Maintenance Guides 1 min read

Support and Maintenance of Aircraft Training Equipment (FRL): Instruction for Technical Personnel

Technical analysis: Air preparation unit (FRL) maintenance checklist: filter elements, regulator diaphragms, lubricator

Support and Maintenance of Aircraft Training Equipment (FRL): Instruction for Technical Personnel

1. Application Place and Purpose

This instruction provides practical recommendations for the maintenance and servicing of an air preparation unit (FRL), which is used in industrial air distribution systems. The main components of the unit include an air filter, pressure regulator, and lubricator. Servicing of FRL is performed to ensure stable and safe operation of industrial equipment, to shut off air consumption, and to prevent component wear. This instruction complies with the requirements of DSTU, EN, and ISO, as well as with the CE and UkrSEPRO standards.

2. Precautionary Measures

Turn off the power and air supply before starting work.
Use personal protective equipment (gloves, safety goggles, mask).
Install a mechanical lockout and a "Do Not Start" sign before accessing the air preparation unit.
Do not perform work at the workstation without appropriate personal protective equipment.

3. Required Tools and Materials

Tool Specification Quantity
Star key Range 10–30 Nm 1 pc.
Multimeter Pressure measurement mode (0–10 bar), temperature measurement (0–100 °C) 1 piece
Laser for Parallelism Measurement Range 0–1000 mm, accuracy ±0.01 mm 1 pc.
Air consumption measurement stand Max. 100 l/min 1 pc.
Measuring micrometer Range 0–25 mm 1 pc.
Lubricant for lubricator Special for air systems, ISO 1000 1 bin

4. Before Maintenance: List of Checks

Item Check Acceptance/Rejection Criterion Notes
1 Power Off and Air Flow Shutdown Confirmed block and subscription "Do not include" Use the locking device and sign
2 Pressure absence check in the system Pressure ≤ 0.1 bar Use the pressure gauge
3 Check for the presence of personal protective equipment All tools are present and compliant Including gloves and goggles
4 Air Filter Condition Check No peeling or contamination Use visual inspection
5 Pressure Regulator Check No leaks or wear Use the pressure gauge
6 Lubricator Check No leaks or absence of oiling Use visual inspection

5. Step by step: service procedure

  1. Power Off and Air Flow Shutdown
    Disconnect power and air flow to the installation. Install a lockout device and a "Do Not Operate" sign.
    Error: Performing work without power disconnection may result in injuries.
  2. Pressure and Temperature Measurement
    Use a pressure gauge and thermometer to measure the pressure and temperature in the system. The pressure must be ≤ 0.1 bar, and the temperature must not exceed 40 °C.
    Error: Pressure measurement at high values may cause leaks or explosion.
  3. Air Filter Removal
    Remove the filter mounting bolts (use a star wrench 10–30 Nm) and remove the filter. Check the filter condition for contamination, flaking or damage.
    Error: Failure to check the filter may result in air leakage.
  4. Pressure Regulator Removal
    Remove the pressure regulator mounting bolts (use a star wrench 10–30 Nm) and remove the regulator. Check for leaks, wear or membrane delamination.
    Error: Incorrect use of the wrench may cause damage to the regulator.
  5. Removal of lubricator
    Remove the mounting bolts of the lubricator (use a star wrench 10–30 Nm) and remove the lubricator. Check for leaks or absence of lubricant.
    Error: Absence of lubricator check may lead to wear of the air preparation unit.
  6. Air Filter Replacement
    Install the new air filter, ensuring proper installation. Use a star wrench 10–30 Nm to secure the filter.
    Error: Incorrect installation of the filter may cause air leakage.
  7. Pressure Regulator Replacement
    Install the new pressure regulator, ensuring proper installation. Use a star wrench 10–30 Nm to secure the regulator.
    Error: Incorrect installation of the regulator may cause air leakage.
  8. Lubricator Replacement
    Install the new lubricator, ensuring proper installation. Use a star wrench 10–30 Nm to secure the lubricator.
    Error: Incorrect installation of the lubricator may lead to wear of the air preparation unit.
  9. Return to operational use
    Turn on power and air flow. Check the pressure and temperature in the system. Measure the output pressure of the unit, it should be 0.5–0.7 bar.
    Error: Absence of pressure check may lead to air leakage.

