Elimination of compressed air pressure drops: Systematic diagnosis of leaks and optimization of the network

1. Description of the problem and scope of application

Pressure drop in compressed air systems is a critical issue that directly affects operational efficiency, energy consumption, and equipment life. This manual is intended for technical specialists, reliability engineers and heads of maintenance departments at production enterprises in Ukraine. It provides a systematic approach to diagnosing and eliminating the root causes of pressure drops.

Symptoms considered:

• Insufficient pressure at the point of consumption (pneumatic tools, drives, technological processes).
• Decrease in productivity or complete stoppage of pneumatic equipment.
• Frequent loading/unloading cycles of the compressor or its constant operation at maximum capacity.
• Increased electricity consumption by the compressor station.
• Unusual vibration or noise in the piping system.

Hardware affected by the issue:

• Compressors (screw, piston, centrifugal)
• Air dryers (refrigerator, adsorption)
• Filtration systems
• Receivers
• Main and distribution pipelines
• Pneumatic tools and executive mechanisms
• Valves, fittings, hoses and quick disconnects

Severity Classification:

• Critical: A drop in pressure that leads to a complete shutdown of a production line or critical equipment. Requires immediate intervention.
• Significant: Pressure drop that reduces equipment performance, product quality, or significantly increases energy consumption. Requires prompt removal.
• Minor: Small but constant pressure drops, leading to unnecessary energy costs and accelerated equipment wear. Requires scheduled diagnostics.

Standards governing quality and efficiency:

• DSTU EN 1012-1:2014 Compressors and vacuum pumps. Security requirements. Part 1: Compressors.
• ISO 11011:2013 Compressed air. Assessment of energy efficiency.
• ISO 8573-1 Compressed air. Part 1: Contaminants and purity classes.

2. Precautions

DANGER: Working with compressed air systems involves risks including high pressure, electrical current, moving parts and hot surfaces. Failure to follow safety instructions can result in serious injury or death.

• Personal protective equipment (PPE): Mandatory use of protective glasses, protective gloves, headphones to protect against compressor noise and durable work clothes.
• Lockout/Tagout (LOTO): Prior to any diagnostic or repair work requiring access to internal components or piping, MUST apply Lockout/Tagout procedures in accordance with internal company instructions and DSTU EN 1037:2006 Machinery Safety. Unexpected startup prevention. Make sure the compressor is de-energized and all sources of compressed air are shut off.
• Знегерметизація системи: УВАГА: Стиснене повітря є накопичувачем значної енергії. Перед розбиранням будь-яких компонентів системи або від'єднанням трубопроводів ПОВНІСТЮ ВИПУСТІТЬ ТИСК до атмосферного через відповідні дренажні клапани. Перевірте показники всіх манометрів, щоб переконатися у відсутності тиску.
• Hot surfaces: After stopping the compressor and dehumidifier, some components may remain hot. Wait for them to cool before touching.
• Working with electricity: Only qualified electricians should carry out diagnostics of the compressor's electrical systems, observing all electrical safety standards.

3. Necessary diagnostic tools

Effective diagnosis of pressure drops requires a set of specialized tools that allow accurate measurement and localization of problems.

4. Initial evaluation checklist

Before starting detailed diagnostics, perform the following initial assessment to get a general idea of the state of the system and possible directions for troubleshooting.

5. Systematic flow of diagnostics

This diagnostic flow will help you sequentially identify the root cause of the pressure drop, starting with broad symptoms and narrowing down the search.

