HIDCO/GM(E)IV/CS/NIT13/26-27

Supply and replacement of air filters for all Air Handling Units (AHU) and Cassette/Ceiling Handling Units (CHU) installed at the Convention Centre, comprising removal of existing choked/damaged filter media (pre-filters of washable/synthetic non-woven fabric, 10-micron average efficiency, and fine filters as applicable) from the filter section of each unit, and supply and fixing of new filters of matching size, micron rating and efficiency class (EU3/G3 for pre-filter and EU5/F5 for fine filter, or as existing), duly fitted in the filter frame/track with proper gasket sealing to prevent bypass air leakage. The work includes cleaning of filter housing, frame and mounting channel prior to fixing the new filter, checking of the filter clamping arrangement, and visual/manometric verification of pressure drop across the filter after installation. Old and discarded filters shall be removed from site and disposed of as per site instructions. The work shall be carried out AHU-wise and CHU-wise strictly as per the direction and schedule of the Engineer-in-Charge (EIC), without disrupting HVAC operation of unaffected areas. Rate shall be inclusive of all material, labour, tools, tackles, scaffolding/ladder, transportation, loading-unloading and disposal of waste, complete in all respects as directed.

Chemical cleaning and washing of the Air Handling Unit (AHU) cooling coil (fins) using an approved alkaline foaming coil cleaner to remove accumulated dust, grease, biological growth and scaling from the fin surface and coil tubes, thereby restoring heat transfer efficiency and airflow. The work comprises isolation and safe shutdown of the AHU, removal of access panels, protection of the surrounding motor, VFD, electricals and insulation from the cleaning chemical using polythene sheeting, application of the foaming cleaner uniformly over both faces of the coil, allowing the prescribed dwell/reaction time, followed by thorough rinsing with clean water using a low-pressure jet/spray without damaging the fins, and combing/straightening of any bent fins to restore fin spacing. The drain pan shall be cleaned of sludge and biological deposits, the drain trap and drain line checked for free flow, and the casing interior wiped clean and disinfected. After cleaning, the AHU shall be run and checked for leak-free operation, correct condensate drainage and improved delta-T across the coil. Rate to include all chemicals, consumables, protective sheeting, labour, tools, testing and making good, complete per AHU as required, all complete as directed by the Engineer-in-Charge.

Checking, correction and re-alignment of the AHU motor-blower drive assembly (pulley and coupling alignment) to eliminate belt wear, vibration, noise and bearing overload caused by misalignment. The work comprises isolation of the AHU, opening of the motor/blower access panel, visual inspection of motor and blower pulley faces, checking of parallel and angular alignment using a dial gauge/laser alignment tool or straight-edge and feeler gauge as applicable, and correction by loosening motor mounting bolts, repositioning/shimming the motor base with precision shims, and re-tightening to achieve correct pulley alignment within permissible tolerance. Belt tension shall be checked and adjusted to the manufacturer's recommended deflection, and motor base rails/slide rails greased for smooth future adjustment. Bearings of the motor and blower shall be checked for play/noise and lubricated as required. After alignment, the unit shall be run and checked for vibration levels, noise and current draw within rated limits. The work is applicable for all AHU capacities and drive configurations. Rate shall be inclusive of alignment tools/instruments, shims, consumables, lubricants, labour and testing, complete per AHU as required, all complete in all respects as directed by the Engineer-in-Charge.

Supply and replacement of standard section V-belt for the AHU blower drive, matching the size, section (A/B/C type as applicable) and length of the existing belt, to restore correct power transmission between motor and blower. The work comprises isolation and lock-out of the AHU, removal of the belt guard, slackening of the motor base/tensioner to relieve belt tension, removal of the old, worn, cracked or slipping belt, cleaning of pulley grooves of dust, grease and glazing, fixing of the new matching-specification V-belt (of reputed make, oil and heat resistant, anti-static as applicable), and setting of correct belt tension as per the manufacturer's recommended deflection using a tension gauge or standard deflection method. Where the drive uses matched multiple belts, all belts of the set shall be replaced together to ensure equal tension and load sharing. Pulley alignment shall be verified/corrected simultaneously if found disturbed. The belt guard shall be refitted securely after completion. The unit shall then be run and checked for smooth, vibration-free operation and correct blower RPM/airflow. Rate to include belt, labour, tools, consumables and testing, complete per set as required, all complete as directed by the Engineer-in-Charge.

Supply and replacement of V-belt Type B-84 (Section B, nominal length 84 inches, or equivalent metric designation) for the AHU blower drive at locations where the belt is reported missing, rendering the blower/AHU non-functional. The work comprises isolation and lock-out of the AHU, removal of the belt guard/access panel, inspection of pulley grooves and cleaning of dust, rust and foreign deposits, supply and fitting of the new Type B-84 V-belt of reputed make conforming to relevant IS/ISO standards for oil, heat and wear resistance, correct positioning on the motor and blower pulley grooves, and adjustment of the motor base/tensioner to achieve the manufacturer-recommended belt tension and deflection. Pulley alignment (parallel and angular) shall be checked and corrected if required prior to fitting the belt to prevent premature wear. The belt guard shall be refitted and secured after completion. The AHU shall then be started and run-tested to confirm smooth power transmission, correct blower speed, adequate airflow and absence of belt slip, squeal or excessive vibration. Rate shall be inclusive of belt, labour, tools, consumables, alignment check and testing, complete per each unit as required, all complete in all respects as directed by the Engineer-in-Charge.