6. Inspection After Maintenance

Test Expected result Actual Result Pass/Fail
System pressure ≤ 0.1 bar
Output pressure of the unit 0.5–0.7 bar
No leaks No leaks
Air filter Installed and operating
Pressure Regulator Installed and operating
Lubricator Installed and operating

7. Problem Correction Table

Symptom Causes Actions
Air leakage Worn filter, leakage from regulator, leakage from lubricator Replace filter, regulator and lubricator
Insufficient pressure Dirty filter, worn regulator, insufficient lubricant content Clean the filter, replace the regulator, add lubricant
Component Wear Insufficient lubricant content, leakage from the lubricator Add grease, replace lubricator
Insufficient heating Lubricator coil, insufficient lubricant content Add grease, replace lubricator

8. Recommended Maintenance Schedule

Task Frequency Duration Skill Level
Filter Cleaning Weekly 15 min Initial
Filter Replacement Once a month 30 min Average
Pressure Check Weekly 10 min Initial
Replacement of the regulator Once every 6 months 45 min Experienced
Replacement of lubricator Once every 12 months 60 min Experienced

9. Reference to Spare Parts

Component description Typical specification Category UNITEC-D
Air filter ISO 1000, 10–15 bar Category F1
Pressure Regulator 0.5–0.7 bar Category R2
Lubricator ISO 1000, 10–15 bar Category L1
Lubricant for lubricator ISO 1000 Category OIL

Зверніться до нашого е-каталогу на https://www.unitecd.com/e-catalog/ для отримання запчастин та деталей, необхідних для підтримки вашої аероподготовчої установки.

10. References

  • DSTU 3047–96: Technical specifications for various industrial installations
  • EN 60068-1: Electronic Components Testing
  • ISO 8068: Pressure measuring instruments
  • CE: Compliance Standards for Industrial Equipment
  • UkrSEPRO: Safety Standards in the Industrial Sector

Related Articles

Maintenance Guides 1 min read

Maintenance of the air preparation unit (FRL): replacement of filter elements, diaphragms of the regulator and filling of the lubricator

Technical analysis: Air preparation unit (FRL) maintenance checklist: filter elements, regulator diaphragms, lubricator

Maintenance of the air preparation unit (FRL): replacement of filter elements, diaphragms of the regulator and filling of the lubricator

Scope & Purpose

This manual is intended for the maintenance of compressed air preparation units (FRL - Filter-Regulator-Lubricator) in industrial pneumatic systems. Covers the following operations:

  • Replacement of filter elements (coalescent and dust filters)
  • Inspection and replacement of pressure regulator diaphragms
  • Refueling and adjustment of the lubricator
  • Cleaning and checking the tightness of nodes

Maintenance is carried out in accordance with DSTU EN ISO 8573-1:2016 (purity of compressed air) and DSTU EN 983:2015 (safety requirements for pneumatic systems). The recommended frequency is every 2000 hours of operation or once every 6 months (depending on operating conditions).

Safety Precautions

ATTENTION! BEFORE STARTING WORK:

  • Turn off the power to the compressor and de-energize the pneumatic system. Perform the Lockout/Tagout procedure according to DSTU EN 1037:2015.
  • Relieve the residual pressure in the system. Open the drain valve until the air has completely stopped escaping (minimum 30 seconds). The pressure in the system should be 0 bar.
  • Use personal protective equipment (PPE): safety glasses (EN 166), gloves (EN 388), safety shoes (EN ISO 20345).
  • Do not allow grease to fall on the floor - use a tray to collect the used liquid.
  • Work in a well-ventilated area. Lubricant vapors can cause respiratory tract irritation.

Tools & Materials Required

Tool/Material Specification Quantity
Dynamometric key Range 5–50 Nm, accuracy class ±3% 1
The screwdriver is insulated PH2 slot, insulation up to 1000 V (EN 60900) 1
Horn key Size 17mm, 19mm, 22mm 1 set
Control manometer Range 0–10 bar, accuracy class ±0.5% 1
Vernier caliper Digital, range 0-150mm, accuracy ±0.02mm 1
Pneumatic leak detector Sensitivity 1×10-6 mbar·l/s 1
Lubricant for pneumatics ISO VG 32 or ISO VG 46 (according to DSTU ISO 3448:2015) such as Mobil DTE 24 500 ml
Filter element Coalescent filter, class 1 μm (according to ISO 8573-1) 1
Diaphragm regulator Nitrile rubber (NBR), diameter 40–60 mm (depending on the model) 1
Sealing gaskets Silicone or fluororubber (FKM), thickness 1.5 mm 2–4 pcs.
Lint-free rags For cleaning surfaces 5 pcs.
Spray for cleaning No residue like CRC Contact Cleaner 1 balloon