1. Symptom: General pressure drop throughout the system (at the receiver and consumption points).
   1. Check the production capacity of the compressor:
      1. Check the inlet air filter:
         • If the pressure drop across the filter > 0.2 bar: The filter is clogged. Probable cause: Suction limitation.
         • Actions: Replace the filter.
      2. Check the operation of the intake valve:
         • If the valve does not open completely or has mechanical damage: Probable cause: Reduced intake air volume.
         • Actions: Repair or replace the valve.
      3. Check the condition of the compression element:
         • If there is visible wear on the rotors (screw) or piston rings (piston): Probable cause: Reduced compression efficiency due to internal leaks.
         • Actions: Repair or replace the compression element.
   2. Analyze air demand:
      1. Measure total air consumption with a flow meter:
         • If total consumption > rated compressor capacity: Probable cause: Excessive air demand.
         • Actions: Optimize consumption, eliminate leaks (see below), install an additional compressor or a higher performance compressor.
      2. Measure air consumption during off hours (base demand):
         • If base demand > 10% of total demand: Probable cause: Significant leaks in the system.
         • Actions: Go to ultrasonic leak diagnostics.
2. Symptom: Normal pressure at the receiver, but a drop in pressure at remote points of consumption.
   1. Diagnostics of the air distribution network:
      1. Ultrasonic inspection:
         • Use an ultrasonic leak detector to inspect the entire network of pipelines, fittings, valves, and quick-disconnect connections.
         • If multiple leaks with a level > 0.1 dB are detected: Probable cause: Significant leaks in the system.
         • Actions: Locate and fix leaks (see "Fixing Leaks").
      2. Checking the filters and dryers after the receiver:
         • If the pressure drop on the main filters or dryer > 0.1 bar: Probable cause: Clogging of the filters or restriction of the flow in the dryer.
         • Actions: Replace the filter elements or service the dehumidifier.
      3. Inspection of pipelines for the presence of restrictions:
         • Visually inspect the pipelines for dents, corrosion, blockages, reduction of the internal diameter.
         • If flow restriction is detected: Probable cause: Incorrect pipe diameter, clogging, corrosion.
         • Actions: Replace the damaged sections, check the diameter of the pipelines according to the flow and length.
      4. Checking pressure relief valves:
         • Measure the pressure before and after the pressure relief valve at the point of consumption.
         • If the pressure after the valve is significantly lower than the set one and the pressure before the valve is normal: Probable cause: Malfunction of the pressure reducing valve (diaphragm wear, clogging, defective spring).
         • Actions: Adjust, repair, or replace the pressure relief valve.
3. Symptom: Reduced quality of compressed air (high dew point, presence of condensate/oil).
   1. Diagnostics of dryer and filters:
      1. Dew point measurement:
         • If the dew point after the dryer is higher than normal (+3°C for refrigeration, -40°C for adsorption): Probable cause: Dehumidifier malfunction (freon leak, adsorbent clogging, valve malfunction).
         • Actions: Carry out technical maintenance of the dryer, replace the adsorbent, eliminate freon leaks.
      2. Checking oil and coalescing filters:
         • If there is oil or condensation after the filters: Probable cause: Clogging of filter elements or failure of automatic drains.
         • Actions: Replace the filter elements, check and clean the drain valves.

6. Matrix of malfunctions and causes

This matrix provides a summary of common symptoms, their likely causes, diagnostic methods, and expected outcomes.

7. Root cause analysis for each malfunction

A deep understanding of root causes is key to preventing repeated failures.

7.1. Compressed air leaks

Why they occur: Leaks are the most common cause of pressure drop and energy loss. They arise due to:

• Mechanical wear: Wear of seals, O-rings, hoses, quick-disconnect connections.
• Incorrect installation: Insufficient tightening of fittings, lack of Teflon tape or sealant on threaded connections.
• Vibration: Weakening of connections due to constant vibration of equipment and pipelines.
• Corrosion: Destruction of metal pipelines and fittings due to the presence of condensate or aggressive substances.
• Damage: Mechanical damage to pipelines, hoses, collectors.

How to confirm: The most effective method is the use of an ultrasonic leak detector, which allows you to detect even small leaks, invisible to the eye, by registering the high-frequency noise generated by the exhaust air. A thermal imaging camera can also visualize the cooling of the leak area.

Potential Damage: Leakage is a direct waste of precious energy generated by the compressor. Even a small hole with a diameter of 3 mm at a pressure of 7 bar can cost a company up to 500-700 euros per year in the form of lost energy. They lead to the constant operation of the compressor, its premature wear, increased maintenance costs and reduced pressure at consumption points.

7.2. Malfunction of reduction valves

Why they occur: Reducing valves are designed to maintain a stable output pressure. Their malfunctions can be caused by:

• Spring Wear: Loss of spring stiffness resulting in unstable or low pressure.
• Clogging: Particles of dirt, rust or condensation can enter the valve and interfere with its proper operation, blocking the movement of the diaphragm or stem.
• Membrane damage: The membrane can crack or wear, losing its ability to regulate pressure.
• Corrosion: Internal valve components can corrode, preventing valve movement.

How to confirm: Pressure measurements before and after the valve using calibrated pressure gauges. Comparison of the actual pressure with the set one. Disassembly and visual inspection of internal components.

Potential damage: Unstable or low pressure after the reduction valve leads to incorrect operation of pneumatic equipment, reduction of product quality and possible stops of technological processes.

7.3. Clogging of filters

Why they arise: Filters are the first line of defense against contamination (dust, oil, condensate). Their clogging is a natural process, but with untimely replacement it leads to problems:

• Exceeding the service life: Using filter elements after the end of the recommended service life.
• Contaminated air intake: Operation of the compressor in a dusty environment without proper pre-cleaning.
• Dryer malfunction: If the dryer is not working efficiently, the increased amount of condensate can clog the main filters more quickly.

How to confirm: Measure the pressure drop across the filter using a differential manometer. Visual inspection of the filter element (discoloration, visible contamination).

Potential Damage: A clogged filter creates significant resistance to air flow, resulting in a pressure drop after the filter, reducing system performance and increasing the load on the compressor, increasing its energy consumption and wear.

7.4. Excessive demand for air

Why they occur: The demand for compressed air can exceed the capacity of the compressor due to:

• Increasing the number of consumers: Adding new pneumatic equipment without assessing the impact on the compressor station.
• Inefficient use: Valves left open, hoses supplying air to nowhere.
• Hidden Leaks: A significant number of undetected leaks that create constant but unproductive demand.
• Decreased compressor performance: Actual compressor performance may have decreased due to worn or clogged filters, creating an "over demand" situation even without an increase in consumption.

