o-rings catalog print.pdf · 2019-03-08 · in seal and gland design, the axial direction is...

O-RINGS

713.692.7114 • Fax 713.692.07351120 McDaniel • Houston, Texas 77022888.692.7114 • www.gulfrubberco.com

888.692.7114www.gulfrubberco.comPg 2

713.692.7114 • Fax 713.692.07351120 McDaniel • Houston, Texas 77022 Pg 3

O-RINGS & O-RING MATERIALS


O-RING MATERIAL DESCRIPTIONS

NBR (NITRILE, BUNA) HNBR, HSN -40 F to 250 F -40 F to 320 F

Presently the seal industry’s most widely used A nitrile compound with excellent elastomer. Nitrile combines excellent resistance resistance to petroleum oils and sour to petroleum-based oils and fuels, silicone gas. HSN has excellent wear, low grease, hydraulic fluids, water and alcohol. compression set and good chemical It has a good balance of working properties resistance while maintaining a good such as low compression set, high tensile temperature range. HSN is becoming a strength, and high abrasion resistance, more preferred compound in the combined with a low cost. oilfield industry. TFEP (Aflas) FKM (Viton) -20 F to 400 F -15 F to 400 F Aflas is a unique fluoroelastomer, a copolymer Featuring excellent resistance to petroleum of tetrafluoroethylene and propylene. It has products and solvents, with good high shown excellent resistance to petroleum oils, temperature and low compression set steam, hydrogen sulfide and amine characteristics. For use with wide chemical corrosion inhibitors, It has show excellent exposure situations, and low gas permeability. heat and chemical resistance. Due to its resistance The family of Viton materials and uses are to sour gas and steam it has found numerous as follows: applications in the oilfield industry for chemical injection pumps, downhole A – general service Viton used for many oilfield packer elements and numerous chemical applications. other sealing applications. B - shows improved resistance in aqueous inorganic acids. F/GF – for use in hot water, steam and has improved acid resistance (vs B) ETP-Extreme – strong bases, polar solvents most chemical resistant. GLT – exhibits best low temperature capability. GFLT – exhibits low temperature and chemical



O-RINGS & O-RING MATERIALSGlossary

AA | Axial envelope

This glossary does not give all the definitions for a word, only those which apply to the use of the word as found in this manual. The reader should also refer to a standard English dictionary or consult factory for definitions of trademarks or special terms.

AA. Arithmetic Average. A term for surface finish measurement. It is the same as Ra and CLA, and is calculated by measuring the average deviation of surface irregularities from a mean line.

abrasion resistance. The property of a material which resists the cutting action of sharp edges or hard particles.

abrasive. 1. a substance which abrades the seal, such as sand or dirt. 2. Exerting a cutting action on the seal, such as sand or dirt. 2. Exerting a cutting action on the seal (e.g. a rough mating surface can be abrasive to the seal).

acrylonitrile-butadiene copolymers. Abbr. NBR. A family of copolymers ranging from about 18 to 50 % of acrylonitrile and sometimes including small amounts of a third monomer. The family includes the German materials Perbunan and Buna-N and the nitrile rubbers. These materials are known for excellent resistance to oils, fats and hydrocarbons such as motor fuels, making them useful for gaskets, abrasion linings, conveyor belts, and hoses for handling oils and fuels.

“A” diameter. The smaller of the two mating-surface diameters, that make up the seal gland. For example, the rod diameter when designing a rod seal, or the piston-groove diameter when designing a piston seal.

aging. 1. The process of, or the results of, exposure of plastics to natural or artificial environmental conditions for a prolonged period of time. 2. Refers to a degradation of material properties resulting from exposure to heat (heat aging) or chemicals.

aliphatic. The class of organic compounds such as petroleum and propane whose molecules have their carbon atoms linked in open chains and not arranged in a ring structure. Compare aromatic.

ambient temperature. The surrounding temperature of the environment, assumed to be 70ºF unless otherwise stated.

anneal. To subject a material (such as glass, plastic, etc.) to a process of heating and slow cooling in order to increase toughness, reduce brittleness, or improve dimensional stability.

anti-extrusion ring. A support ring, usually made from a harder material, placed behind the seal to prevent extrusion into a gap. Also see backup ring. .anti-rotation device. Any of various methods used to hold the OD of a rotary-seal design static in its housing to prevent it from rotating with the shaft. .

aqueous. Pertaining to, similar to, containing, or dissolved in water; watery. Refers to media that are water-based, or aqueous solutions.

aromatic. Of, pertaining to, or containing the six-carbon ring characteristic of the benzene series or related organic groups. Also see aromatic hydrocarbon.

aromatic hydrocarbon. A hydrocarbon with a molecular structure involving one or more rings of six carbon atoms, and having properties similar to benzene, which is the simplest of the aromatic hydrocarbons. Other members of this family include many solvents for plastics.

autoclave. 1. A strong, pressurized, steam-heated vessel, used to establish special conditions for chemical reactions, for sterilization, and for cooking. 2. To subject a food-handling or medical instrument to sterilization in an autoclave to disinfect or sterilize the component.

axial. Located on, around, or in the direction of an axis. In seal and gland design, the axial direction is parallel to the center line of the seal and its housing. Compare radial.

axial envelope. The total amount of axial space available to the seal designer for a system of one or more sealing components.


Glossary

AA | Axial envelope


















Glossary

AA | Axial envelope


















GLOSSARY


Backup | CFC

backup, or backup ring. A ring, usually made of a harder material, placed behind the seal to support it under high-pressure or temperature conditions. Also see anti-extrusion ring.

bar. A unit of measure of pressure equal to 105 newtons per square meter of 0.987 standard atmospheres.

“B” diameter. The larger of the two mating-surface diameters that make up the seal gland. The housing diameter when designing a rod seal, or the bore diameter when designing a piston seal.

bend point. That point in a lip design where the sealing surface, changing the lip orientation by 90º

benzene. A clear, colorless, flammable liquid C6H6 derived from petroleum and used in, or to manufacture a wide variety of chemical products including detergents, insecticides, and motor fuels. Also called “benzol”. Also see hydrocarbon.

bidirectional. Operating in two directions at once, such s bidirectional pressure. A seal which is bidirectional can seal two different media, or media acting from two opposing directions, especially when the pressure differential switches from one side of the seal to the other.

blend. 1. To combine or mix so as to render the constituent parts indistinguishable from one another. 2. That which is blended, a mixture. Blend typically refers to a seal material made with a base resin such as PTFE compounded with fillers such as carbon or graphite.

blended radius. A rounded corner, such as on the edge of a shaft, which has been smoothed to provide an easier surface for installing the shaft into the seal.

bore. A hole or passage made as if by drilling. The interior diameter of a hole, tube, cylinder or the like. In a piston-seal gland, the OD of the seal runs against the bore.

breakout friction. The initial frictional force between two unmoving surfaces which must be overcome to get one surface into motion against the other.

Buna-N. See acrylonitrile-butadiene copolymers.

burnish. To polish, smooth, or make glossy as if by rubbing.

burr. A rough edge or area remaining on metal or other material after it has been cast, cut or drilled.

