PMDS Self-Cleaning Rotary Valve

A mechanically self-cleaning rotary valve for applications where sticky or wet material can build-up in a conventional rotary valve or rotary feeder and disrupt feeding.  Two rotors – one for carrying the material and the second designed to sweep through the pockets on the first rotor – are timed together to effectively keep the rotor pockets clean and at full available capacity.  Using the same modular design principle as the PMV rotary valve, the PMDS is easy to maintain and rebuild if necessary.

PMDS Self Cleaning Rotary Valve cutaway 2

Common Applications

  • Coal mill feeding
  • Dryer feed
  • Feeding reactor vessels
  • Lignite or other higher rank coal
  • Activated carbon
  • Biosolids
  • Diatomaceous earth
  • Specialty chemicals
  • Pet coke
  • Sugar beet pulp
  • Hemp

Key Advantages

  • Eliminates the requirement to regularly stop production to clean out a conventional rotary valve in order to maintain process capacity; saves manpower and keeps the process continuously operating.
  • Minimizes process capacity fluctuations that can arise from material build-up in conventional rotary valves feeding a mill, process vessel, or reactor.
  • Can make lignite coal an economically viable fuel alternative as a key material handling challenge associated with it can be managed.
  • Modular design makes field repairs a reality; saving money and potentially reducing the investment in spares.
  • Compliant with NFPA 69 and 85 standards

Problems Solved

High inherent-moisture coal or coal with lots of surface moisture can be effectively handled without material build-up; useful in situations where raw coal must be stored outside or where incoming coal is carried in open-top trucks or rail cars.

For applications where metering or airlock functionality is needed at the inlet to the heated vessel with steam escapement, the PMDS can minimize complications from the steam mixing with the incoming material.

More positive cleaning action than air assist, vibration, or other add-on features to conventional rotary valves.

How It Works

A six pocket, closed-end, upper (product) rotor with special rounded pockets is matched to a 2-arm or 3-arm, open-frame sweeper rotor via an outboard gear set.  Rotation is timed so that each of the product-carrying upper rotor pockets is swept clean each rotation.

The key wear components – the rotor and the barrel sides – are manufactured of Tri-Braze abrasion-resistant steel for exceptional durability.

All major components in a PMDS are CNC-machined to thousandth-of-an-inch tolerances for precise fit and minimal rotor-to-barrel clearance.

Bolt-together, modular design makes component replacement possible – in place, in your workshop, or at Precision’s factory.

Internal surfaces of the barrel sides and wear plates can be chrome plated or ion-nitrided to increase surface hardness and reduce wear.

Rotor diameter is machined to a +/- 0.001” tolerance prior to final assembly for the operating temperature of your material – prevents lock-up due to thermal expansion.

Heavy-duty Dodge or Timken piloted flange bearings installed outboard of the housing to isolate heat.

Nord shaft-mounted gear-motor drive packages for clean, safe installations providing direct application of power with options for variable speeds and other functions.

PMDS Self Cleaning Rotary Valve

Options and Upgrades Available

304 or 316 stainless steel construction For corrosive applications
Zero Speed Sensors Detect and then alarm or notify that the valve is not operating
MSHA/OSHA-Compliant Shaft GuardsOperations and maintenance staff safety
TransitionsSlide-out/slide-in replacement of competitor’s rotary valves
Maintenance Gate Installation above the PMDS to facilitate repairs or adjustments in place
Modular design Makes “double-length” valves possible – increasing CFR without increasing height

Technical Specifications

Material TypesParticle sizes up to 2-3” for applications feeding raw coal to a mill.
Highly sticky materials including diatomaceous earth and lignite coal.
Moisture content up to 30-40%; preferably with minimal free liquid.
Compatible with product temperatures up to 700° F.
PMDS valves are not compatible USDA or FDA food-grade requirements
Power RequirementsDrive motors powered by
230/460V 3Ph 60Hz
575V 3Ph 60Hz
Other voltages and frequencies available

Zero speed sensors operate at control voltage.
VFD’s operate single-phase up to system voltage.

Let our applications specialists help you with your extreme-duty bulk material handling needs.