Rotary valves handle two jobs at once — metering material flow and maintaining a pressure seal between two zones of a pneumatic conveying system — so most faults show up as either a flow problem or a pressure loss. Here are the six most common, what to check first, and when it's a wear-item replacement versus a bigger issue.
1. Pressure Loss Across the Valve
Pressure loss is usually rotor-to-housing clearance opening up from wear, rather than a sudden failure. Clearance increases gradually with abrasive material and duty cycle, so a small, steady rise in leakage across the valve over months is expected wear, not necessarily a fault — but track it, since excessive clearance eventually affects conveying system performance.
2. Rotor Not Turning or Turning Intermittently
Check drive coupling condition and motor operation first. If the drive is confirmed functional, material bridging above the valve inlet or a jammed object between rotor and housing is the next most likely cause — do not attempt to clear a jam without isolating the drive first.
3. Shaft Seal Leakage
Seal leakage is a wear-item issue in the vast majority of cases, accelerated by abrasive material contacting the seal face. Confirm leakage is actually at the shaft seal and not material escaping through excessive rotor clearance, since the fix differs — seal replacement versus rotor/housing service.
4. Unusual Noise or Vibration During Operation
New noise or vibration typically indicates bearing wear, a rotor blade contacting the housing due to excessive clearance or misalignment, or an object caught inside the valve. Isolate and inspect before continuing operation — running a valve with rotor contact accelerates damage quickly.
5. Material Flow Inconsistency
If metered flow rate has drifted from what it was at commissioning without a speed change, check for rotor pocket wear or buildup restricting pocket volume, particularly with sticky or fine materials that can pack into rotor pockets over time.
6. Motor Overload or Drive Trips
Drive trips are often caused by an obstruction or bridging above the valve increasing torque demand suddenly, rather than a motor fault itself. If trips are recurring rather than a one-off, check for a developing mechanical issue (bearing wear, rotor contact) that's steadily increasing load.
When to Call for Support
The checks above cover the diagnostics a technician can perform without disassembly. Escalate when: rotor clearance needs measurement and comparison against wear-tolerance limits, seal or bearing replacement is needed, or your bore size is non-standard and the replacement part needs to be sourced against your specific configuration.
Spare Parts and Ongoing Support
Rotor blades or vanes, shaft seals, and bearings are the parts most likely to need periodic replacement — wear rate depends heavily on material abrasiveness, so what's normal for one application may not be for another. ENZAC provides spare parts supply and scheduled service and maintenance for the rotary valves it supplies, and separately for third-party valves of the same type. For abrasive applications, it's worth establishing what wear rate is expected for your specific material as part of your maintenance planning, so a technician can distinguish normal wear from a developing issue during inspection.
Review the full Rotary Valve equipment page for bore sizing and rotor configuration detail.
Ready to talk about your rotary valve?
If a fault on your rotary valve isn't resolving with these checks, or you need spare parts sourced for your specific bore size and rotor configuration, contact ENZAC with your equipment details and we'll get you the right part.