CAD. Computer Assisted Design.

calcium silicate. Symbol: CaSIO³ (Wollastonite). A naturally occurring mineral found in metamorphic rocks, used as a reinforcing filler in polyester molding compounds, low-density polyethylene, and other thermosetting resins. It imparts smooth molded surfaces and low water absorption.

cammed ring. A type of backup ring whereby a tapered surface on the ring rides against another angled surface in a cam-like motion to close the extrusion-gap.|cantilever beam. A beam with one end projecting beyond the point of support, free to move in a vertical plane under the influence of vertical loads placed between the free end and the support.

cantilever beam spring. A type of spring used in seals. A metal strip stock is formed into a “V” shape which appears as two cantilever beams when viewed on the cross-section.

carbon fiber. An additive used in certain blends to increase wear resistance, extrusion resistance, and high-temperature capability.

cc/min. Cubic centimeters per minute.

CFC. Abbreviation for chlorofluorocarbon.

GLOSSARY


Backup | CFC

backup, or backup ring. A ring, usually made of a harder material, placed behind the seal to support it under high-pressure or temperature conditions. Also see anti-extrusion ring.

bar. A unit of measure of pressure equal to 105 newtons per square meter of 0.987 standard atmospheres.

“B” diameter. The larger of the two mating-surface diameters that make up the seal gland. The housing diameter when designing a rod seal, or the bore diameter when designing a piston seal.

bend point. That point in a lip design where the sealing surface, changing the lip orientation by 90º

benzene. A clear, colorless, flammable liquid C6H6 derived from petroleum and used in, or to manufacture a wide variety of chemical products including detergents, insecticides, and motor fuels. Also called “benzol”. Also see hydrocarbon.

bidirectional. Operating in two directions at once, such s bidirectional pressure. A seal which is bidirectional can seal two different media, or media acting from two opposing directions, especially when the pressure differential switches from one side of the seal to the other.

blend. 1. To combine or mix so as to render the constituent parts indistinguishable from one another. 2. That which is blended, a mixture. Blend typically refers to a seal material made with a base resin such as PTFE compounded with fillers such as carbon or graphite.

blended radius. A rounded corner, such as on the edge of a shaft, which has been smoothed to provide an easier surface for installing the shaft into the seal.

bore. A hole or passage made as if by drilling. The interior diameter of a hole, tube, cylinder or the like. In a piston-seal gland, the OD of the seal runs against the bore.

breakout friction. The initial frictional force between two unmoving surfaces which must be overcome to get one surface into motion against the other.

Buna-N. See acrylonitrile-butadiene copolymers.

burnish. To polish, smooth, or make glossy as if by rubbing.

burr. A rough edge or area remaining on metal or other material after it has been cast, cut or drilled.

CAD. Computer Assisted Design.

calcium silicate. Symbol: CaSIO³ (Wollastonite). A naturally occurring mineral found in metamorphic rocks, used as a reinforcing filler in polyester molding compounds, low-density polyethylene, and other thermosetting resins. It imparts smooth molded surfaces and low water absorption.

cammed ring. A type of backup ring whereby a tapered surface on the ring rides against another angled surface in a cam-like motion to close the extrusion-gap.|cantilever beam. A beam with one end projecting beyond the point of support, free to move in a vertical plane under the influence of vertical loads placed between the free end and the support.

cantilever beam spring. A type of spring used in seals. A metal strip stock is formed into a “V” shape which appears as two cantilever beams when viewed on the cross-section.

carbon fiber. An additive used in certain blends to increase wear resistance, extrusion resistance, and high-temperature capability.

cc/min. Cubic centimeters per minute.

CFC. Abbreviation for chlorofluorocarbon.

CGS | CPS

cgs. Centimeter-gram-second. Of relating to, or being a system of units based upon the centimeter as the unit of length, the gram as the unit of mass, and the mean solar second as the unit of time.

chamfer. 1. To cut off the edge or corner of; bevel. 2. A flat surface made by cutting off the edge or corner of something, such as the end of a shaft or entrance to a housing or bore.

chlorofluorocarbons. Chemicals containing only chlorine, fluorine, and carbon, eg. Freon®.

chrome plating. An electrolytic process of depositing chromium on metals either as a protection against corrosion or to increase the surface-wearing qualities. Also see hard chrome and thin-dense chrome.

chromium oxide. An extremely hard coating applied by a thermal-spray-coating process to improve wear resistance of moving parts.

CLA. Center Line Average. A type of surface finish measurement, the same as Ra and AA.

clearance fit. A condition where one mechanical part is fitted into another in such a way as to leave a small gap or clearance between the parts. Compare interference fit.

clearance-gap. See extrusion-gap.

clearance-seal. A type of seal which does not make direct positive contact with its mating surface. Typically there is a small clearance, or a series of clearances between the seal and its mating surface, which create pressure drops to reduce the flow of a fluid past the seal. Compare positive seal.

coating. A thin layer of material covering something else. Examples: a thin layer of metal applied to a shaft or bore surface to increase hardness and wear resistance, or a Teflon® coating for chemical compatibility or self-lubricating properties.

coefficient. A numerical measure of a physical or chemical property that is constant for a system under specified conditions.

coefficient of friction. The numerical constant expressing the ratio of the force required to overcome friction in order to slide an object along a surface, and the mass of that object. For example: a ten-pound mass resting on a specified surface and required 5 pounds of linear force to move it has a coefficient of friction of 0.5 on that surface.

CNC. Abbreviation for Computer Numerically Controlled. CNC refers to machining equipment where tool motion and spindle speeds are controlled by a computer program.

cold drawn. Drawn or pulled, as a wire through a die, without prior heating.

cold flow. Distortion of a material under load (such as a plastic seal molding itself to the shape of the gland due to media pressure). Also see creep.

cold work. The deliberate deformation of a metal at relatively low temperatures to improve strength or surface hardness.

compound. A combination of two or more elements or parts. Example: Tucson compounds are a combination of PTFE and various reinforcing agents such as glass, graphite, etc.

compression molding. The method of molding a material in a confined cavity by applying pressure and usually heat.

compression set. A permanent deformation, or set, resulting from compressive stress.

counterbore. A flat-bottomed, cylindrical recess, normally intended to permit the head of a fastening device, such as a bolt, to lie recessed in the part. |cpm. Cycles per minute. In reciprocating service a cycle includes one complete execution of the forward and backward stroke of a rod or piston. CPM designates the number of such cycles completed in one minute. Also see cycle rate.

cps. Cycles per second. Also see hertz.

GLOSSARY


Creep | E-Gap

creep. The time-dependent part of strain resulting from stress.

cross-section. 1. A section formed by a plane cutting through an object, usually at right angles to an axis. 2. A piece so cute or the graphic representation of such a piece.

CRS. Cold-rolled steel.

cryogenic. Of or relating to cryogenics. Cryogenic temperature typically refers to a very low temperature below about -200º F.

cryogenics. The science of low-temperature phenomena.

cycle rate. The rate at which a piston, rod or other device reciprocates, generally stated in cycles per minute (cpm) or cycles per second (ops or hertz).

dead volume. Also dead space. The unfilled area of a pump or seal cavity where air or other fluids can be trapped reducing the pump’s efficiency.

deflection. 1. The movement of a structure or structural part as a result of stress. 2. The deviation from zero shown by the indicator of a measuring instrument.

degradation. A deleterious change in the chemical structure, physical properties, or appearance of a plastic.

degrees of rotation. The total number of radial degrees (typically between 0 and 360) that an oscillatory shaft moves in one direction before reversing its motion.

