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What are Clean-in-Place Seals?

Cliff • July 17, 2019

Clean in place seals, or CIP seals, were developed to allow a seal to remain in place. This is especially important when the seal gland is partially open, allowing the seal to be flushed of debris.

In a food application , the same chemicals used to clean or flush the system would be used to clean the seal gland. Similarly, when other products such as pharmaceutical or adverse chemicals needed to be flushed, the CIP seal does an excellent job being open to flushing.

CIP Seal Designs and Materials

There are several styles of seals that are often found in these applications. Spring energized seals are frequently used because with this type of seal, the cantilever spring and seal groove can be filled with silicone. The silicone fills the void in the seal cavity and covers the spring, allowing the seal to be flushed.

Another typical design would be a simple lip seal without a spring. The lip can face in either direction. For CIP seals, it’s best to have the open side face the product so that during a cleaning, the complete seal is exposed. This ensures that all debris will be flushed out.

Another advantage to using either Teflon or canned lip seals is that these materials will normally be compatible with any cleaning solutions you use to flush the seal cavity.

CIP Seals and FDA Compliance

When designing for food or drug applications where the seal will be flushed, Eclipse Engineering can design with materials that may be FDA compliant both in the environment and the cleaning fluid used to flush the gland free of debris.

In special cases, double lip seals with lips facing axially in forward and reverse direction can be machined, spring energized, and filled with silicone.

Piston and Plunger CIP Seals

Eclipse also builds and integrates a piston design which has the seal built into the piston. We install a spring in the seal and use silicone to completely occupy the spring groove. This design ensures that no particles can become trapped in the seal groove, as it’s completely integrated into the design.

Piston or plunger designs for filling often take advantage of this integrated design. A typical application could be filling a cup with pudding or some other viscous media.
We often use UHMW, or Ultra High Molecular Weight Polyethylene , for its low-friction, FDA compliance, and ease of cleaning.

There are some cases where the seal is used for one type of product and discarded prior to switching to a different fill. In those cases, ease of removal into stepped glands ensures the seal can be replaced without a gland keeper, which could trap particles and contaminate a batch.

Usually upon any disassembly, a CIP seal is damaged and can no longer be cleaned. This is because the retention devices used are one piece and part of the gland, and are easily flushed with particulate.

The success or failure of a seal design is often dependent on how the seal was installed. There are many seals that easily slip into glands with simple installation procedures. But when installing seals with any volume, it’s important to have an established method to ensure consistent performance of the seal.

Case Study: Angled Spring Grooves for Custom Spring Energized Ball Seats

By Doug Montgomery • February 13, 2025
Learn how Eclipse Seal’s custom spring energized ball seats with angled grooves improve performance

Case Study: Dual Lip Crimped Case Seal in High Speed Rotary Vacuum Application

By Doug Montgomery • January 17, 2025
Eclipse deals regularly with challenging sealing applications from all industries. High pressures and speeds create unique sets of conditions where seal design and material properties are pushed to the limit. While reciprocating applications can certainly test seals to the edge of capability, often times rotary applications can present the greatest challenge to seal integrity and wear life. Unlike reciprocating configurations where the seal is acting on a different part of the shaft or bore throughout it’s operating range, rotary seals must operate on the same sealing area continuously. This makes things like heat rejection much more difficult, especially in unlubricated or dry running applications. Extreme localized heating can have negative affect on both seal and hardware life. Rotary applications also pose sealing difficulties due to the simple fact that surface speeds can be much higher than in reciprocating systems. A simple electric motor can operate at very high rpm, while long stroke, high speed reciprocating machinery is a major piece of equipment that is far less common (though Eclipse also has sealing solutions in a number of these situations). A customer approached Eclipse with an application that was beyond the scope and capability of any standard, off-the-shelf rotary seal. This sealing system would require a combination of both wear resistance in high-speed rotary, as well as excellent leakage control and sealability. Two factors that, more often than not, work in opposition to each other. The Customer Issue The customer was developing a test system that required an electric motor shaft passed through the wall of a large vacuum chamber. The testing apparatus needed a sizable motor to meet the speed and torque requirements. Adapting the motor to operate inside the chamber would not be practical due to contamination and motor cooling concerns. Therefore, the motor would have to be placed outside the chamber and a driveshaft would have to go through the chamber wall. Which, of course, would need a seal. Operating Conditions:
 Rotary Shaft Seal
 Shaft Diameter: 2.5”
 RPM: 7,500 RPM - unlubricated
 Pressure: Vacuum internal side / 1 ATM external side Temperature: 40° - 90°F The customer knew any kind of off-the-shelf rotary seal with a rubber element would not last any amount of time in the combination of speed and a dry running condition. They also knew a single lip PTFE seal would likely not meet their leakage requirements. Therefore, they turned Eclipse for a custom sealing solution.

