Tuthill Solutions for Asphalt Applications

Tuthill Pump Group's Solutions for Asphalt Road Construction and Roofing Products

Fluid Engineering is proud to represent Tuthill Pump Group and its line of pumps which are ideally suited for the Asphalt Industry, which is itself divided into two principal markets, Road Construction Materials, and Asphalt Roofing Materials.

Asphalt Road Construction Materials
The road construction materials market for asphalt consists primarily of materials used in the construction of roads, streets, alleys, public sidewalks, guardrails, parkways and airports. More than 94% of the more than  two-million miles of streets and highways are paved with asphalt. Asphalt is a preferred material for the construction of roads and highways because asphalt roads are:

  • smooth,
  • cost-effective to construct and maintain,
  • exceptionally durable,
  • environmentally friendly, and
  • 100% recyclable.

Types of Asphalt
Two types of asphalts mixes are used in road construction, Hot Mix Asphalt ("HMA") and asphalt emulsion.

Hot mix asphalt consists of an aggregate component, which comprises 95% of the total weight of an asphalt pavement, and asphalt cement, which comprises the balance of the pavement. The aggregate component consists of crushed stone, gravel and sand. It is almost always locally available stone. The asphalt cement component is a black liquid that acts as the glue to hold the pavement together. It is a petroleum product generally obtained from the same refineries that produce gasoline and heating oil. It is one of the heaviest, most viscous parts of petroleum.

Asphalt emulsion is a combination of three basic ingredients, asphalt, water and an emulsifying agent. These ingredients are introduced into a colloid mill. The emulsifier keeps the asphalt droplets in a stable suspension. The finished product has a consistency ranging from that of milk to heavy cream. It can be used in cold processes for road construction and maintenance. The emulsion does not require a petroleum solvent to make it liquid, and in most cases, it can be used without additional heat. Both of these factors contribute to energy savings of emulsified versus hot mix asphalt. Additionally, asphalt emulsions offer greater flexibility in their applications. They are more environmentally friendly as there are little or no hydrocarbon emissions created with their use. 

Asphalt Roofing Materials
The asphalt roofing materials market consists of "establishments primarily engaged in manufacuring, from purchased materials, asphalt and other saturated felts in rolls or shingle form, either smooth or faced with grit, and in manufacturing roofing cements and coatings." Over 12.5 billion square feet of asphalt roofing materials are produced each year for use to roof 80% of the 5 million homes roofed in America each year.

Roofing shingles are manufactured with a base (also termed "mat" or "substrate") made of either organic-based or fiberglass-based materials. Organic-based mats are made of various cellulose fibers, such as recycled waste paper and wood fibers. Fiberglass-based mats are composed entirely of glass fibers of varing lengths and orientations. Regardless of base material used, the mat is the saturated with a specially-formulated asphalt-coating, followed by weather-resistant mineral granules.

There are four major types of asphalt roofing shingles: 

  • Strip Shingles are approximately three times as long as wide. The most common strip shingle is the "three tab" shingle.
  • Laminated Shingles contain more than one layer of tabs to create extra thickness. They are referred to as "three-dimensional" or "architectural" shingles. They are the favorite among builders, roofing contractors, and homebuyers.
  • Interlocking Shingles are individual shingles that are mechanically fastened to each other. They are used to provide greater wind resistance.
  • Large Format Shingles are generally rectangular or hexagonal in shape and do not utilize cutouts.

Another type of asphalt roofing material is Roll Roofing, available in three major types:

  • Saturated Felt is an asphalt-impregnated, organic-based felt used as an underlayment between roof decking and the roofing materials. It is produced in a variety of weights.
  • Specialty-Eaves Flashing is a self-adhering, polymer-modified bituminous sheet material. It is designed for special flashing applications along roof eaves and in other areas.
  • Mineral-Surfaced Roll Roofing is a rolled roofing material used as a primary roof covering, most frquently on small or secondary-use buildings. The tops surface of the roll is imbedded with mineral granules.

Pump Applications for Asphalt Services
Typical pump applications in the asphalt industry are for pumping liquid asphalt and for pumping the heat transfer oil required to handle hot-mix asphalt.

The challenges with pumping asphalt include  issues with housekeeping and product loss or waste associated with traditional packing, which leaks by design. The desire for leakage control has led to a growing interest in mechanical sealing options for asphalt pumps. Seconf, cold starts (starting pumps before all the solidified asphalt in the pump has been melted by heat transfer) lead to failureof packing, mechanical seals, and lead to potential rotor damage.

Tuthill Solutions
On asphalt services, Tuthill GlobalGear® pumps are available with jacketed brackets and covers. The Global Gear product line was designed for primary use with mechanical seals, rather than as a secondary application as with the Viking 34 series asphalt pump. The Global Gear pump has the widest range of upgraded packing and seal solutions in the industry. This allows Tuthill to offer the best solutions to the most demanding applications in the industry.

On filled asphalt applications, Tuthill offers its HD and GlobalGear® Series process pumps with hardened parts. These pumps feature slower operating speeds (at equal flow rates) relative to competitor products as well as the upgraded packing and seal solutions mentioned above.

The GlobalGear® answer to industry demands is with larger shaft sizes than equivalent size Viking pumps, which are better suited to handle high discharge pressures and spike without excessive deflection. Further, available seal vents to suction help prevent product buildup in front of the seal.It also reduces the shock of discharge pressure spikes. Finally, as mentioned before,  GlobalGear® pumps were designed specifically for use with mechanical seals.

Contact Fluid Engineering today at 1-800-841-9944 for assistance with your asphalt or other pump application needs!

Source:  "Asphalt: Road Construction and Roofing Product" by Keith Harris.

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