What is the material? How many pounds per hour do you want to process?

Properly drying plastic resin is essential to achieving high-quality molded parts, especially for hygroscopic materials such as nylon, PET, or polycarbonate. At IMS Company, we offer Dri-Air desiccant dryers engineered for efficiency, reliability, and precision.

One of the most common questions we hear is: How do I size the right dryer for my process?

1. Know Your Material and Throughput

Before you can select the correct dryer, you must answer two critical questions:

• What material are you drying?
• How many pounds per hour will you be processing?

Each plastic resin has its own recommended drying time and drying temperature. You can usually find these values in your material supplier’s technical datasheet. These specs are the foundation for dryer and hopper selection.

2. Dryer Sizing Rule of Thumb

A general guideline when selecting a dryer is: 1 CFM of process air per pound of material per hour. For example, if you are processing 25 pounds of nylon per hour, you’ll need a dryer capable of delivering 25 CFM of dry air.

3. Hopper Sizing Rule of Thumb

The drying hopper needs to be sized so that the material spends the full recommended drying time in the hopper before reaching the feed throat.

Hopper Size (lbs) = Drying Time (hrs) × Throughput (lbs/hr). Example: If your material requires 3 hours of drying time and you process 25 lbs/hr, then:

• Dryer blower: 25 CFM
• Drying hopper: 75 lbs

This ensures every pellet gets the full 3 hours of exposure to dry air, resulting in fully conditioned material when it reaches your screw.

4. Dryer Configurations

IMS/Dri-Air offers several desiccant dryer configurations to suit your floorplan and process needs:

• Machine-mounted dryers – Best for smaller applications with limited space.
• Floor-mounted dryers – Ideal when space is available and you need a dedicated drying station next to the press or extruder.
• Portable dryers – Designed for flexibility—move them from machine to machine as needed.

Refer to catalog page 686, (or your printed IMS catalog) for hopper sizes, mounting options, and blower capacities.

5. Why IMS/Dri-Air Dryers Save You Money

What makes IMS/Dri-Air dryers different? Efficiency.

Our dryers regenerate the desiccant beds using dry process air, not ambient air. This allows the heaters to operate only when regeneration is necessary—not on a fixed timer. This is controlled by thermocouples embedded in the beds.

Benefits include:

• Shorter heater run-times
• Lower energy consumption
• Faster payback

Other systems use timers or ambient air, which wastes energy and leads to inconsistent results.

Additionally, bed switching is also based on temperature, not time. This approach eliminates dew point spikes and delivers stable drying performance, part after part.

6. Optional High-Temp Cooling

If you’re drying materials at or above 250°F, we recommend an after-hopper cooler. This ensures your material won’t be overheated before entering the machine and protects downstream components.

Final Thoughts

Proper dryer sizing is critical for material performance and processing consistency. IMS/Dri-Air desiccant dryers are engineered with energy savings, consistent drying, and operational flexibility in mind.

If you’re unsure which dryer suits your needs, contact our team—we’ll help size the perfect system for your material, throughput, and floor layout.