How to confirm: Measurement of total air consumption with a flow meter and comparison with the nominal performance of the compressor. Analysis of compressor operation schedules (continuous operation under load).

Potential damage: The compressor operates in a constant load mode, which leads to its overheating, increased energy consumption, accelerated wear and frequent failures. The system cannot maintain stable pressure, which affects production processes.

8. Step-by-step elimination procedures

Effective troubleshooting requires accurate procedures.

8.1. Elimination of compressed air leaks

Tools: Ultrasonic leak detector, wrench set, Teflon tape, thread sealant, new seals/fittings.

1. Isolation and depressurization:
   • Critically IMPORTANT: Isolate the leaking area by closing the inlet and outlet valves. COMPLETELY RELEASE THE PRESSURE from the isolated area to atmospheric. Check the absence of pressure with a pressure gauge. (DANGER: Accumulated Energy!)
   • Apply the LOTO procedures to the appropriate areas.
2. Location and Marking: Use an ultrasonic leak detector to pinpoint leak locations. Mark each location of the leak (for example, with a tag or a special marker) for later remediation.
3. Determining the type of leak: Assess whether the leak is due to a damaged hose, a loose threaded connection, a worn seal, or a faulty valve.
4. Performance of repairs:
   • Hose/Pipelines: Replace damaged sections with new ones that comply with the DSTU EN ISO 14743 standard (for pneumatic systems).
   • Threaded joints: Disassemble the joint, clean the threads, apply new teflon tape (3-5 turns clockwise) or anaerobic thread sealant. Tighten the connection to the recommended torque (for example, for DN25 threaded connection 30-40 Nm).
   • Fittings/Quick Disconnects: Replace damaged or worn fittings and quick disconnects. Check the presence and condition of the sealing rings.
   • Valves: If the leak is due to a faulty valve, it must be repaired (replace seals, membranes) or replaced with a new one.
5. Verification: After the repair is complete, slowly increase the pressure in the system. Re-test the repaired areas with an ultrasonic leak detector to ensure there are no leaks.

8.2. Replacement of filter elements

Tools: Set of keys, new filter element, clean cloth.

1. Isolation and depressurization: Isolate the area where the filter is installed. COMPLETELY RELEASE THE PRESSURE from the filter housing. Apply LOTO.
2. Dismantling: Carefully unscrew the filter housing, following the manufacturer's instructions.
3. Replace element: Remove the old filter element. Clean the inside of the filter housing from dirt and condensation. Install the new filter element making sure it is oriented correctly (if there is a flow direction). Check the condition of the housing seals.
4. Installation: Tighten the filter housing by hand, then tighten with a wrench to the recommended torque. Do not drag.
5. Verification: Slowly pressurize the system. Check for leaks around the filter housing. Check the pressure drop reading on the new element.

8.3. Adjustment and repair of reduction valves

Tools: Calibrated pressure gauge, set of keys, repair kit (if necessary).

1. Isolation and depressurization: Isolate the area where the valve is installed. COMPLETELY RELEASE THE PRESSURE. Apply LOTO.
2. Adjustment Check: If the valve is adjustable, try to adjust it to the desired pressure by watching the pressure gauge after the valve.
3. Disassembly and inspection: If the adjustment does not help, disassemble the valve. Take it apart, carefully inspect the membrane, spring, internal channels for wear, damage or blockage.
4. Repair/Replacement: Clean the components. Replace damaged parts (diaphragm, spring) using the original repair kit. If the valve is severely worn or damaged, consider a complete valve replacement.
5. Verification: Assemble and install the valve. Slowly increase the pressure. Check the output pressure setting and stability with a calibrated pressure gauge.

9. Precautions

Prevention is more effective than eliminating the consequences. Implementation of regular preventive measures will significantly reduce the risk of pressure drop and increase the reliability of the system.

10. Spare parts and components

Availability of quality spare parts is critical to prompt troubleshooting and minimize downtime.

To order quality spare parts and components for compressed air systems that meet industry standards CE and UkrSEPRO, please visit the UNITEC-D e-catalog: www.unitecd.com/e-catalog/

11. Links

• DSTU EN 1012-1:2014 Compressors and vacuum pumps. Security requirements. Part 1: Compressors.
• DSTU EN 1037:2006 Machine safety. Unexpected startup prevention.
• DSTU EN ISO 14743:2018 Pneumatic systems. Hoses and hose connections.
• ISO 11011:2013 Compressed air. Assessment of energy efficiency.
• ISO 8573-1:2010 Compressed air. Part 1: Contaminants and purity classes.
• Manuals for operation and maintenance of compressors and pneumatic equipment from manufacturers.
• Internal instructions of the enterprise on labor protection and maintenance.
• UNITEC-D: Guide to the optimization and maintenance of compressor stations, edition 2026.