Category Archives: sealing technology

What is the ZAVA® Seal-Ring

Here Comes the ZAVA® Seal-Ring

“At last” – that’s the reaction of those who have been plagued by the constant need to change rubber seals on VFA and CCA filters at pulp plants all over the world. As an electrician at SCA Pulp in Sundsvall, Frans Sramek is the man that has solved this well-known, and seemingly hopeless problem. The ZAVA seal can be mounted in minute and cuts maintenance costs substantially.

“It’s always a pleasure to be able to offer our customers products on which they make money,” says Lars Bylund, Customer Service Division at Sunds Defibrator.

Four hours work in one minute

One of ZAVA® Seal-Ring’s prominent features is ease of installation. The rubber ring is locked in place using a quick-connect coupling, which is impossible to separate once it has been assembled. The designer is reluctant to say more. Patent protection is important.

As far as maintenance is concerned, vulcanizing is just a memory. The seal-ring is changed easily in less than a minute, without shutting down the filter. It’s an undertaking that would otherwise take three to four hours. The time saved is a strong argument for the ZAVA seal-ring, but not the strongest.

picture of zava seal-ring

The rubber composition withstands anything

No one would go out on a limb and claim that any material, exposed to all the chemicals present in a pulp plant, is maintenance-free. But the ZAVA® Seal-Ring is at least giving the maintenance people at Östrand cause to wonder.

For almost six months, the ZAVA® Seal-Ring has been tested on the plant’s filters without  sign of loosening or brittleness which are otherwise normal phenomena. The same thing is being experienced at MoDo in Husum.

“The rubber composition seems impervious to both acid and alkali environments of normal concentration,” says Sven-Erik Sundin, spare parts sales engineer at Sunds Defibrator, who has witnessed several less successful approaches to the problem.

Frans Sramek developed the rubber composition with the help of a good friend in the tire industry. If anything, the formula is an even bigger secret than the construction of the mounting device.

An end to mess and waste

An improved work environment is one of the main reasons why the ZAVA® Seal-Ring has won the approval of mill maintenance and operating personnel.

Previously, replacement of a leaking seal-ring was postponed until a normal production stop or periodic maintenance. As a result, it became increasingly difficult to keep machine areas clean as leakage increased.

So far, the ZAVA® Seal-Ring has proved to be completely tight. This also means that losses of black liquor and other chemicals have been minimized.

ZAVA® Seal-Ring creates new filter designs

Sunds Defibrator’s design people have become infatuated with the ZAVA® Seal-Ring. One idea being tested is to eliminate the inner seal-ring (V seal-ring) on VFA and CCA filters. This will result in a further reduction of maintenance since the seal cover would not have to be separated.

It can become a reality if the ZAVA® Seal-Ring proves that it can withstand the stresses. Åke Sundström, head of filter design at Sunds Defibrator says: ”We believe that, at last, we can avoid the troublesome V seal-rings on the covers. With a few minor design changes, an externally mounted ZAVA seal-ring should handle the entire job.”

Industry Application

ZAVA® Seal-Rings are available for many industries and in a number of materials and profiles. Industries like:

  • Chemical Processing
  • Energy, Oil & Gas
  • Heavy Equipment
  • Maritime Sealing
  • Pulp & Paper
  • Hydro Electric
  • …and more

Check out their video below:

For more information about the Zava Seal-Ring, contact Gallagher Fluid Seals or find more information on ZAVA’s website.

Gallagher Case Study: Design and Fabrication of Custom Molded Gasket

Gallagher Fluid Seals helps meters & instruments manufacturer through the design and fabrication of a custom-molded gasket with an engineered profile.


The Problempicture of micro corrector

Our client’s micro corrector was experiencing water intrusion past the gasket, caused by improper seal material and configuration.

The Approach

Gallagher Applications Engineer Benjamin Mell worked closely with our client to identify & address the issue and suggested sending a sample of the instrument to GFS headquarters. Our engineering team received the hardware and investigated the root cause of the seal failure.

GFS engineers observed that our client’s closed-cell foam gasket had taken a severe compression set. This was limiting the life & effectiveness of the foam seal, which in turn allowed water to penetrate the instrument and damage the electronics.

The Solution

picture of the red seal inside the micro corrector
Figure 1.

Based on our experience and industry insights, GFS was contracted to design & fabricate a custom-molded gasket with an engineered profile to properly mate with the hardware and perform to customer expectations/ requirements. (see Figure 1. red seal)

Results / Next Steps

The Gallagher-engineered gasket solution was a success; it eliminated water intrusion and damage to the electronics, reduced warranty claims, and provided a more reliable product.

With the success of this project, GFS is partnering with our client for additional custom solutions. Next, we plan to help design and fabricate a window seal on the micro corrector to further decrease the possibility of water intrusion.

For more background about this case study, click here.