Case Study: PEEK Spring Energized Seal in a High Temperature/High Radiation Application

By Doug Montgomery • November 25, 2024
Eclipse has engineered sealing solutions for applications all over the planet and in a plethora of environments. From the bottom of the ocean to orbiting the earth, Eclipse is challenged by the unique conditions in each application. Whether it be extreme temperature and pressure or severely caustic or abrasive media, Eclipse has a solution for most every sealing problem. One distinct environment presents a particularly challenging set of circumstances for seal design – high radiation. Eclipse’s primary seal material choice for many applications is PTFE and PTFE blends. With all the wonderful attributes PTFE possesses as a seal material, radiation resistance is not one. In high radiation environments PTFE’s properties can degrade to essentially rule it out as a suitable material. The options for effective sealing materials that are also radiation resistant becomes very limited. The seal designer is therefore confronted with creating a seal that is expected to perform in every way a typical PTFE seal operates, out of materials that are not as favorable to sealing. This is where Eclipse’s engineering experience and expertise in seal design come to the forefront. The Client's Issue Eclipse was approached by a customer that was looking for a seal solution for a sensor used in a nuclear application. It would be operating in an environment with both high temperature and high Gamma radiation. Operating Conditions:
 Reciprocating Rod Seal
 Rod Diameter: Ø1.000
 Stroke: 1.5”
Cycle Rate: 2-4 cycles per minute
 Media: Air, Salt Water Mist
 Pressure: 100 PSI
 Temperature: 70° to 450°F
 Gamma Radiation Exposure: 10^6 rads

Case Study: MicroLip™ – Robust Rotary Sealing in Cutting-Edge Robotics

By Doug Montgomery • November 14, 2024
Technological advancements in the area of robotics have led to more and more life-like creations existing only in works of science fiction a few decades ago. Development in autonomous logic processing and sensing allows bipedal robots to walk over uneven ground, up and down stairs, open doors and carry loads. Fast response to dynamic and unpredictable real-world environments is critical for the future use of robots in true-life service and practical employment in the years to come. While software and sensor development remain the primary focus of most research, the physical mechanics of next-gen robotics are also continually progressing. Physical components and control systems such as hydraulic pumps and cylinders, servo motors, and structural members are under pressure to continually be lighter, stronger, more efficient and less expensive. Increased demands on the physical components facilitate the need for innovative solutions in design and material usage. Advancements in construction and technology have spilled into all areas of robotic mechanisms and the many seals located throughout the system need to meet the challenges of tomorrow. Eclipse has been at the forefront of this research and has developed innovative solutions pushing the boundaries of conventional sealing devices. MicroLip™ by Eclipse is a prime example of most demanding applications forging new technologies in the sealing world. The Client's Issue Eclipse was approached by a leading robotics company looking for a sealing solution operating under a challenging set of conditions. While many components of tomorrow’s robotics are now controlled and actuated by servo/stepper motors and various electronic devices, the heaviest and most powerful movements are still driven by traditional hydraulics. The constant demand for more powerful hydraulic actuation in ever deceasing size and weight requirements has put tremendous strain on component design. But if robots are to progress to the point where they are usefully employed in the world, high power in a compact design is necessary. A robot, for example, used to survey and assist in a disaster zone too unstable for normal rescuers, must fit through doorways and over obstacles yet still be physically strong enough to render assistance. Large hydraulic systems are capable of moving extremely heavy loads but size and weight constraints of a humanoid size robot limit potential. The robot’s internal power supply to drive all components is also a limiting factor. Our client was developing a new hydraulic pump to drive all major motion aspects of their robotic systems. Their main objective was to minimize the pump’s physical size as much as possible while increasing output and improving power consumption efficiency. This means higher pressures and speeds on increasingly smaller and lighter components. Application Parameters: Shaft Diameter: Ø9.5mm Seal Housing Envelope: 5mm radial cross-section by 6mm axial width Rotational Speed: 3,500 RPM nominally; 6,000 RPM max Operating Pressure: 125 PSI min, 225 PSI nominal, 350 PSI max Surface Finish: 0.04µm Media: Hydraulic Oil While the above combination of pressure and speed might present difficulties for any conventional seal alone, the client’s extremely small physical envelope to house the seal further complicated the matter. If that wasn’t enough, the application presented the additional sealing challenge of up to 0.003” [0.08mm] of shaft runout. As part of the downsizing of all components in the pump, shaft support bearings were minimized leading to the possibility of runout. The wobbling effect of the shaft creates problems as the sealing lip has follow a moving, uneven mating surface, therefore potential leak-paths are created. Wear life can also be compromised due to higher concentrations of uneven loads. The combination of high pressure, high speed, high runout and minimal gland size present a worst-case scenario for a typical seal. Unsurprisingly, the client faced leakage of hydraulic fluid after only short periods of service with any conventional seal they had tested. Eclipse knew the had the perfect solution for this application. One developed to handle such extreme rotary sealing conditions: MicroLip™.
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