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Proper Elastomeric Seal Selection for Process Analyzer Sample Systems. Steve Doe Parker Hannifin Corporation. Topics Elastomeric Seals & NeSSI Compounding O-Ring Design Chemical Compatibility. Proper Elastomeric Seal Selection for Process Analyzer Sample Systems. Elastomeric Seals & NeSSI.
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Proper Elastomeric Seal Selection for Process Analyzer Sample Systems Steve Doe Parker Hannifin Corporation
Topics • Elastomeric Seals & NeSSI • Compounding • O-Ring Design • Chemical Compatibility Proper Elastomeric Seal Selection for Process Analyzer Sample Systems
Elastomeric Seals & NeSSI No Matter Which System...
Elastomeric Seals & NeSSI …Elastomeric Seals Are In The Picture!
IntraFlow Pressure Connector R-Max Surface Mount Interface (not SP76) SP76 Interface Don’t: Expose Seal ID to Fluid Flow Do: “Capture” • Elastomeric Seals & NeSSI Seal Do’s & Don’ts
Metal and plastic retained elastomeric composite seals • Polymeric and plastic seals • Homogeneous and inserted elastomeric shapes • Elastomeric O-Rings • Rubber and plastic boots/bellows • Extruded and precision-cut and fabricated elastomeric seals • Thermoplastic engineered seals • EMI shielding and thermal management products • Seal Group Products
Mold Onto Stainless Wafer • Elastomeric Seals & NeSSI • Alternatives: • Special Geometry O-Ring Seal • Stick With 2-007 in Couterbore (what we have)
“… designs and manufactures engineered elastomeric o-ring seals.” • Parker O-Ring Division
Failure Modes Extrusion & Nibbling Spiral Failure Cutting Explosive Decompression
The seal swells, shrinks, loses physical properties, or gets brittle. • Excessive swell, brittleness, and dramatic loss in physical properties • Shrinkage: the fluid is extracting something from the rubber (changing the base polymer usually isn’t required.) • Failure Modes Chemical Attack
Butyl (IIR) Neoprene (CR) Ethylene-Propylene (EPR, EPDM) Fluorosilicone (FVMQ) Nitrile (NBR) Polyacrylate (ACM) Hydrogenated Nitrile (HNBR) Polyurethane (AU, EU) Silicone (VMQ) Fluorocarbon (FKM) Tetrafluoroethylene-Propylene (TFE/P) Perfluoroelastomer (FFKM) • O-Ring Polymers
GLT V0835-75 A V1164-75 B V0834-75 Extreme V1260-75 GFLT V1163-75 GF V0965-80 Hifluor V3819-75 NEW V1263-75 ParofluorTM V8545-75 • Performance of Fluorocarbon
Parofluor™ Ultra Parofluor is a true Perfluoroelastomer polymer The Parofluor base polymer is a composition of 3 or more monomers A & B represent different fillers and curatives used to enhance physical & thermal properties
Physical Properties FF500-75 FF200-75 Chemraz 505 Kalrez 4079 Kalrez 1050 Kalrez 6375 Durometer, Shore A 75 75 75 75 80 75 Tensile Strength, psi 2045 1740 1750 2450 2700 2200 Modulus at 100%, psi 1262 1131 1150 1050 1800 1050 Elongation, % 135 124 140 150 125 160 TR – 10, F +6 +5 +5 - - - Temperature Range, F 5 to 525 5 to 608 5 to 446 to 600 to 550 to 527 30 Compression Set, 70 hrs at 400F, % (2-214 O-rings) 19 16 25 25 35 • Parofluor™ Ultra
Base polymer determines chemical resistance, rough temperature limits, and rebound resilience • In some materials, the high and low temp limits can be modified by other compounding ingredients. • Provides “baseline” for abrasion resistance, compression set resistance, permeability • These can (and almost always are) modified – up or down – by other compounding ingredients. • Compounding: Polymer Selection
Polymer chains must be cross-linked to achieve resilience and elasticity. • Sulfur • Organic Peroxides • Bisphenol • Others: specialty materials have special cure chemistry • Compounding: Cure Systems
Reinforcing agents add mechanical strength and resistance to abrasion & permeation • Carbon black: standard for black compounds • Silica: standard for non-black compounds • Fillers lower the cost of a compound but reduce compression set resistance and elongation • Compounding: Fillers
Oils and / or polymers to lower the low temp limits and make the material flow better • Reduce resistance to compression set • In “generic” materials, they are used to offset the hardening influence of high levels of filler • Can extract into process fluids, resulting in seal shrinkage & hardening • Compounding: Plasticizers
Compression Set HD HF HI HI = Original Height HD = Compressed Height HF = Recovered Height Compression Set records the amount of permanent deformation of a compressed sample over time. The Lower the Number, the Better Sealing Ability.
Compressive Set Relaxation FS FS = “Spring Force” Compressive Stress Relaxation records drop in “Spring Force” over time generated by a compressed rubber sample. The Higher the Number, the Better Sealing Ability.
O-Ring Design Is Easy! It’s the O-Ring groove that needs special attention
What makes a reliable O-ring design? • Squeeze • Seal deforms significantly (~25%) • Rubber does not compress or lose volume • Stretch • Gland fill • Volume-to-void ratio • Surface finish • Balance of machining costs with application & testing needs • Installation • Protect seal from sharp edges • Provide lead-in chamfers • O-Ring Design
Compression expressed as a percentage of the free-state cross-sectional thickness of the O-ring. • (O-Ring C/S) - Gland Depth • (O-Ring C/S) • Face Seal: 20-30% • Static Male/Female: 18-25% • Reciprocating: 10-20% • Rotary: 0-10% • O-Ring Squeeze
O-Ring volume as a percentage of Gland volume. • (O-Ring Volume) • (Gland Volume) • About 25% void space or 75% nominal fill • Need space in groove to allow for volume swell, thermal expansion, and increasing width due to squeeze • O-Ring Gland Fill
Website Resources www.parkerorings.com www.parofluor.com
Acknowledgements Dan Ewing, Seal Application Engineering Manager Natalie Hicks, Seal Application Engineering Manager
Parker IntraFlow™ Patent Pending Thank You!