Monthly Archives: May 2020
- May 29, 2020
Fluid power seals used in pneumatic cylinder systems represent some of the most overlooked, yet vital components in its construction and operation. Without these rubber seals – or if using inferior seals – the friction and leakage created by the process of using a pneumatic cylinder application could cause the equipment to catastrophically fail, risking severe damage and injury, and requiring great cost to repair or replace.
Gallagher Fluid Seals' partner, Precision Associates, has innovated to create our own unique and patented compounds for rubber pneumatic piston seals—suitable for all sorts of pneumatic applications. These U-Cups are designed to function with vastly lower breakaway and operating friction than any similar product in the marketplace.
What Are Pneumatic Cylinder Systems?
Utilizing compressed gas as a power source, mechanical pneumatic cylinders produce a reciprocating linear motion force. Like hydraulic cylinders, this force drives a piston in the required direction and the piston is usually a disc or cylinder. The corresponding rod transfers the force it creates to the object requiring movement. Engineers often choose pneumatic cylinders over other methods due to pneumatics being quieter, producing less waste, and requiring significantly less amounts of space for fluid storage.
Pneumatic cylinders can vary in configuration, but generally fit into one of three specific categories:
- May 26, 2020
When designing for low temperature sealing, the first step is to define the temperature range that the seal will be operating in.
Typically, cryogenic as seals are those that are operating below -65 Fahrenheit. Gallagher's partner, Eclipse, chooses this benchmark because they currently have elastomers that have a usable TR10 value at this temperature.
When designing at this level — with high temperatures around 300 Fahrenheit — an understanding of what level of leakage control is required on the low temp end. Seals that operate in aircrafts must function within this range.
However, there may be an allowable leakage rate which allows for reduced drag. When requiring zero leak, the drag in the system is often increased to support some elastomeric contact with a dynamic surface. In the case of static seals, elastomers span this range although increased squeeze may be necessary.
Eclipse Engineering routinely designs in the range indicated above.
While -65 Fahrenheit is extreme cold, it's not considered cryogenic. Liquid nitrogen at -320° Fahrenheit (-195°Celsius) requires special hardware and seal material consideration.
To begin, many projects and applications don't utilize lubricant in dynamic applications. To improve sealability, a better-than-average surface finish is required.
Surface finish often holds lubricity. But without this, a smooth finish reduces friction, improves life, lowers drag, and improves sealability.
Static seals are often required to have leak rates approaching zero; meaning hardware considerations and surface can be even more important. This may mean polishing the groove, which in some applications can be very challenging.
Cryogenic Seal Materials
The next criteria are the seal materials. Elastomeric materials lose their flexibility at these extreme temperatures, so Eclipse relies on polymer-type materials to bridge the gap. When we experience temperatures below -180° Fahrenheit ( -195° Celsius), that's when it becomes wise to move away from basic PTFE to modified fluoropolymers such as PCTFE, known for operating down to -460 Fahrenheit.
- May 21, 2020
Metal Detectable O-Rings are a Must-Have in the Food & Beverage Industry
Metal Detectable O-Rings are used in equipment that produce and package food. During service, o-rings are exposed to temperature variations and corrosive clean-in-place (CIP) chemicals used during equipment sterilization.
Over time, o-ring materials can break down and fail during operation causing material fragments from the o-ring to break off and enter the food stream. Without a way to find material fragments quickly, machine operators must shut down equipment to locate the contaminate source resulting in lost production time and loss of revenue.
Metal detectable o-rings from DICHTOMATIK are formulated with the specific rubber and metal combination that allows for easy detection using
- May 19, 2020
Attention: When installing GORE Gasket Tape Series 1000 in joints with multiple (2 or more) gaskets compressed with a single set of bolts or clamps, see the installation supplement “Installation on Joints with Multiple Gaskets,” for additional mandatory instructions.
1. Select the size
GASKET WIDTH
Select the gasket width that provides enough material to align the gasket tape flush with the inner and outer diameter. Ensure full coverage of the glass surface. Excess material may exceed the outer diameter.
GASKET THICKNESS
Most applications require a base layer of 6 mm (1/4") tape, which can accommodate deviation up to 1.5 mm (1/16") without shimming. Applications with deviation up to 2.3 mm (0.090") can utilize 9 mm (3/8") tape without shimming.
SHIMMING
To effectively seal flanges with deviations beyond the maximum for the base layer, a shimming process is recommended. Use of 3 mm (1/8") GORE® Series 1000 shim tape as a shim layer will accommodate an additional 1.5 mm ( 1/16") of flange deviation. Ensure the shim layer has the same width as the base layer.
2. Determine a Torque Value
To achieve a reliable seal, adequate gasket stress must be applied during installation.
Typical minimum stress to seal values for GORE Gasket Tape Series 1000 are:
- 6 mm (1/4"): 14 MPa (2,030 psi)
- 9 mm (3/8"): 18 MPa (2,610 psi)
Perform an engineering calculation to determine the torque value for your specific application.
Industry guidance is available, for example in ASME PCC-1 Guidelines for Pressure Boundary Bolted Flange Joint Assembly, and EN 1591-1 Flanges and their Joints - Design Rules for Gasketed Circular Flange Connections - Part 1: Calculation.
However, ASME PCC-1 does not include glass-lined steel specialties. Therefore, it is advised to contact the equipment manufacturer for an adequate torque recommendation.
- May 15, 2020
Article re-posted with permission from Parker Hannifin Sealing & Shielding Team.
