1. Field of application and purpose
This practical guide defines the mandatory procedures for technical maintenance of industrial compressed air systems according to the requirements of standards ISO 8573 (air quality), ISO 50001 (energy management) and current DSTU regulations. The instruction is intended for mechanics, maintenance technicians and reliability engineers of Ukrainian industry.
Regular execution of this schedule prevents premature wear of pneumatic actuators, prevents production equipment stoppages due to moisture and oil ingress, and reduces the energy consumption of the compressor station. The procedure covers servicing of refrigerant and adsorption dryers, replacement of filter elements of main filters, and conducting ultrasonic leak detection of compressed air under working pressure.
2. Precautionary Measures and Safety
DANGER WARNING: The compressed air system is under high pressure (operating range 6-10 bar). Unauthorized pressure release may result in serious injuries or hose and valve detachment.
LOCKOUT/TOUCH-UP (LOTO) REQUIREMENTS: Before starting any mechanical work, perform full energy source isolation:PPE (Personal Protective Equipment): Mandatory use of safety goggles (EN 166), protective gloves against mechanical injuries and low temperatures (when working with refrigerant), safety footwear with steel toe cap (EN ISO 20345) and protective ear muffs (EN 352-1) during purging and operation of compressor equipment.
- Fully close the shut-off valve supplying air from the receiver/compressor to the maintenance area.
- Lock the valve in the closed position using the LOTO overhead lock.
- Open the manual residual pressure release valve (Drain Valve) and ensure with the pressure gauge that the pressure has dropped to 0.0 bar.
- Turn off the electrical power supply of the dryer and the filter station at the main control panel, and install a warning sign "DO NOT SWITCH ON! People are working".
3. Required Tools and Materials
| Назва інструмента / матеріалу | Technical specification | Quantity |
|---|---|---|
| Ultrasonic Flow Meter | Frequency range 35-42 kHz (with parabolic antenna and headphones) | 1 pc. |
| Digital Manometer | Class accuracy 0.5, range 0-16 bar | 1 pc. |
| Torque wrench | Range 10-50 Nm and 40-200 Nm | Kit |
| Combined Key Set | Sizes 10 mm – 32 mm | 1 set |
| Hex key set (Imbus) | Sizes 3 mm – 12 mm | 1 set |
| Digital Multimeter | True RMS, voltage measurement up to 600 V AC/DC, resistance | 1 pc. |
| Infrared pyrometer | Range -30°C to +500°C | 1 pc. |
| Wet-bulb temperature analyzer | Portable compressed air hygrometer (-80°C...+20°C Td) | 1 pc. |
| Variable filter elements | According to the micrometer rating of the housing (0.1 µm, 0.01 µm, graphite) | According to the design specification |
| Sealing rings (O-rings) | NBR / Viton (depending on the presence of lubricant in the line) | According to the filter kit |
| Technical wipes | Woven industrial paper towels | 1 package |
| Anaerobic adhesive / PTFE tape | For high-pressure threaded connections | 1 pc. |
4. Pre-Maintenance Inspection Checklist
| Element | Method of inspection | Acceptance / Rejection Criteria | Notes |
|---|---|---|---|
| Inlet pressure and temperature | Visual inspection of pressure gauges and thermometers at the system inlet | Pressure: 7.0 - 8.5 bar, Air Temperature: not higher than +35°C (refrigerant dryer) | Temperature overrun reduces the dryer's performance by 20-30% |
| Condensate removal operation | Manual check of the TEST button or acoustic control of operation | Clear open/close cycle without continuous air leakage | Blocked condensate drain leaves water in the pipeline |
| Condition of main pressure gauges | Comparison of pressure drop (Delta P) before and after filters | Pressure drop across the filter does not exceed 0.35 bar (35 kPa) | More than 0.5 bar means critical contamination of the element |
| Visual inspection of pipelines | Corrosion traces, mechanical damages and bulges of flexible hoses | Absence of corrosion on metal pipes, absence of cracks on hoses | Pay attention to the corner connections and consumer connection points |
| Refrigerant Parameters | Condensation and boiling pressure check on freon circuit manometers | Conformance to table values for refrigerant R134a / R404a | Significant deviation indicates a refrigerant leak or dirty condenser |
5. Step-by-step Servicing Procedure
Step 1: Service and cleaning of the refrigerant / adsorption dryer
- Дія: Виконати процедуру LOTO для електричної та пневматичної частини осушувача. Перекрити вхідний та вихідний запірні вентилі осушувача, відкрити байпасну лінію (якщо передбачено технологічною схемою) або повністю зупинити компресорну станцію.