Delrinº. A registered trademark of E.I. Dupont for their acetal resins which are crystalline thermoplastic homopolymers made by polymerization of formaldehyde. They are characterized by high mechanical strength and rigidity, low friction, resistance to moisture, fuels, and solvents; and wear resistance in load-bearing applications.

diametral clearance. Also diametrical clearance. The gap between two cylindrical metal surfaces, measured as the difference between the diameter of the inner piece and the diameter of the cylinder in which it rides.

diametral interference. See seal interference.

differential pressure. The difference in pressure from one side of a seal to the other. .

dry service. Dry means free from liquid or moisture; not wet, damp or moistened. In sealing applications, dry service refers to sealing with a lack of lubricating fluid, making a high-wear condition.

duty cycle. Duty refers to the work capability of a machine under specified conditions. The duty cycle is the frequency and duration of times that a piece of equipment is in operation, as opposed to sitting idle. Example: a pump operates 7 days per week, 35 times per day, for 3 minutes each time.

dynamic. Of or pertaining to energy, force, or motion in relation to force. Moving. Opposite of static.

dynamic seal. A seal which sees relative motion on at least one surface, e.g. a rotary shaft seal or a reciprocating rod seal.

dynamic service. Service conditions in which the seal must handle relative motion on at least one surface. In dynamic service, friction and wear considerations come into play.

eccentricity. Misalignment of one part in relation to its own true center line or the center line of another part. Refers to the misalignment of a rod, piston, or rotary shaft in relation to a seal installed in the gland.

E-gap. See extrusion-gap.

GLOSSARY


Creep | E-Gap

creep. The time-dependent part of strain resulting from stress.

cross-section. 1. A section formed by a plane cutting through an object, usually at right angles to an axis. 2. A piece so cute or the graphic representation of such a piece.

CRS. Cold-rolled steel.

cryogenic. Of or relating to cryogenics. Cryogenic temperature typically refers to a very low temperature below about -200º F.

cryogenics. The science of low-temperature phenomena.

cycle rate. The rate at which a piston, rod or other device reciprocates, generally stated in cycles per minute (cpm) or cycles per second (ops or hertz).

dead volume. Also dead space. The unfilled area of a pump or seal cavity where air or other fluids can be trapped reducing the pump’s efficiency.

deflection. 1. The movement of a structure or structural part as a result of stress. 2. The deviation from zero shown by the indicator of a measuring instrument.

degradation. A deleterious change in the chemical structure, physical properties, or appearance of a plastic.

degrees of rotation. The total number of radial degrees (typically between 0 and 360) that an oscillatory shaft moves in one direction before reversing its motion.

Delrinº. A registered trademark of E.I. Dupont for their acetal resins which are crystalline thermoplastic homopolymers made by polymerization of formaldehyde. They are characterized by high mechanical strength and rigidity, low friction, resistance to moisture, fuels, and solvents; and wear resistance in load-bearing applications.

diametral clearance. Also diametrical clearance. The gap between two cylindrical metal surfaces, measured as the difference between the diameter of the inner piece and the diameter of the cylinder in which it rides.

diametral interference. See seal interference.

differential pressure. The difference in pressure from one side of a seal to the other. .

dry service. Dry means free from liquid or moisture; not wet, damp or moistened. In sealing applications, dry service refers to sealing with a lack of lubricating fluid, making a high-wear condition.

duty cycle. Duty refers to the work capability of a machine under specified conditions. The duty cycle is the frequency and duration of times that a piece of equipment is in operation, as opposed to sitting idle. Example: a pump operates 7 days per week, 35 times per day, for 3 minutes each time.

dynamic. Of or pertaining to energy, force, or motion in relation to force. Moving. Opposite of static.

dynamic seal. A seal which sees relative motion on at least one surface, e.g. a rotary shaft seal or a reciprocating rod seal.

dynamic service. Service conditions in which the seal must handle relative motion on at least one surface. In dynamic service, friction and wear considerations come into play.

eccentricity. Misalignment of one part in relation to its own true center line or the center line of another part. Refers to the misalignment of a rod, piston, or rotary shaft in relation to a seal installed in the gland.

E-gap. See extrusion-gap.

Elastomer | Flange-Diameter

elastomer. 1. Any of various polymers having the elastic properties of natural rubber. 2. A macromolecular material that at room temperature returns rapidly to approximately its initial dimensions and shape after substantial deformation by a weak stress and release of the stress.

elongation. In tensile testing, elongation is the increase in length of a specimen at the instant before rupture occurs. Percent elongation is expressed as the increase in distance between two gauge marks at rupture, divided by the original distance between the marks, the quotient being multiplied by 100.

embrittlement. The condition of becoming brittle.

energizer. A device which transfers energy to something. In the seal, metal springs supply sealing energy to the plastic lips.

envelope. An enclosing or surrounding space. Refers to the space available in the hardware for designing seal glands.

EP. See ethylene-propylene rubber.

EPA. Environmental Protection Agency. Responsible for developing and enforcing regulations concerning air quality, water quality, ozone protection, and related issues.

ethylene-propylene rubber. (EPR, EPM, EPDM) A group of elastomers obtained by the copolymerization of ethylene and propylene (EPM), or one of these two monomers and a third monomer such as diene (EPDM). Their properties are similar to those of natural rubber in many respects.

explosive decompression. Serious production problems and safety hazards can occur on offshore oil-and-gas rigs, where high-pressure fluids in wellheads, valves, and pipelines can permeate the surface of an elastomeric seal. When system pressure is rapidly released, the elastomer can experience a sudden degradation or complete failure, caused by the fluids trapped in the elastomer suddenly expanding and “exploding” the material.

external-face seal. A face seal which handles pressures acting on the outside diameter of the seal.

extrusion. 1. Deformation of a seal material caused by forcing it into a gap in the hardware under pressure. Extrusion increases at higher temperatures but can be minimized by reducing the gap in the hardware or using a separate backup ring. 2. A molding process in which heated or unheated plastic is forced through a shaping orifice (a die) in one continuously formed shape, as in film, sheet, rod or tubing.

extrusion-gap. Also called E-gap. The radial clearance, or gap in the hardware through which a seal can extrude under pressure.

face seal. A seal working against two faces, usually compressed like a gasket on the top and bottom surfaces, e.g. when sealing the lid of a pressure vessel. Compare radial seal.

fatigue. Weakness in metal, wood or other material resulting from prolonged stress.

FDA. Food and Drug Administration. Responsible for developing and enforcing regulations concerning safety of foods, drugs, food-handling equipment, etc.

feet per minute. Abbr. fpm. The distance in feet traveled in one minute. Example: a piston with a 3 inch stroke, moving at a rate of 10 cpm has a surface speed of 5 fpm. Also see sfpm.

FEP. See fluorinated-ethylene propylene.

fill. A finely processed material (such as glass fiber, carbon, or graphite) added to a base-polymer resin (such as PTFE) to improve physical properties or performance. Also called a filler.

finish. See surface finish.

flange. A protruding rim, edge, rib or collar, as on a wheel or pipe shaft, used to strengthen an object, hold it in place, or attach it to aanother object.

flange diameter. The diameter of the outer edge of a flange.

