Installation & Commissioning

Full installation and commissioning of smoke management, exhaust, and HVAC systems, carried out in a fully engineered manner and in compliance with the latest codes and standards.

General Specifications of Centrifugal Utility Fans

These centrifugal utility fans are of the backward-curved impeller type (blades curved to the rear) and are suitable for exhaust and air discharge applications. The casing, base, and rain hood are made of hot-dip galvanized sheet steel. Connections are made by seaming (without continuous welding/filleting). Bases are fastened using galvanized-coated bolts and nuts without any welding. The units are finished with electrostatic powder coating (RAL 7032 – 2004) in accordance with ASTM D1186, with a maximum dry-film thickness of 70 microns. Exceptions are made only where bolting is not feasible for structural reinforcement; in such cases, sheet steel alloys ST37, ST52, CK45, stainless steel, or PVC may be used. When welding is required (CO₂ welding or special electrodes), proper surface preparation is applied and the surface is coated with electrostatic powder paint (RAL 7032 – 2004) to a minimum thickness of 70 microns. 
The inlet cone is conical and extends a few millimetres into the impeller to improve efficiency and ensure proper airflow guidance. 
The backward-curved impeller of centrifugal fans is made of aluminium and is assembled by riveting (no welding). Exceptions apply for high static-pressure applications or models larger than size 100; in these cases the impeller is typically made of ST37 steel alloy and finished with electrostatic powder coating (RAL 7032 – 2004) to a minimum thickness of 70 microns. 
The rain hood on belt-drive models fully protects the bearings, belts and electric motor from rain and snow. Direct-drive fans are fitted with an appropriate motor cover. 
Shafts are manufactured from CK45 steel with a nickel-plated finish. Depending on the order, stainless steel 304 or equivalent material may be used. 
Bearings are of the UCP type, Grade 2.5, tested and supplied with a certificate. 
Drive belts up to size 45 are Type A; from size 50 upward they are Type B. Belts are of Korean or Indonesian manufacture. 
Pulleys are made of suitable aluminium alloy. For models larger than size 90, cast-iron pulleys are preferred. Impeller speed for exhaust duty is selected so that the delivered air volume (without damper) at the specified static pressure is within a maximum tolerance of 5 %, in accordance with international standards. 
Belt-drive (indirect-drive) fans are fitted with an adjustable motor base (as shown in the illustration) to facilitate belt replacement, tensioning and motor alignment during maintenance. 
Outlet (discharge) openings are fitted with metal-mesh guards, finished with electrostatic powder coating or epoxy (as ordered by the customer), to prevent bird entry. 
Electric motors used are of the Electrogen, Motogen or other Iranian brands, with IP54 protection. Three-phase motors are recommended to reduce current draw, vibration, noise level and cost. Explosion-proof motors can be supplied on request. 
Impellers are statically balanced and dynamically balanced using a portable balancing machine in accordance with ISO 1940, Grade 2.5, and are supplied with a balancing certificate. 
All fans are equipped with a double chassis and suitable anti-vibration mounts or supports to minimise vibration transmission. 
Lifting hooks are provided for ease of handling. All units are fitted with a terminal box; an isolator switch can be mounted inside the casing on customer request. 
All moving parts are covered by a 12- to 18-month warranty, provided the equipment is installed and maintained correctly in accordance with the warranty conditions. 

Outlet air velocity is selected according to customer requirements. 

Outlet velocity of utility fans is calculated by the following formula: 

Outlet velocity (FPM) = Air volume (CFM) / Outlet area (ft²) 

Note: Outlet (discharge) velocity of these fans shall comply with the values given in the table below. 

For kitchen-hood exhaust applications, air volume is calculated per square foot of hood area according to the table below. 

Hood mounting height above the kitchen floor shall not be less than 180 cm. For the TBAL 80-12 SB model the fan outlet dimensions are 51 × 100 cm, equivalent to 1.673 × 3.281 ft. Outlet velocity is therefore calculated as follows: 

V = 7500 / (1.673 × 3.281) ≈ 1366.34 FPM 

Note 1: When selecting a fan, impeller diameter must always be carefully considered, because outlet velocity is directly related to fan diameter. Selecting a fan with a diameter smaller than required reduces the outlet area and therefore increases outlet velocity. In this case the impeller must run at a higher speed to deliver the required volume, and both factors result in higher noise levels. 

Note 2: Forward-curved impeller fans must never be used for air extraction (suction) duty. 