- Злити залишковий конденсат через ручний дренажний кран.
- Remove the housing panels of the dryer to access the heat exchanger and condenser.
- Дія: Очистити повітряний конденсатор холодильного контуру.
- Видалити пил та бруд з ребер теплообмінника за допомогою продування стисненим повітрям під низьким тиском (не вище 2 бар) у напрямку, зворотному до руху повітря, або за допомогою промислового пилососа.
- Typical error: Do not use high-pressure water jet or aggressive chemical solvents, as this causes deformation of aluminum blades and corrosion.
- Action: Check the operation of the electronic or float condensate trap.
- Remove the condensate drain valve, clean the mesh filter (sludge trap) with ultrasonic cleaning or wash in a cleaning solution.
- Check the electrical part of the valve using a multimeter (the resistance of the solenoid coil should correspond to the passport value, typically 1.2 - 2.4 kΩ).
- Дія: Запустити систему в роботу та перевірити точку роси під тиском (Pressure Dew Point).
- Відкрити вхідний клапан, подати живлення. Точка роси має стабілізуватися в межах +3°C ... +5°C для рефрижераторних осушувачів та -40°C для адсорбційних.
- Visual indication: Green indicator 'Ready / Normal Operation' on the control panel.
Step 2: Replacement of main filter elements (pre-filter, fine filter, carbon filter)
- Action: Perform a complete pressure release in the filter housing using the built-in relief or drain valve.
- Warning: It is prohibited to unscrew the filter bowl under pressure. This will result in thread failure and ejection of the bowl with high kinetic energy.
- Дія: Демонтувати нижню чашу корпусу фільтра за допомогою спеціального ключа або вручну (залежно від типорозміру).
- Вийняти використаний фільтрувальний елемент. Оглянути внутрішню поверхню чаші на наявність масляних відкладень, корозії чи металевої стружки.
- Rinse the filter cup with a neutral cleaning agent, thoroughly dry with a lint-free cloth.
- Дія: Встановити новий змінний елемент.
- Змочити ущільнювальні кільця елемента чистою водою або технічним вазеліном (заборонино використовувати агресивні мастила, що руйнують гуму).
- Securely fix the new element in the mounting position inside the filter head.
- Дія: Зібрати вузол та затягнути чашу.
- Замінити ущільнювальне кільце чаші фільтра на нове з комплекту постачання.
- Затягнути чашу вручну до упору, після чого підтягнути ключем на кут не більше 15-30 градусів (згідно з інструкцією виробника корпусу). Не перетягувати різьбу.
- Visual indication of correct installation: even gap between the bowl and the filter head around the entire perimeter.
Step 3: Audit and Detection of Compressed Air Leaks
- Дія: Підготувати ультразвуковий течешукач.
- Увімкнути прилад, встановити частоту на рівні 38 кГц (стандартна частота турбулентного витоку повітря через отвір під тиском). Відрегулювати чутливість навушників.
- Дія: Провести сканування всієї пневматичної мережі підприємства.
- Послідовно обійти магістральні трубопроводи, розподільні колектори, з'єднання швидкороз'ємних муфт (quick couplings), регулятори тиску (FRL блоки), пневмоциліндри та золотникові розподільники.
- Mount the sensor at a 45-degree angle to the surface under test at a distance of 100-300 mm.
- Typical error: Scanning while production equipment is turned off leads to false positive results due to acoustic reflections; the audit should be conducted during the company's normal technological load.
- Дія: Локалізувати та позначити місця витоків.
- При фіксації звукового сигналу в навушниках та спрацьовуванні світлової шкали приладу, нанести на підозріле з'єднання мильний розчин або спеціальний течешукач у спреї для остаточного підтвердження.
- Mark the location of the leak with a tag or a water-resistant marker indicating the ID point and the flow rate (if calculated by the device).
- Action: Eliminate leaks.
- Tighten threaded connections with a torque wrench or replace worn sealing elements, pneumatic hoses (polyurethane/polyamide) and collet-type fittings.