Pre-Maintenance Inspection Checklist

Item Verification Acceptance/rejection criteria Notes
1. Pressure in the system Check the pressure gauge at the FRL outlet The pressure should be 0 bar. If >0.5 bar – the system is not de-energized. Use a control manometer for verification.
2. State of the filter element Visual inspection and pressure drop check Pressure drop > 0.5 bar or visible contamination - replacement is mandatory. For coalescent filters - the presence of an oil film on the surface.
3. Airtightness of connections Checking with a leak detector or soap solution The presence of bubbles is a leak. 0 bubbles allowed in 10 seconds. Pay special attention to threaded connections and seals.
4. Operation of the pressure regulator Turn the adjusting screw by ±1 turn The pressure should change smoothly, without jumps. If jumps > 0.2 bar – the diaphragm is damaged. Check for cracks on the regulator housing.
5. Lubrication level in the lubricator The inspection is visual through the sight glass Level below 50% - refueling required. If the lubricant is dark/dirty, replace it. Use only the recommended type of lubricant.
6. Condition of the drain valve Manual opening/closing check The valve should open freely, without jamming. The presence of corrosion - replacement. Clean the valve from dirt before checking.
7. Electrical connections (if any) Inspection of insulation and fastening Insulation resistance > 1 MΩ (measure with a megohmmeter at 500 V). The presence of oxidation - clean. Only for FRL with electronic control.

Step-by-Step Procedure

1. Dismantling the filter element

  1. Remove the filter cover.
    • Unscrew the cover fastening bolts (tightening torque 12–15 Nm). Use a torque wrench.
    • Remove the cover carefully - there may be residual condensate inside.
    • Avoid dropping the lid - it may damage the seal.
  2. Pull out the filter element.
    • Pull the element vertically upwards. If stuck, gently shake from side to side.
    • Inspect the element for mechanical damage (cracks, deformations).
    • Do not use metal tools for extraction - it can damage the filter housing.
  3. Clean the filter housing.
    • Remove condensation and dirt from the housing with a lint-free cloth.
    • Wipe the sealing surface with a cleaning spray. Make sure there are no scratches or corrosion.
    • Check the condition of the sealing ring - if there are cracks or deformations, replace it.

2. Replacement of the diaphragm of the pressure regulator

  1. Dismantle the pressure regulator.
    • Unscrew the regulator from the FRL housing (tightening torque 20–25 Nm).
    • Remove the adjusting screw and spring. Place them in a clean tray.
    • Do not lose small parts (washers, seals).
  2. Pull out the diaphragm.
    • Remove the upper cover of the regulator (bolts 8–10 Nm).
    • Gently pull out the diaphragm. Check it for cracks, breaks or deformations.
    • Measure the thickness of the diaphragm with a caliper - it should be 1.0-1.2 mm. If less, replacement is mandatory.
  3. Install the new diaphragm.
    • Grease the new diaphragm with a thin layer of grease (ISO VG 32).
    • Place the diaphragm in place, making sure it is flush in the slot.
    • Tighten the top cover (torque 8–10 Nm).
    • Do not overtighten the bolts - it can damage the diaphragm.
  4. Assemble the regulator.
    • Install the spring and adjusting screw.
    • Attach the regulator to the FRL housing (torque 20–25 Nm).
    • Adjust pressure to 6 bar (or according to system requirements).

3. Refilling the lubricant

  1. Drain the used lubricant.
    • Place a tray under the oiler drain valve.
    • Open the valve and drain all the oil. Close the valve after draining.
    • Do not allow grease to fall on the floor - use a pallet.
  2. Clean the lubricator.
    • Fill the lubricator with cleaning spray and shake.
    • Drain the liquid through the drain valve.
    • Repeat the procedure until complete cleaning.
  3. Fill in fresh lubricant.
    • Fill the lubricant up to the level of 75% (by sight glass).
    • Use only the recommended lubricant (ISO VG 32/46).
    • Close the lubricator cover (torque 5–7 Nm).
  4. Adjust the oil flow.
    • Turn the oiler adjustment screw 1/4 turn clockwise (minimum flow).
    • Connect the system and check for oil at the outlet (visually or using a paper filter).
    • Gradually increase the flow until the optimal level is reached (usually 1 drop per 10 m³ of air).