First reason: The closely spaced blades of a forward-curved impeller readily accumulate sticky substances such as grease on the suction side. This increases impeller weight over time, severely reducing efficiency and capacity. 
Second reason: Forward-curved fans deliver higher volume than backward-curved fans of the same size. Consequently, for a given capacity a forward-curved fan has a smaller diameter, resulting in a smaller outlet area, higher outlet velocity and therefore higher noise. 

Forward-curved fans should therefore be used only for supply-air applications, never for exhaust or extraction. 

The Mackesh & Dahesh calculation software provides calculations of air volume, pressure drop, air velocity, sound level (dB), actual motor power consumption, performance curves, dimensions and final technical specifications. 

The electric motor carries a one-year warranty from the original manufacturer. It is recommended that a control panel equipped with safety devices and phase-failure protection be used. 
During commissioning, check the direction of impeller rotation (arrow marked on the unit). 
After connecting the power cable according to the fan’s electrical data, measure the running current to ensure it does not exceed the motor’s rated maximum current. Verify that all motor terminal connections are correctly made and tightened. 
Use of a control panel fitted with contactor, thermal overload relay, phase-failure relay, manual on/off switch and other safety devices is mandatory. 
A proper foundation must be constructed according to the weight and dimensions of the unit (preferably 20 cm larger than the fan chassis on each side), provided with steel base plates for connection to the secondary chassis, and must be perfectly level. Placing the fan on any surface without a proper supporting structure is not recommended. 

Roof-Mounted Centrifugal Fans (Backward-Curved) 

These roof-mounted centrifugal fans are of the backward-curved impeller type and are suitable for exhaust and air-discharge applications. The casing and base are made of hot-dip galvanized sheet steel and are assembled with galvanized bolts and nuts without welding. Exceptions are made only where bolting is not feasible for structural reasons; in such cases the appropriate sheet alloys or PVC may be used, and when welding (CO₂ or special electrodes) is required, proper surface preparation and electrostatic powder coating (RAL 7032 – 2004) to a minimum thickness of 70 microns are applied. 

The inlet cone is conical and extends a few millimetres into the impeller to improve efficiency and guide the airflow correctly. 

The backward-curved impeller is made of aluminium and is riveted (no welding), except for high-pressure applications or when specifically ordered by the customer, in which case it is painted. 

The rain hood is manufactured from aluminium, circular for direct-drive and belt-drive models, and square for belt-drive models sizes 45–100. It must be larger than the main fan casing and fully cover it so that rain or snow cannot enter the duct system. 

Shafts are made of CK45 steel with nickel plating. Depending on the order, original Japanese stainless steel 304 or equivalent imported material may be used; a grease-nipple hose can be fitted on customer request. 

Drive belts up to size 45 are of the appropriate type and of Korean or Indonesian manufacture. 

Pulleys are made of suitable aluminium alloy; for larger models the appropriate material is used. 

Impellers are statically and dynamically balanced with a portable machine in accordance with ISO 1940 and are supplied with IP65 protection where specified. 

All moving parts are covered by a 12- to 18-month warranty, provided the equipment is installed and maintained correctly. 

For hospital projects the impeller tip speed of roof fans is generally limited to a maximum of 3500 FPM. Tip speed is calculated by the formula involving π. 

The electric motor carries a one-year warranty from the original manufacturer. Use of a control panel with safety devices and phase-failure protection is recommended. 

Check impeller rotation direction (arrow marked on the unit) at start-up. 

After connecting the power cable according to the electrical data, verify that the running current does not exceed the motor’s rated maximum. Ensure all motor terminal connections are correctly made and tightened. 

A control panel with contactor, thermal overload, phase-failure relay, manual switch and other safety devices is mandatory. 

A proper foundation sized according to the unit weight and dimensions (preferably 20 cm larger than the chassis), fitted with steel base plates for the secondary chassis and perfectly level, is required. Installing the fan without any supporting structure is not recommended. 

Impeller cleaning shall be included in the maintenance schedule and performed at least once a year. 

It is recommended that installation, commissioning and periodic servicing be carried out by qualified specialists. 

Principles of Jet-Fan Installation in Car Parks 

The greater the available clear height in the car park, the more flexibility exists in system design and equipment selection. Jet fans may be positioned between roof beams to minimize the overall system height. 

Ceiling obstacles must be taken into account in car-park ventilation design.

Requirements for jet-fan layout: 

When locating the main exhaust points, the positions of exits and escape routes must be considered. The layout shall not endanger exits or escape paths. 

Design shall ensure that air velocity in escape routes and ramps does not exceed 5 m/s, so that the safe egress of occupants is not impaired.