Technical Deep Dive: The Extreme Advantage of PERMA/flo Rotary Valves

Focus: XL/XT Series Rotary Valves (The specialized component the competition lacks)

Goal: Educate engineers on why the P-33 Chrome-Iron Alloy is superior to standard surface-hardened valves for abrasive service.

Introduction: When "Heavy Duty" Isn't Enough

In pneumatic conveying, the rotary valve is the heart of the system, acting as both a feeder and an airlock. For materials like cement, fly ash, and minerals, standard "heavy duty" valves suffer from rapid internal wear, leading to increased air leakage, reduced conveying efficiency, and costly unscheduled downtime. Delta Ducon designed the PERMA/flo XL and XT Extreme Rotary Valves specifically to surpass this industry limitation.

The Core Difference: Solid Alloy Durability

The critical differentiator of the PERMA/flo valve lies in its proprietary material construction, which guarantees longevity where other valves fail.

Feature	Standard Industry Valve	Delta Ducon PERMA/flo (XL/XT Series)
Wear Resistance	Often features surface hardening.	Rotor and inlet shoe are cast from a special P-33 Chrome-Iron Alloy.
Material Hardness	Typically uses softer base materials once the surface wears off.	Achieves a hardness of 500–600 Brinell (BHN).
Longevity	Surface hardening eventually wears off, exposing softer base metal.	P-33 is a solid alloy casting; the hardness runs through the entire component, meaning it does not wear off to expose softer metal.
Classification	Often classified as "Heavy Duty".	Classified as Severe Duty.

Maintaining the Seal: Precision and Adjustability

A tight rotor-to-seal shoe gap is essential for maximizing airlock efficiency and preventing cross-flow. The PERMA/flo design incorporates a unique feature that allows the rotor-to-shoe gap to be maintained even as wear occurs over time. This adjustment can be made quickly while the valve is still installed.

• Adjustment Capability: The unique design allows for the adjustment of the clearance between the rotor and the seal shoe.

• Maintenance Focus: This adjustability ensures the tightest possible seal is maintained throughout the entire life of the unit.

• Ease of Service: Adjusting and maintaining this critical clearance can be made while the valve is still in place.

Engineering Enhancements: XL vs. XT Series

The PERMA/flo family has evolved to optimize feeding efficiency:

• XL Series (14"–24"): This is the traditional design, applied as rotary feeders and airlocks. The 14", 18", and 24" models utilize a 9-pocket rotor.

• XT Series (6"–12"): Enhanced design introduced in 2003 with an increased throat size. This was achieved by increasing the rotor pockets from nine to ten. The larger inlet (up to 82% larger than the previous design) and wider shoe minimizes possible bridging while increasing pocket fill efficiency.

Model Size ("A")	Model Type	Capacity (Cu. Ft./Rev. @ 100% eff.)	Number of Rotor Pockets
6"	XT	0.20	10
8"	XT	0.375	10
14"	XL	1.60	9
24"	XL	6.00	9

📞 Secure Your Abrasive Service System

You can specify a rotary valve to simply feed product, or you can specify the PERMA/flo valve—a long-term investment that minimizes air leakage and eliminates the cost of frequent component replacement in severe duty applications.

Ready to move beyond surface-level hardening? Contact a Delta Ducon engineer to discuss how the PERMA/flo Extreme Rotary Valve can maximize the uptime and efficiency of your most abrasive conveying lines.