Bell & Gossett Rolairtrol Air Separator

The Bell & Gossett Rolairtrol is a patented air separator with significant advantages. The Rolairtrol is capable of removing the air that commonly causes problems in commercial hot and chilled water systems. The Rolairtrol provides air free flow, improving efficiency and performance of the HVAC system.

It has a 3-to-1 body diameter, to nozzle diameter ratio slows the fluid velocity to help entrained air come out of solution, while its tangential inlet and outlet nozzles induces centrifugal fluid flow. This centrifugal flow creates a low-pressure vortex in the center of the tank where entrained air can come out of solution and float to the top of the tank where it can easily be removed through an air vent or connection to an expansion tank.

All Rolairtrol models are designed, constructed, inspected, and stamped per Section VIII, Division 1 of the ASME code for 125 psi (862 kPa) maximum working pressure and 350°F (177°C) maximum working temperature. Higher pressures and temperatures are available upon request. Models are available in sizes 2″ through 36″ and are available with NPT (2″ through 3” only), flange, or groove end connections.

Benefits of Rolairtrol

Below are the benefits of Rolairtrol:

• Every aspect of the Rolairtrol design maximizes air separation and simplifies installation and maintenance. The air separation efficiency of the Rolairtrol is significantly higher than any other commercial air separator on the market.
• It removes entrained air and suspended sediment to protect the system against damage and to provide better heat transfer. It also reduces energy costs and eliminates system noise.
• It creates low pressure vortex in center of tank and lowers pressure drop through the tank to control centrifugal flow pattern.
• The Rolairtrol provides maximum air separation efficiency due to a combination of centrifugal force and velocity reduction. The Rolairtrol’s tangential design creates a whirlpool inside the vessel. This vortex action sends heavier, air-free water to the outer portion of the vessel shell while forcing the separated air into the center where it is drawn to the air collector tube. The tangential design has been proven to have greater air separation efficiency when compared to less effective, straight flow air separators.
• It has an Exclusive B&G Design. It has an air collector tube is provided to efficiently gather and centralize the separated air. The separated air is easily directed upwards through the tube and vented in air elimination systems or returned to the compression tank in air control systems.
• Exclusive B&G Design – Unlike the upper, horizontal strainer location in competitive air separators, the Rolairtrol’s lower, vertical strainer does not interfere with the vortex action necessary for proper air removal.
• In addition to that, the Rolairtrol’s strainer is accessible from the bottom of the unit, reducing floor space while simplifying maintenance and clean out of accumulated system debris.
• According to the ASHRAE 90.1, there is a provision in the form of a clause on building energy transport systems. It states that “energy should be transported by the most efficient means possible and distributing systems should be selected to complement other system parameters such as control strategies, storage capabilities, conversion, and utilization efficiencies.” In such cases, an air bound system is an inefficient energy transfer system. When the B&G Rolaitrol removes entrained air from a commercial HVAC system, it allows the pumps and valves to operate and transport energy more efficiently.
• Each Rolairtrol size efficiently separate air from a system using a pump with the same size connection. If a 6" B&G end suction pump is sized to move 700 GPM at 27' TDH through a 6" pipe header, the Rolairtrol will separate 55% of the air on each pass while other units will only separate 22% (or less) of the air on each pass.
• The Rolairtrol is also available with or without a 304 stainless steel strainer to help break the fluid surface tension and remove suspended solids from your system fluid. Contaminants such as air and suspended sediment can lead to diminished heat transfer, higher energy costs, damage to your system components, and increased system noise. By removing them you can lower the cost to operate your system, extend the life of your components, and provide better comfort to your building occupants.

How the Rolairtrol Works

In order to evaluate air management of a specific application a better understanding of how temperature and pressure affect the solubility of air in water is required. Air is a mixture of gases, approximately 80% nitrogen, 20% oxygen and trace amounts of others. Within a short time after the initial fill, the air in a properly operating closed system begins to lose its oxygen content through oxidation. Unless fresh water, with its 2% air is added, the gas remaining becomes nitrogen, an inert gas. The chart in Figure 2 illustrates the effects of pressure and temperature on the solubility of air in water. With the air out of solution, the air separator will isolate the air and move it to the air vent for air elimination, or send it to the compression tank for air management.

The principles governing the design of air separators are simple. One is by reducing the water velocity to ½ ft. /sec or less. Water will not carry along free air bubbles at that velocity. Stokes’ Law explains the separation process. Separation occurs when the buoyancy of the air particle exceeds the gravitational force and the friction force created by the system water. The Rolairtrol enhances the separation process by using centrifugal force to separate the air from the water rather than relying on gravity alone. Gravity is the only variable that can be improved in the formula. The centrifugal force created by the Rolairtrol pushes the heavier water toward the shell and the lighter air toward the air collector where it will move to the top of the Rolairtrol. This is the most efficient method of separating air in large commercial HVAC applications.

Why to trust Bell & Gossett Rolairtrol Air separator brand?

For over 90 years Bell & Gossett has brought you the most reliable and innovative products for hydronic, HVAC and plumbing systems. From pumps and heat exchangers, to air management systems and valves, Bell & Gossett knows what you need to get the job done right the first time and provide lasting value. Your local Bell & Gossett representative is an experienced professional with a wealth of technical expertise. Because they know systems from design to operation, they can give you the advice and support you need to successfully install, operate and maintain your hydronic systems.

The famous Bell & Gossett Little Red Schoolhouse opened in 1954 as a dedicated facility for training. Over the past 55 years we have trained more than 50,000 engineers, contractors and installers in the proper design, installation and maintenance of HVAC systems. We can help you understand the complexities of air management from a system perspective. Our fully equipped learning center is the only facility of its kind, and Bell & Gossett is proud to set the standard for professional education and HVAC system innovations. The competitive units are more expensive than the Rolairtrol, and the Rolairtrol costs less to operate and has better air removal performance. This is the best advantage that you can get when you opt for Bell & Gossett Rolairtrol Air separator.

The Rolairtrol uses a combination of low velocity and centrifugal action to help separate entrained air from the water. The difference in density of the two fluids forces the air toward the low velocity area in the center, where it rises to the top of the vessel and accumulates in the air collector. The air then passes through an air vent and is vented to the atmosphere or it is directed to a compression tank.