GLOSSARY


Fluid | Groove width

fluid. A liquid, gas or any substance that is regarded as existing as a continuum characterized by low resistance to flow and the tendency to assume the shape of its container.

fluorinated ethylene propylene. Abbr. FEP. This member of the fluorocarbon family of plastics is a copolymer of tetrafluorethylene and hexafluoropropylene, processing most of the desirable properties of PTFE but having a melt viscosity low enough for processing in conventional thermoplastic molding or extrusion equipment.

fluorocarbons, or fluorocarbon resins. Thermoplastic resins chemically similar to the polyolefins, with all of the hydrogen atoms replaced with fluorine atoms. They are made from monomers composed only of fluorine and carbon. The main members of the fluorocarbon-resin family are polytetrafluoroethylene (PTFE), fluorinated-ethylene propylene (FEP), and polyhexafluoro-propylene.

fluoroelastomers. Elastomer compounds (such as Du Pont’s Viton®) containing fluorine, to improve corrosion resistance and high-temperature resistance.

fluoroplastics. The ASTM term for plastics based on polymers with monomers containing one or more atoms of fluorine or copolymers of such monomers, the fluorine-containing monomer(s) being in greatest amount by mass.

fluoropolymer. Another term for fluoroplastics.

foot-pound. A unit of torque equal to the work done by a force of one pound acting through a distance of one foot in the direction of theforce of one pound acting through a distance of one foot in the direction of the force.

fpm. Feet per minute. A measurement of velocity in terms of the distance travelled in feet over a period one minute.

free height. The measured height of a spring in the unloaded, free state.

Freonº. A registered trademark of Du Pont for their trichloro-fluoromethane CCI³F (Freon 11) blowing agent for foam plastics; dichlorodifluoromethane CCI²F² (Freon 12) aerosol propellant and refrigerant; and other Freon compounds used for various purposes.

friction. A force tangential to the common boundary of two bodies in contact that resists the motion or tendency to motion of one relative to the other.

ft-lbs. See foot-pounds.

gasket. Any of a wide variety of seals or packages used between matched machine parts or around pipe joints to prevent the escape of a gas or fluid.

gland. A general term used for various types of cavity into which a seal, bearing, or other item is installed. There are several types of seal gland. For rod seals, the seal gland is also called a housing. For piston seals, the gland may be called a seal groove, or piston groove.

gland ID. That diameter of the seal gland which contacts the ID of the seal; for piston seals it would be the piston groove diameter; for rod or shaft seals it would be the rod or shaft diameter.

gland OD. That diameter of the seal gland which contacts the OD of the seal; for piston seals it would be the bore diameter.

gm-cm. Gram-centimeter. A unit of torque.

graphite. A crystalline form of carbon with atoms arranged hexagonally, characterized by a soft, greasy feel. It occurs naturally, and is also produced synthetically by heating petroleum coke or other organic materials under controlled atmospheric conditions. In powder form, graphite is used as a lubricating filler for fluorocarbon resins.

groove. A narrow funnel or channel cut into the hardware to house the seal. Also see piston groove.

groove depth. The distance in the radial direction of the channel cut into the hardware.

groove width. The distance in the axial direction of the channel cut into the hardware.

GLOSSARY


Fluid | Groove width

fluid. A liquid, gas or any substance that is regarded as existing as a continuum characterized by low resistance to flow and the tendency to assume the shape of its container.

fluorinated ethylene propylene. Abbr. FEP. This member of the fluorocarbon family of plastics is a copolymer of tetrafluorethylene and hexafluoropropylene, processing most of the desirable properties of PTFE but having a melt viscosity low enough for processing in conventional thermoplastic molding or extrusion equipment.

fluorocarbons, or fluorocarbon resins. Thermoplastic resins chemically similar to the polyolefins, with all of the hydrogen atoms replaced with fluorine atoms. They are made from monomers composed only of fluorine and carbon. The main members of the fluorocarbon-resin family are polytetrafluoroethylene (PTFE), fluorinated-ethylene propylene (FEP), and polyhexafluoro-propylene.

fluoroelastomers. Elastomer compounds (such as Du Pont’s Viton®) containing fluorine, to improve corrosion resistance and high-temperature resistance.

fluoroplastics. The ASTM term for plastics based on polymers with monomers containing one or more atoms of fluorine or copolymers of such monomers, the fluorine-containing monomer(s) being in greatest amount by mass.

fluoropolymer. Another term for fluoroplastics.

foot-pound. A unit of torque equal to the work done by a force of one pound acting through a distance of one foot in the direction of theforce of one pound acting through a distance of one foot in the direction of the force.

fpm. Feet per minute. A measurement of velocity in terms of the distance travelled in feet over a period one minute.

free height. The measured height of a spring in the unloaded, free state.

Freonº. A registered trademark of Du Pont for their trichloro-fluoromethane CCI³F (Freon 11) blowing agent for foam plastics; dichlorodifluoromethane CCI²F² (Freon 12) aerosol propellant and refrigerant; and other Freon compounds used for various purposes.

friction. A force tangential to the common boundary of two bodies in contact that resists the motion or tendency to motion of one relative to the other.

ft-lbs. See foot-pounds.

gasket. Any of a wide variety of seals or packages used between matched machine parts or around pipe joints to prevent the escape of a gas or fluid.

gland. A general term used for various types of cavity into which a seal, bearing, or other item is installed. There are several types of seal gland. For rod seals, the seal gland is also called a housing. For piston seals, the gland may be called a seal groove, or piston groove.

gland ID. That diameter of the seal gland which contacts the ID of the seal; for piston seals it would be the piston groove diameter; for rod or shaft seals it would be the rod or shaft diameter.

gland OD. That diameter of the seal gland which contacts the OD of the seal; for piston seals it would be the bore diameter.

gm-cm. Gram-centimeter. A unit of torque.

graphite. A crystalline form of carbon with atoms arranged hexagonally, characterized by a soft, greasy feel. It occurs naturally, and is also produced synthetically by heating petroleum coke or other organic materials under controlled atmospheric conditions. In powder form, graphite is used as a lubricating filler for fluorocarbon resins.

groove. A narrow funnel or channel cut into the hardware to house the seal. Also see piston groove.

groove depth. The distance in the radial direction of the channel cut into the hardware.

groove width. The distance in the axial direction of the channel cut into the hardware.

Halocarbon plastics | Kilogram

halocarbon plastics. A term listed by ASTM for polymers containing only carbon and one or more halogens.

halogenate. To treat or cause to combine with a halogen.

halogen. The elements fluorine, chlorine, bromine, iodine, and astatine.

hardness. The relative resistance of a metal to denting, scratching, or bending. Hardness of metallic shafts is typically expressed as arelative value from the Rockwell C or Brinell hardness scales.

hertz. Abbr. Hz. A unit of frequency equal to one cycle per second.

high-modulus. Refers to those materials having a relatively high modules of elasticity (more rigid, harder plastics such as PEEK), as compared to softer, more flexible seal or backup-ring materials such as Teflonº or Nylonº.

homopolymer. A polymer resulting from the polymerization of a single monomer; a polymer consisting substantially of a single type of repeating unit.

housing. A frame, bracket or box for holding or protecting a mechanical part. Examples: wheel housing, bearing housing, seal housing.