4. Assembly and verification of FRL

  1. Install a new filter element.
    • Insert the element into the filter housing, ensuring the correct orientation (the arrow on the element should point down).
    • Install the filter cover and tighten the bolts (torque 12–15 Nm).
  2. Check for tightness.
    • Connect a control pressure gauge to the FRL outlet.
    • Apply compressed air at a pressure of 7 bar.
    • Apply a soapy solution to all connections. The presence of bubbles is a leak.
    • If there is a leak, tighten the connection or replace the seal.
  3. Adjust the pressure.
    • Set the outlet pressure 6±0.2 bar using the adjusting screw.
    • Check the stability of the pressure - fluctuations should not exceed ±0.1 bar.
  4. Check the operation of the lubricator.
    • Start the system and make sure that the lubricant reaches the outlet.
    • Adjust oil flow as needed.

Post-Maintenance Verification Checklist

Check Expected result Actual result Passport/No passport
Airtightness of all connections No leaks (0 bubbles in 10 s)
FRL outlet pressure 6±0.2 bar (or according to requirements)
Pressure stability Fluctuations ≤ ±0.1 bar
Operation of the lubricator Lubricant flows to the outlet (1 drop/10 m³)
Operation of the drain valve The valve opens/closes freely, without leaks
Pressure drop across the filter ≤ 0.3 bar (for a new element)
Absence of extraneous noises No whistling, knocking or vibration

Troubleshooting Guide

Symptom Probable cause Corrective action
Outlet pressure below normal
  • Damaged regulator diaphragm
  • Dirty filter element
  • Leakage in joints
  • Replace the diaphragm
  • Replace the filter element
  • Check for leaks and tighten the connections
Outlet pressure is higher than normal
  • Jamming of the adjusting screw
  • Damage to the regulator spring
  • Disassemble the regulator, clean and lubricate the screw
  • Replace the spring
Air leaks from the regulator
  • Damaged diaphragm seal
  • A crack in the regulator housing
  • Replace the seal
  • Replace the housing or the entire regulator
Grease does not reach the outlet
  • Contaminated lubricant dispenser
  • Low oil level
  • Clogging of the oil line
  • Clean the dispenser
  • Add oil
  • Clean the oil line
Increased pressure drop across the filter
  • Contaminated filter element
  • Incorrectly installed item
  • Replace the element
  • Check that the installation is correct
Extraneous noises (whistling, knocking)
  • Damage to the bearings of the lubricator
  • Vibration due to loose mounting
  • Replace the lubricant
  • Check and tighten fasteners

Recommended Maintenance Schedule

Task Periodicity Estimated completion time Qualification level
Pressure and tightness test Every month 15 minutes Technician
Cleaning the drain valve Every 3 months 20 minutes Technician
Replacement of the filter element Every 2000 hours or 6 months 45 minutes Qualified technician
Replacement of the regulator diaphragm Every 4000 hours or 12 months 60 minutes Qualified technician
Refilling/replacing the lubricant in the lubricator Every 2000 hours or 6 months 30 minutes Technician
Full FRL Maintenance Every 8000 hours or 24 months 2 hours Qualified technician

Spare Parts Reference

Part description Typical specification UNITEC-D category
Coalescent filter element Class 1 micron, polypropylene, diameter 40–60 mm FRL-FILTER-ELEMENT
Dust filter element Class 5 micron, polyester, diameter 40–60 mm FRL-DUST-FILTER
Pressure regulator diaphragm NBR, diameter 40–60 mm, thickness 1.0–1.2 mm FRL-REGULATOR-DIAPHRAGM
Sealing ring for the filter Silicone or FKM, diameter 50–70 mm FRL-SEAL-RING
Lubricant for pneumatics ISO VG 32 or ISO VG 46, 1 l FRL-LUBRICANT
Drain valve Automatic or manual, thread G1/4

Related Articles