Original content can be found on Parker’s website and was written by Dan Ewing, senior chemical engineer, Parker Hannifin O-Ring & Engineered Seals Division.
In the rush to massively increase the number of medical ventilators available to treat patients with severe cases of Covid-19, using the correct seal materials for those ventilators should never take a back seat to expediency.
Medical ventilators are mechanical devices that essentially breathe for a patient with damaged lungs. They force air into the lungs and draw it out, augmenting or even replacing the natural functions provided by the movement of the diaphragm and the inflation/deflation of the lungs themselves. These devices can supply room air, pure oxygen, or nearly any ratio of the two to the patient, depending on health needs.
What makes a good seal selection in this environment?
First, seals within the device must be compatible with air and pure oxygen. They should not harden or crack, nor should they contain a significant amount of volatile matter that can evaporate out of the seal where it could be inhaled by the patient or potentially catch fire in a concentrated oxygen environment. Further, it should be assumed that any air that contacts the seals will likely end up in the patient’s lungs. As a result, it's strongly recommended using seal materials that have passed USP <87> Class VI testing for any seals used in a medical ventilator.
Parker O-Ring & Engineered Seals Division has already helped several customers ramp up production of critical medical equipment with supplying the right materials and O-rings for the application.
These application requirements limit the recommended compounds to only a small handful.
Recommended compounds suitable for use in ventilators
- May 12, 2020
It’s no news that coal-fired generation is going by the way-side. Despite a recent resurgence in political support, coal is fighting an uphill battle on two major fronts: economically and environmentally. After the shale gas boom in the 2000’s, plummeting natural gas prices and rising environmental concerns have continued to make operating aging coal-fired plants less and less attractive – for owners and consumers alike. The recent slowdown issues with the pandemic are only exacerbating the conditions – as industrial and commercial sectors are the greatest consumers of electricity. With only the cleanest and most efficient plants left in operation (in 2010 coal generated 45% of the nation’s electricity, compared to 24% by the end of 2019) and the rest quickly moving towards eventual closure, we are witnessing a tremendous shift take place. So how is this shift going to resolve and what should we expect?
Long-Term Changes
Fortunately for us in 2020 – the shift away from coal has been happening long enough that new generation capacity has already been under construction and is coming online just in time to replace the retiring coal plants. The economic downturn effecting industry has showed an acceleration in these trends – but natural gas and renewable outputs have been rising to pick up the slack for over a decade. In fact, the U.S. has been somewhat lagging behind in terms of progress towards renewables with some European countries already shutting down the last of their coal-fired plants. Though domestic renewables are indeed growing significantly – having nearly doubled in power production in the past ten years, and are expected to double-over again and overtake natural gas by 2050.
- May 08, 2020
High Performance Seals for Polycrystalline Silicon Process Equipment
The Challenge
To meet growing demand in solar cells, the Siemens* process is used to produce highly purified polycrystalline silicon by thermally decomposing tri-chloro-silane (TCS). The reactors employed require three kinds of high-performance seals in the following locations: A) bell jar seals; B) electrode seals between the electrode and ceramic inlet; and C) a gasket for the view port seal (see schematic).
Application Details
The process involves a very hot, dry environment with temperatures up to 1200°C (2100°F). Sealing components see up to 300°C (572°F). Process media include TCS and aggressive by-products of its decomposition, such as HCl gas. Superior compression set performance is needed for effective sealing and extended seal life. Very low outgassing is a key requirement for preventing contamination of the process environment.
The presence of harsh chemicals in high temperature conditions often require an upgrade from standard sealing materials to PTFE or fluoroelastomers (FKM) to improve thermal stability and chemical resistance. However, PTFE can deform and creep “hot flow” in the bell jar seal increasing the risk of product loss. FKM, with its high temperature rating of 200°C (392°F), also has deficiencies in this 300°C (572°F) environment.
The Solution and Key Advantages of Kalrez PV8070
Kalrez PV8070 perfluoroelastomer parts installed as washers and gaskets in reactors for the Siemens CVD process have demonstrated outstanding performance in this demanding application. Kalrez® PV8070 parts are effective seals that provide:
- May 06, 2020
In addition to KLINGER's complete Sheet Gasketing Product Line which now includes the new major change in construction of their PTFE Products TC 1003, TC 1005, and TC1006, they have added a great new product to cover additional applications during day-to-day operation.
The KLINGER SAVER
A new product we are featuring on our blog is THE KLINGER-SAVER - a tool to eliminate hand injuries.Bolt tightening or loosening activities, or using slug wrenches and hammers can often the cause of serious finger or hand injuries.
The KLINGER-SAVER is a safety device that allows an assembly technician to remove his hand from the potential danger of being struck by the hammer.
How The KLINGER-SAVER Works
The wrench - May 04, 2020
EPR vs EPDM - How do they differ?
What’s the difference between EPR and EPDM? What do the different abbreviations (EPR, EPM, EPDM, EPT, etc.) mean? These questions pop up from time to time in the seal industry, and here are basic answers to these questions.
In the range of ethylene-propylene (EP) rubber there are two lightly different branches: EPR (EP copolymer) and EPDM (EP terpolymer.) The differences are subtle, and a basic knowledge of polymers and rubber compounding is necessary to grasp the differences.
First of all, polymers (derived from the Greek for “many units”) are long chemical chains that can be thought of as behaving like long pieces of cooked spaghetti. Each chain is made of one or more monomers (Greek “single unit”) linked together end-to-end.