H²S. See hydrogen sulfide.

hydrocarbon. Any of numerous organic compounds, such as benzene and methane, that contain only carbon and hydrogen.

hydrogen sulfide. Symbol H²S. A colorless, flammable, poisonous compound having a characteristic rotten-egg odor, and used as a precipitator, purifier, and reagent. Also see sour gas.

hydrophobicity. The state of being antagonistic to, shedding, not tending to combine with, or incapable of dissolving in water. Refers to a material property-particularly of PTFE compounds-which prevents the formation of a fluid film on the surface of the material when sealing water-based media.

Hz. See hertz.

ID. Inside diameter. A measurement taken from a point on the inner wall surface of a circular object, along a straight line through the center of the object to a point on its opposite inner-wall surface.

inch-ounce. Abbr. in-oz. A unit of work equal to the work done by a force of one ounce acting through a distance of one inch in the direction of the force.

in. oz. Plural in ozs. See inch-ounce.

interference. The dimensional intrusion of one mechanical part into another. See also interference fit, and seal interference.

interference fit. The condition whereby one part slightly oversized is fitted tightly into another. Example, a 1.000 inch pin pressed into a .998 inch hole has an interference fit of .002 inches. A seal installed in a gland usually has an interference fit. Compare clearance fit.

internal face seal. A face seal that handles pressure acting on the inside diameter of the seal.

Kalrez®. A registered trademark of E.I. Du Pont for their corrosion-resistant, high-temperature, perfluorinated elastomer compound.

Kel-F™. A trademark of 3M Corporation for their melt-processable fluoropolymer PCTFE. See Polychlorotrifluoroethylene.

key-way. A slot in a wheel hub or shaft for a key. The key connects the shaft to a rotary-drive mechanism.

kilogram. Abbr. kg. 1. The fundamental unit of mass in the international System, about 2.2046 pounds. 2. The force equal to a kilogram weight; that is, the product of a kilogram mass with the acceleration of gravity.

GLOSSARY


Kilorad | Monomer

kilorad. One thousand rads.

leakage. Passage of a fluid medium or other material past a seal.

leakage rate. The rate at which a fluid medium or other material passes a seal.

line-to-line fit. Also called line-fit. An assembly where one part fits into another with a close sliding fit, without significant clearance or interference.

lip. Refers to the rim edge of a seal, especially at the point where sealing contact is formed against the mating surface.

load. The overall force to which a structure is subjected in supporting a weight or mass, or in resisting externally applied forces. Also see spring load.

lubricant. Any of various usually oily liquids or solids, such as grease, machine oil, or graphite, that reduce friction, heat, and wear when applied as a surface coating to moving parts.

mating surface. The surface of a hardware component (such as a shaft, bore, etc.) that contacts the seal to prevent leakage. The qualities of the mating surface are important for their influence on seal performance.media. The fluids or other substances being sealed. Plural or medium.

megarad. One million rads, a unit of radiation dosage.

melt-processable. Said of thermoplastics which are processable into final shapes by methods employing heat, such as extrusion, injection molding, and hot compression molding.

memory. The tendency of a material to return to its original shape after release of a load that caused a deformation.

metal-encased. Enclosed in a metallic shell. Refers to a seal or lip designs which are surrounded by a metal case that is press-fit into a housing.

meter. Abbr. m. The fundamental unit of length (equivalent to 39.37 inches) in the metric system.

metric. Designating, pertaining to, or using the metric system, a decimal system of weights and measures based on the meter as a unit length and the kilogram as a unit mass.

MIL-G-5514. Mil-G-5514F “Gland Design: Packings, Hydraulic General Requirements For” is the military specification which gives basic design criteria for seal glands in hydraulic equipment. All of the grooves specified are the solid (one-piece) style. The specification for O-ring-seal groove dimensions includes a list of standard sizes designated by dash numbers -006 through -460. The gland diameters vary slightly from standard inch-fractional sizes. Compare inch-fractional.

mks. Meter-kilogram-second. Of relating to, or being a system of units based upon the meter as the unit of length, the kilogram as the unit of mass, and the mean solar second as the unit of time.

mm. Abbreviation for millimeter. A unit of length equal to one thousandth of a meter or 0.0394 inch.

modulus of elasticity. The stress required to produce a given strain depends on the nature of the material under stress. The ratio of stress to strain, or the stress per unit strain, is called an elastic modulus of the material. The larger the elastic modulus, the greater the stress needed for a given strain. Also see high modulus.

molybdenum disulfide. Symbol: MoS² Also molybdic sulfide, molybdenum sulfide. A white, shiny crystalline material used as a lubricant in nylon, fluorocarbons and polystyrene to reduce wear and friction. It also acts as a strength-improving reinforcement.

monomer. A relatively simple compound, usually containing carbon and of low molecular weight, which can react to form a polymer by combination with itself or with other similar molecules or compounds.

GLOSSARY


Kilorad | Monomer

kilorad. One thousand rads.

leakage. Passage of a fluid medium or other material past a seal.

leakage rate. The rate at which a fluid medium or other material passes a seal.

line-to-line fit. Also called line-fit. An assembly where one part fits into another with a close sliding fit, without significant clearance or interference.

lip. Refers to the rim edge of a seal, especially at the point where sealing contact is formed against the mating surface.

load. The overall force to which a structure is subjected in supporting a weight or mass, or in resisting externally applied forces. Also see spring load.

lubricant. Any of various usually oily liquids or solids, such as grease, machine oil, or graphite, that reduce friction, heat, and wear when applied as a surface coating to moving parts.

mating surface. The surface of a hardware component (such as a shaft, bore, etc.) that contacts the seal to prevent leakage. The qualities of the mating surface are important for their influence on seal performance.media. The fluids or other substances being sealed. Plural or medium.

megarad. One million rads, a unit of radiation dosage.

melt-processable. Said of thermoplastics which are processable into final shapes by methods employing heat, such as extrusion, injection molding, and hot compression molding.

memory. The tendency of a material to return to its original shape after release of a load that caused a deformation.

metal-encased. Enclosed in a metallic shell. Refers to a seal or lip designs which are surrounded by a metal case that is press-fit into a housing.

meter. Abbr. m. The fundamental unit of length (equivalent to 39.37 inches) in the metric system.

metric. Designating, pertaining to, or using the metric system, a decimal system of weights and measures based on the meter as a unit length and the kilogram as a unit mass.

