Transfer Pumps, also known as Drum Pumps or Stick Pumps, feed materials to the proportioner. No Diaphragm Pumps should be used. The Transfer Pumps should meet the following criteria:

• Positive displacement stick pumps work best with higher viscosity materials.
• 2:1 ratio required because of viscous materials.
• 100 psi air supplied to pump = 200 psi output pressure.
• Minimum ¾” moisture lock supply hose to proportioner.

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Transfer Pump Air Motor Operation

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Air Driven System

Air-driven systems are considered easy-to-use entry level machines for low-output applications, and can deliver up to 25 pounds of material per minute. Air machines are generally used for in-plant applications or as an entry-level machine for contractors.

The relatively low cost of air-driven machines makes them attractive, particularly to start-ups. However, business growth and expansion into new applications may soon necessitate the purchase of larger, higher output machines.

Because air-driven machines require an air compressor to operate, in-plant foam applications where large air compressors are available on-site make these machines an attractive and cost effective choice.

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Electric Driven System

Electric spray foam machines have become the most popular systems in the industry, and are considered mid-level production units, delivering between 20-30 pounds of material per minute. Due to the mid-range output of the electric machines, typical applications are residential construction and mid-sized industrial construction.

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Hydraulic Driven System

Hydraulic spray foam machines are high output units, delivering 30-50 pounds of material per minute. These machines are well suited for a range of applications, such as residential construction, larger commercial buildings, roofs, and oil & gas applications. These high output units allow operators to apply material faster and more efficiently than other options.

Another consideration is the life span of the various types of machines. The typical life span of electric foam spray machines can easily be 7 to 10+ years. Due to their robust design, hydraulic spray foam machines last a bit longer, 10 to 12+ years. Keep in mind that many factors contribute to the useful life of a piece of equipment, including usage rates, the application environment and preventive maintenance.

The larger pumps on the hydraulic sprayers cycle less frequently, so they need to be rebuilt less often - on average every one to two years. Conversely, pumps on air and electric machines may need to be rebuilt more often, based on the reduced output per stroke.

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Hydraulic Pump Operation

There are several different types of foam guns from a few different manufacturers, but for this explanation we are going to focus on the Graco Fusion AP. This is the most popular gun on the market. See reference links to other popular guns at the bottom of this section.

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Graco Fusion Air Purge

• Air operated
• Air purged(clean off)
• Multiple mixing chamber sizes
• Mix takes place in chamber
• Chamber size dictates system output
• Always have a spare gun and parts

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Fusion AP Parts Assembly

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Fusion Ap Operation

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Mixing Chamber Sizing

Remember that doubling flow rate significantly reduces ΔT. Enverge recommends using an AR4242 mixing chamber in most applications. This chamber size allows for excellent control with an optimal flow rate suitable for most scenarios. The round pattern allows for application in a wide variety of circumstances. For a faster flow rate on wider open substrates or deeper cavities, a 5252 chamber can be used.

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Link to Popular Spray Guns

Graco Spray Foam Guns

• Fusion AP
• Fusion CS
• Fusion MP
• GX-7 & GX-8
• P2
• GAP

PMC Spray Foam Guns

• AP-2
• PX-7
• AP-EX

Heated Hoses

• Designed to maintain heat from machine heaters to gun.
• Heats to set point on display.
• Uses thermocouple to maintain setting.
• “A” hose must be “moisture lock”.
• A, B, air and FTS Sensor wire.
• Butt connectors for electrical circuit.
• Must be insulated, no gaps in insulation.
• Protect with scuff jacket, duct tape.
• 50’ section most common.

Spray Hose Requirements

• Typical spray hose dimensions are 50 ft lengths with ½ inch or ⅜ inch diameter.
• Temperature Sensing Unit (TSU) is installed on the A-side and must be installed before the whip.
• Maximum hose length is dependent on Proportioner (see owners manual).
• Heated spray whips are required in colder conditions.

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Hose Volume

• Hydraulic pressure drops with hose length.
• The greater the hose length, the greater the pressure drop from the proportioner to the gun.
• In general, the pressure drop is 1 lb/in2 per 1 foot of hose length.
• Low pressure will result in under processing, poor cell structure and poor yield.