Custom Spiral Conveyor

We are known for providing reliable, custom designed Spiral Systems. One way that we maintain our reputation is through our ability to provide an extensive options menu. Our custom spirals range in capacity from 200 to over 20,000 lb/hour, and are designed to provide the ideal environment for cooling, freezing, proofing or drying the specified product. The following is a list of some options currently available. Of course we are always continuing to improve our versatility and quality, so we regularly incorporate new, reliable technologies.

For a list of related terms, see our Glossary

Feature Options
Belting Material
Refrigeration Freon Condensing
Air or Water Cooled
Factory Ammonia
Defrost Air
Hot Gas
Insulated Enclosure Materials & Size
Spiral Configuration Components



We typically utilize Stainless Steel, Nylon and Acetal Plastic belts in our custom spirals. Many other plastics are available for special applications: Polyethylene (PE), Polypropylene (PP), Nylon, X-ray Detectable Acetal. Each material offers particular benefits for Spiral conveyors, and we work with our customers to find the best choice. This decision depends upon the temperature, tension, and what is known as release—the tendency for product to stick to the belt material. Integrated or hybrid belts, which harness the strengths of both Stainless Steel and Plastic, are also available.


Belts are engineered with several factors in mind. They must meet demands in throughput capacity, tension, and extreme temperatures as well as product shape, texture and weight, to name a few. Belt width typically varies between 10 and 54 inches and a variety of side guards ensure that even the slickest products will not slide off of the conveyor. Another important consideration in belt selection is the turn ratio. This is the ratio of the tightest possible inside turn radius to the belt width (TR=IR/W). A 12” wide belt with a 2.0 turn ratio is capable of making a 24” radius turn; the drum diameter would then be at least 48”, while the belt helix diameter would be 72″ or slightly larger.


Stainless Steel belts are offered with a wide range of mesh types and weaves, which are identified by a series of letters and numbers [xx-yy-zz]. These diverse offerings allow us to accommodate products of nearly any size, and to control the weight of the belt and the airflow to the product. Tighter mesh overlays will reduce airflow and increase the belt weight per foot. The symbols represent three different features: the number of loops per 12” of belt width [xx], the number of connectors per 12” of belt length [yy], and finally the wire gauge [zz]. The nomeclature “30-12-16” indicates a mesh overlay with 30 loops for every 12” of belth width, 12 connectors for every 12” of belt length and 16 gauge wire. Additional symbols may be used to represent manufacturer-specific offerings.

Product Spacing

It is essential that the minimum product spacing be maintained when loading the spiral.  Due to the belt design, the belt collapses against the drum as it enters the spiral.  This collapse effectively decreases the distance between rows of product on the spiral.  As a rule of thumb, there must be a gap between each row that is half of the product length.  Failure to maintain this standard can cause the product to push together resulting in damage to both the product and the spiral.



Given the nearly limitless variety of food and other products that we handle, we work to provide our clients with a refrigeration package that is efficient and easy to maintain. Making the right selection involves more than Btu/hr calculations.

Condensing Units

HFC (Freon) systems are widely available, and HFCs have been gradually replacing HCFCs and CFCs, which are harmful to the ozone. R-404a and R-507 are the most used low temp HFC refrigerants. Ammonia (R-717) provides a small boost in efficiency when compared with Freon, and is most commonly used as part of a facility-wide ammonia system. Ammonia is also a less expensive refrigerant, but exposure is more hazardous and requires a well planned design. If our customer has not invested in a large ammonia system supplying multiple pieces of equipment, then most users find it easier to deal with individual Freon systems.

Aircooled vs Evaporative. We offer both air-cooled and evaporative (water-cooled) condensing units, each with its own set of benefits. Air-cooled units are known for their low initial investment, simplicity and general savings in maintenance. Evaporative units are cooled with water and require less electricity, and they have a smaller footprint, but water quality must be adequately maintained.

Factory Ammonia

Our Spirals can be connected to a new or existing facility Ammonia system. This is sure to provide a boost in efficiency and factory integration. Ammonia can be supplied as an independent small unit, but that is less common.