MIL-G-5514. Mil-G-5514F “Gland Design: Packings, Hydraulic General Requirements For” is the military specification which gives basic design criteria for seal glands in hydraulic equipment. All of the grooves specified are the solid (one-piece) style. The specification for O-ring-seal groove dimensions includes a list of standard sizes designated by dash numbers -006 through -460. The gland diameters vary slightly from standard inch-fractional sizes. Compare inch-fractional.

mks. Meter-kilogram-second. Of relating to, or being a system of units based upon the meter as the unit of length, the kilogram as the unit of mass, and the mean solar second as the unit of time.

mm. Abbreviation for millimeter. A unit of length equal to one thousandth of a meter or 0.0394 inch.

modulus of elasticity. The stress required to produce a given strain depends on the nature of the material under stress. The ratio of stress to strain, or the stress per unit strain, is called an elastic modulus of the material. The larger the elastic modulus, the greater the stress needed for a given strain. Also see high modulus.

molybdenum disulfide. Symbol: MoS² Also molybdic sulfide, molybdenum sulfide. A white, shiny crystalline material used as a lubricant in nylon, fluorocarbons and polystyrene to reduce wear and friction. It also acts as a strength-improving reinforcement.

monomer. A relatively simple compound, usually containing carbon and of low molecular weight, which can react to form a polymer by combination with itself or with other similar molecules or compounds.

MoS² | Piston seal

MoS². See molybdenum disulfide.

MPa. Megapascal. One million pascals. See pascal.

newton. The unit of force which when, applied to a body having a mass of one kilogram gives it an acceleration of one meter per secondper second.

nibbling. Under pressure a portion of an elastomatic O-ring or other type of seal can extrude into the clearance-gap. When rod of piston motion occurs, the seal material – pinched between two pieces of hardware – is “bitten off”. This process is called nibbling.

nitrile. Refers to nitrile rubber, an elastomeric (synthetic rubber) compound containing trivalent nitrogen (N³) in a cyanogen group. See also Buna-N.

nominal. Of being, or related to a designated or theoretical size that may vary from the actual. Example: the 200 series seal has a nominal cross-section of 1/8 inch (.125) while the actual cross-section is closer to .152 inch.

OD. Outside diameter. A measurement taken from a point on the outer surface of a round object, along a straight line through the center of the object to a point on its opposite outer surface.

one-piece gland. See solid gland.

open gland. A type of seal housing consisting of a one-piece groove that is open on one side.

organic. Of, or designating carbon compounds.

O-ring. A ring, typically made of synthetic rubber, used as a seal.

oscillate. To swing back and forth with a steady, uninterrupted rhythm. Refers to shafts which rotate back and forth rather than continuously in one direction. Compare reciprocate.

oscillatory. Pertaining to a back and forth rotary-shaft motion, usually less than 360º before reversing directions.

Pa. See pascal.

pascal. The SI unit of pressure is one pascal, equal to one Newton per square meter. A related unit is one bar, defined as 105 Pa.

PEEK. See polyetheretheketone.

perfluorinated. Thoroughly or completely fluorinated. Fluorinate means to treat or case to combine with fluorine. A perfluorinated elastomer is a synthetic rubber enhanced by combining with fluorine, to produce a compound with better high-temperature properties and high corrosion resistance.

perfluoroalkoxy resins. Abbr. PFA. A class of melt-processable fluoroplastics in which perfluoroalkyl side chains are connected to the carbon-fluorine backbone of the polymer through flexible oxygen linkages. Introduced by Du Pont in 1972, PFA resins have the desirable properties typical of fluoroplastics plus superior creep resistance, and are more easily processed by extrusion and injection molding.

perfluoroeslastomer. Introduced by Du Pont in early 1977 under the trademark Kalrez®, this elastomer is said to combine the properties of a conventional fluoroeslastomer such as Du Pont’s Viton® with those of fluorocarbon plastics like PTFE. Applications include gaskets, O-rings, and other parts that must withstand temperatures to 550ºF, and have high resistance to chemicals and solvents.

pistons. A sliding piece, moved by or moving against fluid pressure, usually consisting of a short cylinder fitting closely within a cylindrical vessel along which it moves back and forth.

piston groove. A narrow channel machined into the surface of a piston to house a seal or wear-ring.

piston seal. A seal mounted in a groove on a piston and having a dynamic sealing surface against the side of a cylinder bore.

GLOSSARY


Play | Reciprocate

play. Movement, or space for movement, of mechanical parts.

polish. To make smooth and glossy, usually by friction. Burnish.

polyamide. A compound characterized by more than one amide group, especially a polymeric amide (such as nylon).

polyetheretherketone. Abbr. PEEK. A high-modulus, high-temperature engineering thermoplastic. It has very good chemical compatibility, high strength and wear-resistance, making it an excellent backup ring or bearing material.

polyether sulfone. Abbr. PES. A high-temperature engineering thermoplastic consisting of repeating phenyl groups linked by thermally stable ether and sulfone groups. The material is highly wear-resistant, tough, rigid, strong, has outstanding long-term resistance to creep, and is capable of being used continuously under load at temperatures of 358ºF, and higher in low-stress applications.

Polyhexafluoropropylene. A fluorocarbon resin based on the gas C³F5. It can be copolymerized with tetrafluoroethylene to form the FEP family of fluorocarbons.

polyimide. A highly-temperature thermoplastic with excellent wear properties, and excellent strength and rigidity.

polymer. A chemical compound or mixture of compounds formed by polymerization and consisting essentially of repeating structural units.

polymerization. A chemical reaction in which two or more small molecules combine to form larger molecules that contain repeating structural units of the original molecules.

press-fit. An assembly of mechanical components whereby one piece, due to dimensional interference with another piece, fits so tightly that it must be pressed into place with some force. Also called interference fit. Compare clearance fit and line-to-line fit.

pressure. The application of continuous force by one body upon another that it is touching; compression.

pressure-actuated. Put into action or motion by means of pressure. Refers to the seal design feature whereby the sealing lips are forced against the mating surface by the action of fluid pressure.

psi. Pounds per square inch. A unit of measure for pressure acting on an area.

qc. Quality control.

rad. A unit of energy absorbed from ionizing radiation, equal to 100 ergs per gram of irradiated material.

radial. 1. Radiating from or converging to a common center. 2. Moving or directed along a radius. Refers to a line from the center of a rod, shaft, or other part outwards in the radial direction. Compare axial.

radial clearance. Also called E-gap, or extrusion-gap. It is the distance of a gap normally equal to 1 / 2 the diametral clearance, although it can be greater (up to the full diametral clearance) due to sideloading, and depending on the quality of bearings or bushings. See also diametral clearance.

radial envelope. The total radial space available to the seal designer for placement of a seal assembly in the hardware.

radial interference. The dimensional interference of a seal in relation to the mating surfaces of the seal gland as measured across one radial cross-section.

radial seal. A seal that is compressed in the radial direction, such as a rod or piston seal, as opposed to a face seal which is compressed in the axial direction.

radius. A line segment that joins the center of a circle with any point on its circumference.

reciprocate. To move back and forth alternately. Reciprocate usually refers to a linear back-and-forth motion, while oscillate refers to arotary back-and-forth motion.

GLOSSARY


Play | Reciprocate

play. Movement, or space for movement, of mechanical parts.

polish. To make smooth and glossy, usually by friction. Burnish.

polyamide. A compound characterized by more than one amide group, especially a polymeric amide (such as nylon).

polyetheretherketone. Abbr. PEEK. A high-modulus, high-temperature engineering thermoplastic. It has very good chemical compatibility, high strength and wear-resistance, making it an excellent backup ring or bearing material.

polyether sulfone. Abbr. PES. A high-temperature engineering thermoplastic consisting of repeating phenyl groups linked by thermally stable ether and sulfone groups. The material is highly wear-resistant, tough, rigid, strong, has outstanding long-term resistance to creep, and is capable of being used continuously under load at temperatures of 358ºF, and higher in low-stress applications.