Repair, servicing and restoration to automatic operation of motorised 2-way/3-way chilled water actuator control valves currently found stuck/faulty and running under manual (bypass) operation, to restore automatic temperature control of the AHU. The work comprises isolation of the chilled water line, dismantling of the actuator from the valve body, inspection and repair/replacement of internal gears, limit switches, spring-return mechanism, actuator coupling and wiring terminals as found defective, cleaning and lubrication of the valve stem and gland packing to prevent leakage, and re-assembly of the actuator onto the valve ensuring correct stroke and fail-safe position setting. Control wiring from the AHU/BMS controller to the actuator shall be checked, re-terminated and tested for correct open/close and modulating signal response. After repair, the valve shall be functionally tested through its full travel, flow balancing carried out to achieve the designed chilled water flow, and the supply air temperature verified against the set-point to confirm proper closed-loop control. Rate to include spares, labour, testing instruments, flow balancing and commissioning, complete per valve as required, all complete as directed by the Engineer-in-Charge.

Repair and re-commissioning of the Variable Frequency Drive (VFD) panel controlling the AHU blower motor, including supply of a new VFD card/power module where found burnt or defective, and transportation of the same to site. The work comprises isolation of the VFD panel, diagnosis of the fault (power module, control card, display unit, cooling fan, input/output terminals, etc.), removal of the defective card/component, supply and fitting of a compatible replacement card/module of matching make, rating and firmware version, re-wiring/re-termination of power and control cables, and re-configuration of drive parameters (motor rated current, voltage, frequency, acceleration/deceleration ramp, minimum/maximum frequency, protection settings) to match the connected motor and AHU duty. After repair, the VFD shall be energised and load-tested with the AHU motor running through its full speed range, checking output current, voltage, temperature rise and absence of fault trips. Panel indications, meters and the cooling fan shall be verified functional. Rate shall be inclusive of new VFD card/spares, transportation, labour, parameter setting, load testing and commissioning, complete per unit as required, all complete as directed by the Engineer-in-Charge.

Repairing and/or calibration of pressure gauges, thermostats and temperature sensors installed on the AHU/chilled water system, to restore accurate monitoring and control of system parameters. The work comprises isolation of the instrument, removal from its tapping/mounting point, inspection for physical damage, dial/needle malfunction, bourdon tube leakage (for pressure gauges), sensor drift or broken capillary (for thermostats/temperature sensors), repair using genuine/compatible spare parts including glass, needle, bourdon element, sensing bulb, capillary tubing and terminal connectors as applicable, and calibration against a certified reference standard to verify accuracy across the operating range. Where repair is not feasible, the instrument shall be replaced with a new unit of identical range, accuracy class and connection size, and specification of the repairing material/spares used shall be furnished to the Engineer-in-Charge for approval prior to fixing. After calibration/replacement, the instrument shall be refitted at its original location with proper isolation valve/pocket, leak-tested (for pressure gauges) and functionally verified against actual system reading. Rate to include spares, calibration charges, labour and testing, complete per instrument as required, all complete as directed by the Engineer-in-Charge.

Supply and installation of dial-type thermometer (0-100 degree C range, 6-inch dial size, bottom/back connected as per location) in the AHU supply air duct, in place of the existing damaged/non-functional unit, complete with stainless steel (SS) ball valve and SS syphon/pocket for isolation and protection of the sensing element. The work comprises removal of the damaged thermometer and its fittings, preparation of the duct/pipe tapping point, supply and fixing of the new SS ball valve and SS syphon of appropriate size and pressure rating, threading/welding as required to ensure a leak-proof connection, and mounting of the new dial thermometer with correct stem length for accurate immersion/sensing depth in the air stream. The thermometer shall be of a reputed make, with a clear white dial, black numerals, stainless steel case and accuracy within +/-1% of full scale. After installation, the assembly shall be checked for leak-tightness (where connected to a wet system) and the reading cross-verified against a reference thermometer. Rate shall be inclusive of thermometer, SS ball valve, SS syphon, fixing accessories, labour and testing, complete per unit as required, all complete in all respects as directed by the Engineer-in-Charge.

Supply and repair of Nitrile rubber pipe insulation of 32 mm total thickness (19 mm + 13 mm, two-layer application) with GC (glass cloth)/aluminium cladding finish, for chilled water/condenser water piping within the AHU room where the existing insulation is found damaged, torn, water-logged or missing, causing condensation and heat loss/gain. The work comprises removal of the damaged insulation and cladding without disturbing the pipe (insulation only, pipe not included in this item), cleaning of the pipe surface of old adhesive, rust and moisture, application of a suitable Nitrile rubber adhesive, and fixing of new closed-cell Nitrile rubber insulation of specified thickness in matching pipe-diameter sleeves/sheets, with all joints, seams and pipe fittings (bends, tees, valves, flanges) fully sealed using self-adhesive Nitrile rubber tape to prevent moisture ingress. The GC cloth/aluminium cladding shall be neatly wrapped and secured over the insulation for mechanical protection. The work is applicable for all pipe sizes as encountered at site. Rate shall be inclusive of insulation material, adhesive, sealing tape, cladding, labour and tools, measured per square metre of insulated surface, complete as required, all complete as directed by the Engineer-in-Charge.