Parco O-Rings— PURPOSE OF BROCHURE

designed as a quick and easy reference for proper selection of an 0-ring to match your particular needs. The brochure contains information on 0-ring size and installation data, 0-ring compounds and their compatibility with fluids, and a chart of popular military/aerospace specifications.
YOUR PARCO DISTRIBUTOR
equipped to provide you with full service. He is prepared to assist you in the selection of the proper seal, but that’s only the beginning. He stocks a full range of Parco sealing products and can provide a local safety stock for your specific needs. In addition, most of our distributors are equipped to provide special packaging or product identification tailored to your needs.
Depend on him. He is a local independent businessman who cares very much about helping you with your complete sealing needs.
Parco seahng products he carries include:
0-Rings 369 standard sizes, hundreds of specials.
0-Ring Kits The 30 most popular sizes. 380 rings in all.
BACK0’s® Hard rubber contoured backup rings for seal pressures exceeding 1500 psi.
T-Seals Rubber seal and nylon or teflon backup combination for long-stroke, high-pressure applications. Fits in standard 0-ring groove.
Quality, delivery, technical strength, full line sealing capability.. the things that matter most to you are our most important concerns.
O-ring sizes
DO-ring sizes are described by l.D. (in- - side diameter) and W (cross-section). There are 369 standard size 0-rings ranging in size from .029” ID by .040” cross section to an 0-ring with a 25.940’ ID by .275” cross section. There are 11 9 standard size ID’s available in the 5 popular cross-section diameters (.070, .103, .139, .210 or .275 inches). These standard size 0-rings are listed on the 0-ring size chart on pages 4 through 7 of this booklet. 0-ring sizes are generally described by “dash number”. Parco’s PRP-568 “dash number” designation is equivalent to Aerospace Standard (AS) 568A or “2 dash” series designations used within the industry.
While only standard size 0-rings are listed, Parco has hundreds of special size 0-ring tools. It’s likely we already have the 0-ring size you need. If not, we are equipped to build new tooling to produce your 0-ring.
0-RING INSTALLATION dicated the installation dimensions. A nominal 1 “ID x 1 Y4”OD 0-ring (PRP568-2 1 4), for instance, would be installed on a 1” piston groove diameter in a 11/4” cylinder. For the most effective standard installations, the Installation Data on pages 4 through 7 should be used. These dimensions allow,for the different requirements of internal and external seals as well as reciprocating, static and rotary applications.
For non-standard applications the following table may be used as a guide. “Gland Depth” which equals the depth of the groove plus the radial clearance, determines the amount of “squeeze” on the 0-ring for effective sealing.
The most effective and reliable sealing is generally provided with the diametral clearance shown in the chart on page 4. When greater clearances occur, however, the graph below indicates conditions where 0-ring seals may be used — depending on the fluid pressure and 0-ring hardness,
It conditions fall to the right of the curve, extrusion of the 0-ring into the clearance gap will occur, greatly reducing the life of the seal. As an example, with .004 diametral clearance and 2500 psi pressure, extrusion will occur with a 70 durometer 0-ring, but no extrusion will occur with an 80 durometer 0-ring.
The effective range of service is considerably greater when BACK-O’s are used.
While Parco manufactures 0-RING COMPOUNDS 0-rings in more than a dozen different elastomers, the following six elastomers account for more than 95% of all 0-ring production. Elastomer groups are listed by popularity.
PURPOSE OF BROCHURE designed as a quick and easy reference for proper selection of an 0-ring to match your particular needs. The brochure contains information on 0-ring size and installation data, 0-ring compounds and their compatibility with fluids, and a chart of popular military/aerospace specifications.
YOUR PARCO DISTRIBUTOR bZ equipped to provide you with full service. He is prepared to assist you in the selection of the proper seal, but that’s only the beginning. He stocks a full range of Parco sealing products and can provide a local safety stock for your specific needs. In addition, most of our distributors are equipped to provide special packaging or product identification tailored to your needs.
Depend on him. He is a local independent businessman who cares very much about helping you with your complete sealing needs.
Parco seahng products he carries include:
excellent resistance to most petroleum products and fuels and can be compounded over a temperature range of 65 to + 300°F. Nitrile compounds have, excellent reistance to compression set or cold flow, tear and abrasi6n. They do not possess good resistance to ozone. sunlight or weathering.
4200-70 Parco’s most popular, general purpose nitrile compound.
2291-70 FDA nitrile for use in contact with foods.
4456-70 Excellent compatibility with stress-sensitive plastics.
FLUOROCARBON (VlTONtm or FLUORELtm) — Many designers are switching from Nitrile to Fluorocarbons due to the superior combination of compression set resistance, high temperature properties and broad chemical resistance. These compounds can be used from -20 to + 400°F with brief intermittent exposureto +600°F.
9009-75 Parco’s most popular, general purpose fluoroelastomer compound. SILICONE — Silicones possess excellent resistance to temperature extremes. Special silicone compounds are capable of either -175°F flexibility or heat resistance to + 600°F, Generally used in static seals due to their poor tear and abrasion resistance, silicone compounds are often used for sealing medical products, electrical apparatus or for continuous service in dry air up to 400°F.
1235-70 Most popular general purpose silicone with temperature range from -80 to +400° F. FLUOROSILICONE — Combines the good high and low temperature properties of silicone, but with much better resistance to a variety of fluids. Fluorosilicones are commonly used in aircraft fuel systems. 1903.70 Our most popular fluorosilicone with temperature or range from -80 to ÷350°F. 1933-70
ETHYLENE PROPYLENE (EPR, EPDM) — Excellent general purpose temperature range (-65 to + 300°F) elastomer with superior resistance to wateC, steam, alcohols, engine coolants, sunlight and weathering. It has excellent resistance to Skydrol and other types of hydraulic fluids. Not recommended for use with petroleum oils or fuels. 5601-70 Our most popular “EPDM”; also conforms to FDA requirements except for milk and edible oils.
NEOPRENE (CHLOROPRENE) — Has the unique combination of resistance to weathering as well as resistance to petroleum lubricants over a temperature range from -65 to + 300°F, Neoprene also has good resistance to flexing and tear. Commonly used for refrigerant seals.
3110-70 Most popular general purpose (-40 to + 225°F) neoprene, conforms to FDA requirements except for milk and edible oils.
FLUID COMPATABILITY otmpo that are suitable for use in various fluids. When more than one compound is shown they are in the order of decreasing suitability. It is often necessary to make a compromise choice when several types of fluids and/or applications will be encountered. The temperature range, elastomer type and general characteristics of each compound in the table are included in the descriptive paragraphs. The table lists only 70 durometer compounds, but equivalent compounds of other hardnesses are also available, The two digits following the hyphen indicate the approximate hardness of Parco compounds.