Polyhexafluoropropylene. A fluorocarbon resin based on the gas C³F5. It can be copolymerized with tetrafluoroethylene to form the FEP family of fluorocarbons.

polyimide. A highly-temperature thermoplastic with excellent wear properties, and excellent strength and rigidity.

polymer. A chemical compound or mixture of compounds formed by polymerization and consisting essentially of repeating structural units.

polymerization. A chemical reaction in which two or more small molecules combine to form larger molecules that contain repeating structural units of the original molecules.

press-fit. An assembly of mechanical components whereby one piece, due to dimensional interference with another piece, fits so tightly that it must be pressed into place with some force. Also called interference fit. Compare clearance fit and line-to-line fit.

pressure. The application of continuous force by one body upon another that it is touching; compression.

pressure-actuated. Put into action or motion by means of pressure. Refers to the seal design feature whereby the sealing lips are forced against the mating surface by the action of fluid pressure.

psi. Pounds per square inch. A unit of measure for pressure acting on an area.

qc. Quality control.

rad. A unit of energy absorbed from ionizing radiation, equal to 100 ergs per gram of irradiated material.

radial. 1. Radiating from or converging to a common center. 2. Moving or directed along a radius. Refers to a line from the center of a rod, shaft, or other part outwards in the radial direction. Compare axial.

radial clearance. Also called E-gap, or extrusion-gap. It is the distance of a gap normally equal to 1 / 2 the diametral clearance, although it can be greater (up to the full diametral clearance) due to sideloading, and depending on the quality of bearings or bushings. See also diametral clearance.

radial envelope. The total radial space available to the seal designer for placement of a seal assembly in the hardware.

radial interference. The dimensional interference of a seal in relation to the mating surfaces of the seal gland as measured across one radial cross-section.

radial seal. A seal that is compressed in the radial direction, such as a rod or piston seal, as opposed to a face seal which is compressed in the axial direction.

radius. A line segment that joins the center of a circle with any point on its circumference.

reciprocate. To move back and forth alternately. Reciprocate usually refers to a linear back-and-forth motion, while oscillate refers to arotary back-and-forth motion.

Retainer | Sour Gas

retainer. Any device that holds a mechanical part (such as a seal or a bearing) in a particular place or position.

RMS. Root-mean-square. A measure of surface roughness. The term RMS, while continuing in use, is actually obsolete per ANSI B46 standard on surface texture. The modern term is Rq.

Rockwell hardness test. The Rockwell hardness tester is essentially a machine that measures hardness by determining the depth of penetration of a penetrator into the specimen under certain fixed conditions of test. The penetrator may be either a steel ball or a diamond sphero-conical point. The hardness number is related to the depth of indentation and the number is higher the harder the material.

rod. A slender, straight round bar. A rod is the same as a shaft. However, the term “rod” is typically used to refer to a reciprocating part, while “shaft” is used to refer to a rotary part.

rod seal. A seal mounted in a housing and having a dynamic mating surface against a reciprocating rod.

rotary. Of, pertaining to, causing, or characterized by rotation.

rotation. Motion in which the path of every point in the moving object is a circle or circular arc centered on a specified axis, especially on an internal axis. Example: the rotation of the earth.

rpm. Revolutions per minute. Unit of measure for rotary motion, designating the number of complete revolutions of an object over a period of one minute.

rq. Geometric-average roughness, or Root Mean Square (RMS) is the geometric-average height of roughness-component irregularities measured within a sampling length on a mechanical part. It is more sensitive to occasional highs and lows than Ra.

RTV. Room Temperature Vulcanizing. Refers to RTV silicone-gel two-component compounds. One component (a liquid or paste) cures with the addition of a second compound (a curing agent) to a strong, durable, resilient silicone-rubber.

Ryton®. A registered trademark of Phillips Petroleum Company for their PPS organic polymer. See polyphenylene sulfide.

running friction. Operating friction. The frictional force in effect between two surfaces already in motion, as apposed to breakout friction.

seal cross-section. The nominal distance from a point on the ID of a seal, along a radius to a point on the OD of the seal. Example: the 100 series seal has a nominal 3/32 inch cross-section.

seal interference. The difference in dimensions between the diameters of a seal and the diameters of its mating surfaces.

set. Strain remaining after complete release of the force producing the deformation. When a spring or seal “takes a set” it no longer returns to 100 % of its original free height.

shaft. A slender, straight round bar. A shaft is the same as a rod. However, the term “shaft” usually refers to a rotary part, while “rod” refers to a reciprocating part.

shaft seal. A seal mounted in a housing and having a dynamic contact surface against a rotary shaft.

sideload. Force applied to one side of a rod or shaft, which tends to movie it out of true alignment. Depending on the amount of sideload, it may distort the seal, interfere with sealing contact, cause leakage, or contribute to excessive wear.

silicone. Any of a group of semi-organic polymers based on the structural unit R²SiO where R is an organic group, characterized by wide-range thermal stability, high lubricity, extreme water repellance, and physiochemical inertness, used in adhesives, lubricants, protective coatings, paints, electrical insulation, synthetic rubber, and prosthetic replacements for bodily parts.

solid gland. A one-piece, nonseparable groove that houses a seal or wear-ring.

sour gas. Gas containing hydrogen sulfide, encountered in some oil-well-drilling operations. Usually combined with high temperatures and pressures in deep wells, it has corrosive effects on certain metals, elastomers, and plastics.

GLOSSARY


Spacer ring | Thermoset

spacer ring. A ring that separates two parts. In the lip design, a spacer ring keeps two sealing elements apart, or keeps a single sealingelement away from the face of the housing to allow space for the operation of the seal.

spline. Any of a series of projections on a shaft that fit into slots on a corresponding shaft, enabling both to rotate together from one drive mechanism.

static. Having no motion; at rest. Refers to a condition where no relative motion occurs between a seal and its mating surface, as opposed to dynamic.

static surface. 1. That surface of a seal or gland that sees no relative motion. In a piston-seal assembly the ID of the seal and the piston-groove surface are static surfaces. In a rod-seal assembly the OD of the seal and the inside of the housing are static surfaces.

step height. The distance from the base of the seal gland to the top of a radial protrusion of the hardware. The step retains the seal in a stepped gland.

stepped gland. A one-piece gland with a small step in the hardware on the pressure side of the groove, to retain the seal in the gland.

stick-slip. When a piston or rod moves a certain distance, sticks momentarily and then slips free, condition known as stick-slip is occurring. It is typically encountered when using elastomeric seals under conditions of less-than-ideal lubrication.

stress. An applied force or system of forces that tends to strain or deform a body.

stroke. A movement of a rod or piston from one end of the limit of its travel to the other. Two strokes make one cycle. See cpm.

stroke length. The length of linear travel of a rod or piston in one direction, forward or backward.

surface finish. The texture produced by the last treatment or coating on the surface of an object, especially on the mating surface contacted by the seal.

surface speed. The rate of motion measured on the outer surface of a rotary shaft or reciprocating rod, usually expressed in feet per minute.