The Perfect Wave; The Gerromatic Rotary Seal

Gear motors, pumps and stirring units keep process material in constant motion in the process industry’s production facilities. A large number of shaft seals are used at drive shafts to keep liquids securely within the equipment. But leaks may be more likely to occur if the pressure acting on the seals becomes too great. Freudenberg Sealing Technologies has developed a new rotary seal, the Gerromatic, which has a wave-shaped sealing lip. This increases the maximum amount of pressure that can be applied. The sinusoidal contact path also reduces friction and provides self-cleaning, which extends operating life.

In the process industry, including the food and beverage sector, shaft seals used in equipment mostly have a rotation-symmetrical seal lip, which abuts the rotating shaft with a groove-like contact pattern. During wet-running, this can cause the medium to be displaced at the contact surface. The seal then runs in a more or less dry condition, leading to increased friction and higher temperatures. The increased friction increases wear and reduces the efficiency of the equipment. The accompanying rise in temperature is not desirable, especially when the process media are temperature-sensitive. If the seal lip is also exposed to high temperatures at high rotational speeds – for example, due to a process material that applies pressure to the seal lip in a vessel with a stirring unit below it – the lip can fold down on the low-pressure side, which would result in immediate leakage and the seal’s failure.

Continue reading The Perfect Wave; The Gerromatic Rotary Seal

Chemical Compatibility: A Critical Component in Seal Design

Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.  Original content can be found on Parker’s Blog.

Chemical CompatibilityA common question fielded by Parker O-ring Application Engineers is “will a (insert polymer family) O-ring work with (insert chemical mixture).” Not a day goes by where I do not field this question in some way, shape, or form. Which, honestly, makes perfect sense, because chemical compatibility is one of the two most important factors in designing a seal, the other being size. Choosing the right compound can literally make or break your seal and to the general designer, this can be a massive undertaking. There are so many rubber compound families out there and hundreds and hundreds of chemicals, so how can you know whether your seal is going to hold up? Well, today, I hope to give you a simple, and quantitative way to figure that out.

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Parker Resilon® 4350 Polyurethane

The Engineered Polymer Systems Division of Parker Hannifin Corporation, the global leader in motion and control technologies, has launched a new material, Resilon® 4350 Polyurethane, delivering unmatched high temperature seal performance and reliability for a wide range of applications. This new material extends the high temperature sealing range of polyurethanes by over 20°F.

Resilon Polyurethane - Hydraulic Sealing Systems

Parker’s Resilon Polyurethane is the established industry leader in high performance hydraulic sealing systems.  This newest addition, Resilon 4350, increases the high temperature operating window from 230°F to 250°F for continuous use in many applications while other critical performance attributes such as wear resistance, extrusion resistance, glass transition temperature, and rebound remain best in class.   All of this adds up to a new solution for seal designers as they push the envelope in temperature extremes.

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3 Advantages of a Double Chamfer Radial Seal

double chamfer radial seal

Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.  Original content can be found on Parker’s Blog.


O-Rings are still considered the “go-to” sealing element in many applications.  They can seal a wide range of pressures, temperatures, and tolerances.  They also require very little room, are readily available, and easily sourced.  But there are applications that may be better suited with an alternate type of seal, such as a double chamfer radial seal.

In a recent blog post, our partners at Parker discussed the advantages of using a double chamfer radial seal.

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Fluid Power Sealing Theory

Fluid Power Sealing TheoryThere are a multitude of options when it comes to selecting the most suitable sealing product for your application.  And for those who are not familiar with sealing technology, the number of options can be really confusing.  Gallagher can help.

We pride ourselves on being “The Seal Specialist”, and our engineering department is ready to help seal your toughest application.  But where do you even start?  Keep reading to learn more about some of the fundamentals of seal design and fluid power sealing theory from our partners at Parker.

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VIDEO: Gore GFO Fiber vs Graphite/PTFE Packing

When tested alongside generic graphite/PTFE packing, packing made of 100% Gore® GFO® Fiber achieves better results for all key attributes: creep resistance, retention of lubricant, sealability, and stability (shrinkage).

The differences in performances for each generic packings will have an impact on the operational costs.

Based on calculations for a 100 psi (6.9 bar) pump, 2 inch saft (50 mm); Drip rate 25,000 gallons (94.6 m3)/ year; Packing = $40; Replacement of packing = 3 times per year; kWh = $0.12







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Download Fluid Power Sealing Case Study

fluid power sealingSeals are the most crucial element of a fluid power system, and the engineers at Gallagher have spent more than 60 years cultivating their fluid power sealing skills.

Fluid power seals need to be able to survive higher pressures and more extreme conditions, while having to seal against evolving fluids.

Continue reading Download Fluid Power Sealing Case Study

100% ePTFE Gore GR Sheet Gasketing

gr_iuo_bended-300x200There are so many options when it comes to gasketing material for your process or product that choosing the right one can be overwhelming.

Fortunately, Gallagher’s six decades in the sealing business has allowed us to become experts in specifying the correct material for every application.

One of the more versatile materials in our arsenal, for both standard and custom-shaped gaskets, is GORE® GR Sheet Gasketing.

Continue reading 100% ePTFE Gore GR Sheet Gasketing