SOP For Preventive Maintenance of AHU & Ventilation Units

SOP For preventive maintenance of AHU & ventilation units is described in this post which you can follow in the section of the General Industry SOP.

OBJECTIVE

The purpose of this SOP is to provide stepwise instructions for Preventive Maintenance of AHU & Ventilation units.

SCOPE

This procedure is applicable for Preventive Maintenance of AHU & Ventilation units.

RESPONSIBILITY

Technicians  

Engineers 

ACCOUNTABILITY

Head Engineering

PROCEDURE

Precaution

Disconnect the machine from electric supply mains.

Tag “Under preventive maintenance” board on it. While checking the direction of rotators of a motor one must remove the belts, so as to avoid damages to machine due to reverse rotation.

No tools & spanners should be left on the machine after carrying out preventive maintenance.

General assembly Frequency: Once in month ±7days

Switch ‘OFF’ the main supply and display the ‘UNDER PREVENTIVE MAINTENANCE’ board prominently on the front side of AHU.

Check all the nut & bolts of supply air filter plenum are properly fixed and tight.

Check that no gap between supply air filter frame and filter plenum, tighten up the bolts/replace the gasket if required.

Check manually all the duct joint of the supply and exhaust duct for air leakages & arrest them by tightening up the nut & bolts/or replace the gasket if required.

Check the door lock & door handle for any damage, replace or rectify it if found damaged

Check manually the door gasket for any air leakage if found replace the gasket.

Check if the nut & bolts / screw of HVAC & VU cabinet are properly fixed and tight.(If found loose, tighten it up by suitable tools or replace it, if required).

Check the air leakage from HVAC & VU cabinet; tighten up the nut/bolts if required.

Check the canvas connection of terminal branch / blower suction and discharge; replace it with a new one if found damaged.

Check the entire duct joint for Air leakage, arrest it by tightening up of nut bolts or replace the gasket if required.

Check the temperature of inlet / outlet of chilled water for its proper working.

Check the temperature of inlet / outlet of hot water for its proper working.

Check all the nuts and bolts of filters unit and tighten it up, if found loose and replace with new one, if it is found missing.

Check the air/dust leakage from filter unit and joint of if found, arrest it by tightening of nuts and bolts or replace the gaskets if required.

Check the canvas connection of blower suction/discharge side; if found damaged, replace it with a new one.

Electrical

Open the panel of the machine & clean it properly.

Tighten all the electrical connections, if found loose.

Clean the contacts of the contactor.

Check that the relay setting of the machine motor is at the rated maximum current of the motor.

Check the DOL reversible starter for proper reverse & forward direction of the motor, if not, rectify/replace it.

Dress all the cables / conduits in the panel & replace if required.

Switch ‘ON’ the main supply and check all sensors for its working.

Cooling Coil

Switch ‘OFF’ the main supply.

Open the doors of cooling coil section of the AHU.

Clean the surfaces of and cooling coil with the dry cloth.

Wash the inner surfaces of fins with the water.

Clean the drain of the AHU and inner surfaces of the AHU with the cloth.

Ensure that the water is not stagnant at the drain.

Note: Inform to production department before taking coil for cleaning

Motor

Ensure that the main power supply of the equipment is disconnected & all utilities are isolated.

Ensure that the machine is free of any dust on it.

Remove all the guards of the machine & remove the main motors.

Dismantle the motor.

Check the condition of the bearing & replace if required.

Check the winding insulation & if required same to be rectified.

Lubricate the bearings with AP-3 or its equivalent grease & assemble it on the shaft.

Reassemble the motor.

Blower

Remove the pulleys from its position.

Check the condition of the pulley / Key / Keyways & rectify / replace if required.

Check the condition of the belts & replace if required.

Check the condition of the bearings & replace if required.

Lubricate the bearings with AP-3 or its equivalent grease.

Fit the pulleys back to its position.

Fit the ‘V’ belts on the pulleys

Remove the ‘UNDER PREVENTIVE MAINTENANCE’.

Trial

Switch ON the main supply to the machine.

Check the operation of the machine & set if required.

Check the current drawn by the motors; it should not be more than the rated current.