Teflon®. A registered trademark of Du Pont for their fluoropolymer resins, films and fibers. The Teflon trademark is used in conjunction with three fluoropolymers, PTFE, PFA, and FEP.

temperature range. The temperature range of an application includes all operating temperatures from lowest to highest that a seal will be subjected to in actual service. The temperature range of a material or a device includes all temperatures at which the material or device is capable of functioning properly.

tensile. Of or pertaining to tension, the act of stretching or the condition of being stretched.

TFM. A variation of polytetrafluoroethylene with improved properties for special applications. It has the same friction, thermal, chemical, and electrical properties as PTFE, but lower deformation under load, and better wear-resistance.

thermal spray coatings. Various types of thermal-spray processes and used to deposit extremely hard and wear-resistant metal-oxide, carbide, or ceramic coatings on critical parts (such as rotary-shafts). The coating materials are typically heated to very high temperatures and sprayed at high velocity. Also see plasma-spray coating, tungsten carbide, aluminum oxide, and chromium oxide.

thermoplastic. 1. Becoming soft when heated and hardening when cooled. 2. A thermoplastic resin, such as polystyrene or polyethylene, which repeatedly can be softened by heating and hardened by cooling, and in the softened state can be shaped by flow into articles by molding or extrusion.

thermoplastic elastomer. Abbr. TPE. A class of material combining the properties of elastomers with engineering thermoplastics.

thermoset. A plastic that, after having been cured by heat or other means, is substantially infusible and insoluble.

GLOSSARY


Spacer ring | Thermoset

spacer ring. A ring that separates two parts. In the lip design, a spacer ring keeps two sealing elements apart, or keeps a single sealingelement away from the face of the housing to allow space for the operation of the seal.

spline. Any of a series of projections on a shaft that fit into slots on a corresponding shaft, enabling both to rotate together from one drive mechanism.

static. Having no motion; at rest. Refers to a condition where no relative motion occurs between a seal and its mating surface, as opposed to dynamic.

static surface. 1. That surface of a seal or gland that sees no relative motion. In a piston-seal assembly the ID of the seal and the piston-groove surface are static surfaces. In a rod-seal assembly the OD of the seal and the inside of the housing are static surfaces.

step height. The distance from the base of the seal gland to the top of a radial protrusion of the hardware. The step retains the seal in a stepped gland.

stepped gland. A one-piece gland with a small step in the hardware on the pressure side of the groove, to retain the seal in the gland.

stick-slip. When a piston or rod moves a certain distance, sticks momentarily and then slips free, condition known as stick-slip is occurring. It is typically encountered when using elastomeric seals under conditions of less-than-ideal lubrication.

stress. An applied force or system of forces that tends to strain or deform a body.

stroke. A movement of a rod or piston from one end of the limit of its travel to the other. Two strokes make one cycle. See cpm.

stroke length. The length of linear travel of a rod or piston in one direction, forward or backward.

surface finish. The texture produced by the last treatment or coating on the surface of an object, especially on the mating surface contacted by the seal.

surface speed. The rate of motion measured on the outer surface of a rotary shaft or reciprocating rod, usually expressed in feet per minute.

Teflon®. A registered trademark of Du Pont for their fluoropolymer resins, films and fibers. The Teflon trademark is used in conjunction with three fluoropolymers, PTFE, PFA, and FEP.

temperature range. The temperature range of an application includes all operating temperatures from lowest to highest that a seal will be subjected to in actual service. The temperature range of a material or a device includes all temperatures at which the material or device is capable of functioning properly.

tensile. Of or pertaining to tension, the act of stretching or the condition of being stretched.

TFM. A variation of polytetrafluoroethylene with improved properties for special applications. It has the same friction, thermal, chemical, and electrical properties as PTFE, but lower deformation under load, and better wear-resistance.

thermal spray coatings. Various types of thermal-spray processes and used to deposit extremely hard and wear-resistant metal-oxide, carbide, or ceramic coatings on critical parts (such as rotary-shafts). The coating materials are typically heated to very high temperatures and sprayed at high velocity. Also see plasma-spray coating, tungsten carbide, aluminum oxide, and chromium oxide.

thermoplastic. 1. Becoming soft when heated and hardening when cooled. 2. A thermoplastic resin, such as polystyrene or polyethylene, which repeatedly can be softened by heating and hardened by cooling, and in the softened state can be shaped by flow into articles by molding or extrusion.

thermoplastic elastomer. Abbr. TPE. A class of material combining the properties of elastomers with engineering thermoplastics.

thermoset. A plastic that, after having been cured by heat or other means, is substantially infusible and insoluble.

GLOSSARYThermosetting | Wear pattern

thermosetting. Permanently hardening or solidifying on being heated, said of certain synthetic resins.

TIR. Total Indicator Reading. Refers to the maximum deviation from a true center line of the surface of a round shaft during rotation, as measured with a dial indicator, and typically expressed in thousandths of an inch.

tolerance. The permissible deviation from a specified value of a structural dimension. Example: A shaft with a 1.000 +/- .002 inch diameter can measure anywhere from 0.998 to 1.002 inches and be considered within tolerance.

torque. Torque is defined as the movement of a force, a measure of its tendency to produce torsion and rotation about an axis, equal to the vector product of the radius vector from the axis of rotation to the point of application of the force, by the force applied.

torsion. 1. The act of twisting or turning. 2. The condition of being twisted or turned. 3. The stress caused when one end of an object is twisted in one direction and the other end is held motionless or twisted in the opposite direction.

TPE. See thermoplastic elastomer.

U-cup. A seal configuration roughly resembling a “U” shape when viewed on the cross-section.

UHMWPE. Also UHMWP. See ultrahigh-molecular-weight polyethylene.

µin. Microinch(es). A microinch is one millionth of an inch.

ultra-high-molecular-weight polyethylene. Abbr. UHMWP or UHMWPE, a polyethylene resin having a molecular weight of 3.2 to 6 million. The properties of UHMWPE include outstanding abrasion resistance, a nonstick surface, and excellent chemical compatibility.

µm. Micrometer(s). A micrometer is one millionth of a meter.

vacuum. Containing air or gas at reduced pressure, typically less than atmospheric.

vapor pressure. The pressure of vapor in equilibrium or solid at any temperature is called the vapor press substance at that temperature.

virgin material. A plastic material in the form of pellets, granules, powder, or liquid that has not been subjected to use or processing other than that required for its initial manufacture.

viscosity. The property of resistance of flow exhibited within the body of a material.

Viton®. A registered trademark of Du Pont for a series of fluoroelastomers used as gaskets, O-rings, oil seals, etc. Valuable properties include high-temperature capability and resistance to steam, hot water and chemicals.

vulcanize. To improve the strength, resiliency, and freedom from stickiness and odor of (rubber) by combining with sulfur or other additives in the presence of heat and pressure.

wear life. The service life of a seal or other device during which the critical components eventually wear away.

wear pattern. A distinguishing set of marks or other evidences of wear obtained over a period of time in service, which reveal a pattern ofstresses applied to a seal, bearing, or other device.

.

888.692.7114www.gulfrubberco.com

o-rings catalog print.pdf · 2019-03-08 · in seal and gland design, the axial direction is...

Documents