APPLICATIONS

Exclusions seals - wipers and scrapers, are used to prevent and control the ingression of contaminants into a wide range of equipment, especially hydraulic and pneumatic cylinders/rams, plus many types of pumps and values. Typically, specialized wipers and scrapers are used to control aggressive contaminants, such as abrasives, slurries, ice, dust, and materials that form a strong adhesive bond on the surface of a rod, plunger, piston, or in a bore, cylinder or sleeve. These include the contaminants frequently encountered in steel and aluminum production, mining (above and below ground), forestry and agriculture, refuse and recycling, aviation and transportation, and many more:

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An Introduction to Exclusion Seals.

Hydrowype seals including rod wipers, scrapers and shavers are well suited for use in the presence of high heat, extreme cold, and significant contaminants ranging from large chips, crystals and conglomerates, to fine particles and dust down to the sub-5-10 micron size range.

The uniquely coiled construction, heat-treat process and precision machining operations yield a seal that will maintain close rod contact throughout its lifespan. In most designs, a precisely calculated gap in the circumference of the seal allows for expansion and contraction where rod diameter varies. It also allows the seal to maintain the intended preload to effect the scraping action while the seal gradually wears throughout a typically long lifespan.

Installed in the “outboard” position of the gland/end cap of a cylinder, the seal removes dirt, mud, ice and other foreign matter from rods and shafts before such contaminants reach packing, seals, bearings or fluids. The wiper/scraper protects the rod or shaft from scoring and abrasion that cause damage to seals and packing.

All Hydrowype parts are precision-turned for concentricity and roundness. This provides for a superior cleanliness and sharpness of scraping surfaces relative to rod geometry.

In many cases, for the construction of exclusion seals, metals offer superior performance compared to elastomers for heavy-duty applications due to the absence of vulnerabilities resulting from aging, embrittlement and compression-set. In such environments and conditions, a metal seal may be expected to substantially out-perform and out-last an elastomeric seal of similar design. Metal seals are light-weight because of their very small cross-section, and are produced with almost zero waste from almost 100% recycled material. Used metal seals are 100% recyclable.

A metal-to-metal fit allows for close contact between rod and seal thus maximizing wiping/scraping potential. Metal has other beneficial attributes such as an ability to maintain a constant modulus of elasticity over time, making for conformity to rod irregularities that may develop through time and operating cycles.

In the presence of high pressures and temperatures that in other materials are likely to induce hardening, embrittlement and compression-set, metal will maintain its desired performance characteristics.

The designs of Hydrowype rod scrapers have their origins in the AN (Army-Navy) metal wiper specification (AN6231, May 1944), since superseded (MS28776, Nov 1972), current Rev D, (June 1988). The MS28776 specification, in combination with the MS33675 gland specification, define a floating scraper housed within a groove that maintains an axial and radial clearance to permit free, unobstructed movement and reduces the potential for interference resulting from shock or sideloading. The housing specification is intended for use in several types of glands including machined counterbores in a conventional gland, thread-in and press-in installation cartridge's (also know as cans or press-in housings) and installation adapters that permit the addition of the scraper within a pair of keeper and follower plates (rings). Most installations call for the use of a retaining ring installed into an out-board position ID groove in the housing counterbore, arranged such that assembly can be easily removed for inspection and cleaning. 

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