and cleaning considerations following manufacture- specifically, ultrasonic passivation.

To begin, ultrasonic cleaning is a process that uses ultrasound and an appropriate cleaning solvent to clean items. Ultrasonic cleaners are fitted with transducers attached to the bottom of the cleaning tank that create vibrations at high frequencies- measured in thousands of cycles (kHz)- and send sound waves through the cleaning solution. The waves create millions of cavitation bubbles that implode on the surface of the material. This cavitation effect lifts contaminants off of the objects being cleaned.

As a corollary to this, passivation, which we’ve touched on before, is used in a wide range of industries to remove free iron by beefing up the passive, chrome oxide layer of stainless steel. Passivation processes in the pharmaceutical industry are generally regulated by the ASTM, specifically ASTM guideline ASTM A 967. The most common type of passivation used throughout the biotech industry is citric acid passivation because it is a low hazard cleaning agent and is biodegradable. Common steps in all passivation procedures include cleaning prior to passivation, submergence in a hot acid bath for approximately 20-30 minutes, followed by a water rinse and drying.

This begs the question- how do you clean both the inside and outside of something as small as a needle cannula? The answer we’ve arrived at is a multistep ultrasonic cleaning process that we feel is most effective in removing free iron and other surface contaminates present in fill needles following manufacture, while protecting the needle design and ensuring superior performance.

As previously mentioned, Holland has been doing citric acid passivation in house for quite some time. We’ve found that applying ultrasonic energy to the process offers two key advantages in the processing of small ID components- speed and thoroughness. The minute bubbles generated by the ultrasonic bath work on all surfaces and are particularly effective at penetrating the small ID’s of fill needles. This allows us to clean both the inside and the outside of the needle in a matter of minutes.

A typical three step ultrasonic needle passivation process starts with the parts being lowered into an ultrasonic citric acid bath. Both temperature and pH of the bath are closely monitored. The cleaning solution and cavitation created by the ultrasonic bath greatly increase the ability to clean both the inside AND the outside of the needle. Once the appropriate temperature and pH have been reached, the parts are placed into the bath for a specified period of time- usually about 20-30 minutes.

At the end of this time period, the parts are removed from the acid bath and placed into a second ultrasonic bath for an ultrasonic water rinse. This step helps remove any contaminants the citric acid pulled out- again on both the ID and OD of the needle.

The final step consists of a final water rinse without any cavitation. Fresh water flows across the parts, removing final contaminants prior to air drying.

So there you have it- a simple, three step process that ensures your filling needle is as clean as all of the other stainless in your facility. At Holland, we’ve been working with passivated stainless steel parts for over 60 years. We’ve been able to leverage that experience to develop robust solutions that assure our customers they receive only the highest quality product because at Holland, we understand that the process is the product. If you have any questions about your next pharmaceutical filling needle application, contact a Holland Sales Engineer today.

Vial and Syringe Filling in the BioTech and Pharmaceutical Industries

September 29, 2014

At Holland, one particular area of the biotechnology industry has becoming increasingly interesting to us is final product fill and finish. We’ve found that many of our core competencies have prepared us to help end users and equipment providers deal with the challenges associated with getting final drug product in a jar. As the pharmaceutical industry continues to evolve, increasing pressure is being been placed on filling machine providers by end users to focus on improving the flexibility, reliability, and efficiency of the filling process. This post will take a look at the most common types of pharmaceutical filling equipment and recent trends that are interesting to us.

Rotary Piston Pumps

While pharmaceutical companies are driving vendors towards single use, disposable dosing systems- systems where the entire fluid path is discarded- the most commonly used filling mechanism used today is still the rotary piston pump. Rotary piston filling machines use a matched set of piston and cylinder to dispense precise volumes of liquid. These machines are suitable for a wide range of viscosities, temperatures, and fill volumes. They work well with a variety of challenging products including shear sensitive or low surface tension products. While this has historically been the most popular type of filling machine, drawbacks include the need to disassemble and clean the machine after each use. CIP/SIP of piston pumps can be problematic and they are not offered with completely disposable flow paths.

Rolling Diaphragm Pumps

This type of filling machine is essentially a variant of a piston pump. These systems use a diaphragm to push and pull product in and out of the machine. While historically also stainless steel, recently technological breakthroughs, such as Dover’s Quattroflow quaternary diaphragm pump, have allowed for the use of polycarbonate pump heads and disposable needles, allowing for a fully consumable flow path.

Peristaltic Pump Systems

While originally used for fluid transfer, rather than high speed, accurate dosing, recent advance in servo-drive controls have given machine suppliers the ability to control the motion and position of the peristaltic pump rollers and have integrated feedback from the machines check weighing system. The key advantage to this technology is that it offers complete disposability, with almost no chance from product cross contamination. Limitations of this technology include limited viscosity range, tubing spallation, and somewhat low precision compared to other technologies.

Time/Pressure

These systems incorporate a pressurized product tank and pinch valves to open and close silicone tubing between the bulk tank and filling needle. In these systems, it is critical to control and monitor tank headspace pressure and overall system conditions. That being said, recent advances in the ability to control the aforementioned has allowed time/pressure systems to become just as accurate as pump systems in some cases. Other big pluses to time/pressure applications are very low shear and compatibility with CIP/SIP.

Drawbacks to time/pressure systems can include inaccuracies due to variation of vessel head space, no disposable flow paths, and an increased amount of time to tune in and start a fill for a process that can be affected by temperature or other factors affecting fluid flow properties.

Mass-Flow

The last type of machine we’ll touch on are mass-flow fill systems. These use mass as opposed to volume dispensing via the Coriolis effected. The Coriolis Effect occurs when fluid passes through a vibrating sensor tube. These tubes, which constitute a Coriolis meter will then communicate with a valve controlling discharge through the machines needles. Mass flow dispensing is the type we see least often, due to viscosity and accuracy limitations, with applications primarily limited to opthamalic product fills.

To conclude, substantial progress has been made toward improving the accuracy and control of the filling process. Increasingly robust technology has enabled rapid changed over and flexible lines that allow users to be responsive to changing customer demands. Holland is proud to offer both stainless and single use solutions, including needles, tanks, pumps, and manifolds (all in both stainless and disposable) to help our customers with their unique filling challenges. For more information about your next fill/finish application, contact a Holland Sales Engineer today.

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