6. Post-Maintenance Verification Checklist
| Test / Check | Expected result | Actual Result | Status (Passed / Not Passed) |
|---|---|---|---|
| Sealing of filter and dryer connections | No air leaks detected using a soap test at working pressure 8 bar | [ ] Pass [ ] Fail | |
| Dew point of compressed air | Stable indicators: +3°C ... +3°C (refrigerant) or -40°C (adsorption) | [ ] Pass [ ] Fail | |
| Pressure drop across filters (Delta P) | Less than 0.25 bar at each filtration stage | [ ] Pass [ ] Fail | |
| Operation of the automatic condensate drain | Regular condensate discharge cycle without pressure drop in the main line | [ ] Pass [ ] Fail | |
| Sound pressure level in the compressor | Reduction of background noise from leaks after defect elimination (audit) | [ ] Pass [ ] Fail |
7. Troubleshooting Guide
| Symptom | Likely cause | Correction action |
|---|---|---|
| Formation of water (condensate) in end-users of air | 1. Failure of the refrigerant dryer. 2. Clogging of the condensate drain. 3. Exceeding of the flow rate. | 1. Check the operation of the refrigeration circuit compressor. 2. Clean the condensate drain. 3. Check the network load, clean the condenser. |
| Fast contamination of new main filters | 1. Separator damage of the compressor. 2. Corrosion inside the compressed air receiver. 3. High air temperature on the inlet line (>45°C). | 1. Replace the oil separator of the screw compressor. 2. Carry out inspection and drain the receiver. 3. Install an additional aftercooler. |
| Frequent actuation of the condensate drain solenoid | 1. Membrane sticking or timer failure. 2. Too short time interval between operations (Timer ON/OFF incorrectly set). | 1. Disassemble the valve, clean or replace the solenoid repair kit. 2. Reset the condensate drain timer parameters. |
| High pressure drop on the filter element (>0.5 bar) | 1. Clogging of the filter layer with microparticles of dust or remnants of compressor oil. 2. Operation of the element beyond the established service life. | 1. Immediately perform replacement of the variable filter element. 2. Check the filtration quality at the line inlet. |
8. Recommended Technical Maintenance Schedule
| Task | Periodicity | Estimated duration | Personnel Qualification |
|---|---|---|---|
| Drain condensate, visual inspection of pressure gauges | Daily | 10 minutes | Operator / Technician (Level 1) |
| Moisture Point Check and Desiccant Operation | Weekly | 15 minutes | Technician (Level 1) |
| Cleaning the dryer condenser of dust | Monthly | 30 minutes | Technician (Level 2) |
| Replacement of variable elements of main filters | Every 4000 hours or once a year | 1.5 years | MRO Specialist (Level 2) |
| Full ultrasonic inspection of coils throughout the plant | Every 6 months | 4-8 hours | Reliability Engineer (Level 3) |
| Comprehensive check of the refrigerant circuit of the dryer | Every year | 2 years | Certified Refrigeration Equipment Engineer |
9. Spare Parts Catalogue and UNITEC-D Categories
| Description of the part | Typical specification | Category UNITEC |
|---|---|---|
| Variable element of the main filter (Grade A - dust) | Rating 1 µm, mesh frame made of stainless steel | Air Filtration |
| Variable fine cleaning element (Grade B - oil) | Rating 0.01 µm, coalescent material | Air Filtration |
| Variable carbon element (Grade C - odour/vapours) | Activated carbon in granules, oil residue <0.003 mg/m³ | Air Filtration |
| Electronic condensate drain with level sensor | 230V AC, working pressure up to 16 bar, connection G 1/2" | Drainage systems and condensate removal units |
| Drain solenoid valve repair kit | NBR Membrane, piston, spring | Pneumatic Actuators and Fittings |
| Condensation point sensor under pressure | 4-20 mA output, range -80°C...+20°C | KVPS and automation |
| Quick-connect connections and fittings (Push-in) | Nickel-plated brass, ferrule clamp for tubes 6-12 mm | Pneumatic fittings |
For selecting original spare parts and equivalents of European brands for your compressor station, visit our Electronic Catalog UNITEC-D.
10. References and Regulatory Basis
- ISO 8573-1: Air Filtration. Part 1: Frosting of Contaminants and Cleanliness Classes.
- ISO 50001: Energy Management Systems. Requirements and guidance for use.
- DSSTU EN 1012-1: Compressors and vacuum pumps. Safety requirements. Part 1: Air compressors.
- OEM technical documentation of compressor equipment manufacturers (Atlas Copco, Kaeser, CompAir, Boge).