Typically we focus on mechanical (vapor compression) refrigeration because it is significantly cheaper to operate (see article). Cryogenic systems can have a lower initial cost vs. installing a condensing unit, but the spiral system will last for many years and it makes more economic sense to choose a conventional refrigerant. A mechanically cooled spiral can be cheaper after a couple years than even a straight running liquid nitrogen tunnel. However, when a product requires quick surface-freezing, the extreme low temperatures of Liquid Nitrogen (LN) and Carbon Dioxide (CO2) may be the only solution.


Frost buildup is the result of moisture in the air collecting and freezing onto a sufficiently cold surface. You may notice it coating your car in the morning or your grass in the yard. However, when it collects on refrigeration coils, the system can lose upwards of 30% of the design airflow.

Air Defrost

Air defrost is the practice of shutting down the refrigeration package, while leaving the fans on and the doors open. This requires no additional controls or devices, and can be surprisingly fast given its simplicity, but it requires that the ambient temperature surrounding the enclosure is above freezing.

Water Defrost

Water defrost is also a very simple defrost method. Basically a drip pan is installed above the evaporator coil and used to cascade hot water over the iced coil. A drain pan catches the water below the coil and it runs out through a heated drain pipe.

Hot Gas Defrost

The Hot Gas defrost system requires a shorter down-time and is independent from the ambient environment. The system operates by drawing hot gas from the compressor and sending it through the coils, melting the frost buildup. It has a minimal load on the electrical infrastructure.

Electrical Defrost

Electricity is supplied to wires wrapped around the coil fins, generating heat and rapidly melting away excess ice. This can be done either in sections or it can be performed on the entire coil during shutdown periods. It is easily installed and controlled.

Glycol Defrost

Glycol is a food grade antifreeze and is a commonly used liquid desiccant for a Continuous Defrost system. It is applied directly to the coil, as a cascade that gathers moisture as flows over the coil surface, preventing frost build up. Excess water is then removed from the glycol run-off, and the Glycol is recirculated over the coil.

Scheduled vs Sequential vs Continuous

Scheduled Defrost: Many producers elect to shut down the spiral system for defrost and cleaning because that is the simplest defrost plan. During the shutdown air, hot gas, water or electrical defrost methods may be used. Twenty minutes is about the minimum time required for a scheduled defrost.

We also enable our clients to defrost refrigeration coils without interrupting production with a Sequential or Continuous defrost design. For high humidity environments or long run times sequential or continuous defrost methods are used.

In a Sequential Defrost, the apparatus is programmed to defrost one deactivated evaporator coil at a time, and air flow is rerouted accordingly. There must be at least two evaporator coils. The coils are equipped with surplus capacity to compensate for the deactivated section. Hot gas or electrical defrost are the only feasible methods for a sequential defrost.

In a continuous defrost system, the entire coil remains active while being defrosted.  In fact, frost never is able to form on the coil.  Glycol is the most common continuous defrost method.

Insulated Enclosure

Each of our insulated enclosures is designed to custom-fit the space available within the production facility and to allow minimal air infiltration. Doors come equipped with thermometers, lighting and frame heaters and can be constructed in various sizes and configurations.

Materials & Size

Interior surfaces of the ‘box’ are usually constructed with food-grade stainless steel, while the exterior surface can be customized for function, appearance, and cost, utilizing either stainless or galvanized steel.  Cam-locks ensure ease of assembly and disassembly, while reinforced panels provide structural integrity to combat rotational and vibrational forces.  Panel thickness is also variable to suit an insulation need.  Insulation is foamed-in-place polyurethane.  Four inch thick panels provide R-32 insulation.  Standard walk-in freezer doors are 34″ wide, 72″ tall, but can be adjusted per customer demand.

Spiral Configuration

Component Configuration

Process Engineering is also one of the few manufacturers that will reconfigure each component of the Spiral for the best-fit into the production facility. Fans, Coils and drive motors can all be moved in order to adjust length, width, and height of the enclosure.

Spiral Configuration

Several options are available for product loading and unloading from the Spiral. They are diagrammed below. Tangential Infeeds are also available for more delicate products.


Spirals can be placed in series to make double tower (double drum) spiral systems.  Our customers are also given the choice between an “up” and a “down” spiral.  In an “up” configuration, the product enters at the base of the helix and travels upward.  The change in height is dictated by the number of tiers and the tier pitch.  For example, if the product enters the spiral 30″ off of the ground and proceeds to travel up 10 tiers with a 5″ pitch, the product will exit the spiral at 80″ from the ground.  A “down” spiral transfers product from top to bottom.

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