Installation and Troubleshooting Tips to Extend the Life of Pneumatic Valves

Most pneumatic valve manufacturers design their products to reach 20 million cycles or more under reasonable operating conditions and with proper maintenance. Some solenoid valves have been tested to achieve 100 million cycles in specific applications.

Factors that Influence Valve Longevity

Factors such as poor care, extreme temperatures and dirty or wet ambient conditions affect valve operation and service life.  Compressed air pressure, the presence of moisture or particulate matter, continuous high cycling or extended periods of stagnation can affect long-term valve performance, too.

Most valves are used until they become sluggish, stop cycling or develop a leak substantial enough to affect equipment performance. When those issues occur, repair or replacement is a reactive response. Today, however, there’s a growing trend in manufacturing to emphasize preventive maintenance.

Users are implementing regular maintenance schedules to evaluate valve “health” before it fails or presents warning signs. That can improve a manufacturer’s overall productivity by avoiding unplanned downtime and inefficiencies.

Maintenance and Performance Tips

Here are some tips for maximizing service life and troubleshooting valves that are sluggish, stuck or leaking.

Installation

  • Use compressed air to blow any debris from fittings and tubing before assembling the valve. Debris can get lodged inside critical sealing points, causing malfunctions and leakage.
  • Ensure exhaust ports are not restricted or blocked. Consider piping the exhausting air away from the valve when working in dirty or dusty environments.
  • Use exhaust port breathers to ensure adequate venting while blocking debris from entering the valve.
  • Keep the source air supply clean, filtered and free of moisture and debris as required by system devices. When necessary, use a factory-recommended airline lubrication.
  • In heavy industrial applications, install the valve in a vented enclosure or cover valve to protect it from damage caused by falling objects and workers.

Troubleshooting

  • Review manufacturer specifications and operate the valve within those limits. Exceeding specifications can lead to malfunctions or premature failure.
  • Set and maintain upstream air supply pressure to an adequate level to function reliably in your application.  Typically, a valve operating at a lower pressure will have a longer service life than one operating at a higher pressure.
  • Ensure there’s sufficient upstream air capacity for the valve and its downstream devices. Insufficient upstream volume can lead to pressure loss and valve malfunctions.
  • Maintain air preparation equipment to ensure only high-quality air enters the valve. That may also include draining or replacing filters, checking air gauges and refilling airline lubricators.
  • Clean or replace exhaust port mufflers before they can restrict a valve’s exhaust port flow capacity.
  • While many pneumatic valves do not require airline lubrication, other system components may need it.  In those cases, a 20- or 30-weight non-detergent petroleum-based oil is compatible with the Buna nitrile rubber seals used in most pneumatic valves.  Other lubricants can alter seals, resulting in reduced flow and premature failure.

Preventive Maintenance

Check for proper valve function and leakage regularly, especially at the beginning of a shift or if your equipment has been shut down for an extended time.  Valves should demonstrate a “crisp” shift to each position. Investigate any leakage at the exhaust or unused ports.

Inspect valves during downtime annually or semi-annually and review performance against manufacturer specifications. Look for changes in performance versus previous inspections. Assess flow capacity, response times, leakage and sluggishness. Determine whether it’s best to repair or replace a valve before it fails.

A Common Troubleshooting Mistake

Pneumatic directional control valves are most often used to operate double-acting air cylinders and air actuators.  Air leakage at the exhaust port may not be caused by the valve. It may be the result of a piston seal failure in the cylinder. To troubleshoot, carefully identify which of the airlines between the valve and cylinder is not pressurized. For example, if the piston rod is extended, the airline connected to the piston rod side of the cylinder is not pressurized.  Disconnect the tubing from the fitting and check for leakage from the cylinder.  If leaks are present, the cylinder is the source of the issue.

Durable Valves and Comprehensive Service from Humphrey Products

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