By Johan Bekker, project engineer at Hi Calibre Engineering

The temperature control of the indoor environment at Nkunzi Pharmaceuticals’ 940m² Warehouse 1 was found to be inadequate and Hi Calibre Engineering was appointed to upgrade the facility. The scope was to bring the warehouse up to par with good warehousing practices, specifically environmental control.

Johan Bekker, project engineer at Hi Calibre Engineering.

Johan Bekker, project engineer at Hi Calibre Engineering. Image credit: © Eamonn Ryan/RACA Journal

The project began in July 2021 and commissioning was completed in July 2022. Nkunzi Pharmaceuticals, located in Wadeville, Germiston, is a manufacturer of pharmaceutical products.

This included remedial work done to the warehouse, installation of an Environmental Control System (ECS/HVAC system) that would maintain an indoor temperature between 15°C and 25°C and allow for future expansions to the warehouse, and a validated Environmental Monitoring System (EMS).

The client’s brief was for the design and execution of the scope of work below:

  • The installation of an Environmental Control System, necessary to maintain the 940m² Warehouse 1 between 15°C and 25°C, and also to supply sufficient fresh air to comply with SANS requirements.
  • The installation of a new independent Environmental Monitoring System to monitor and alarm when environmental conditions approach the upper and lower temperature limits for the facility.
  • The EMS should provide live access to current temperature conditions as well as the ability to generate reports for any period, on any of the loggers.
  • Remedial work to the interior walls, painting of the walls, remedial work to the floors and application of a self-levelling epoxy screed to a section, and installation of a new ‘Lambda Board’ ceiling for the entire extent of the warehouse.
  • Removal of outdated fire suppression hardware and the revamp of the flammable store.
  • The installation of a new roller shutter door, and integration of the controls into the biometric access system.
  • Dust generation was to be kept to a minimum with no debris allowed to touch any of the packaged materials in the warehouse.
  • Isles between racks and all walkways were to be kept clear during construction as normal factory operation needed to continue throughout the project, except for a December shut down when the floors were remedied.
The legacy system.

The legacy system. Image credit © Eamonn Ryan/RACA Journal

The HVAC/R system(s) and installation

The HVAC system comprises a 197kW air-cooled rooftop packaged unit that is of a split arrangement, to allow better positioning in a limited space. This unit is mounted outdoors on top of a newly cast concrete mezzanine structure and connected to rigid supply and return ducting that penetrates the building.

Inside the warehouse, the rigid supply ducting runs down the length of the warehouse with six fabric duct branches ranging from it. Each branch off has a static balancing damper that was set using a hot wire anemometer through a hole in the fabric ducting to determine the airflow. After the balancing damper is the VarioDuct fabric ducting supplied by FabricAir, the first such installation in South Africa. The VarioDuct consists of a rigid collar section that has a vane, connected to an actuator, on the inside. This vane attaches to a diaphragm inside the VarioDuct. The fabric ducting has small, dense perforations on the top and large holes on the bottom to promote different styles of air distribution. The fabric ducting is suspended using suspension method 1: clips that attach to a single cable that is anchored on both walls on either side of the warehouse and running over the rigid supply ducting.

C21066-HV-GAD-001-01-REV00-Ducting Layout_As Built

Image credit Hi Calibre Engineering (Pty) Ltd

C21066-HV-ISO-001-01-REV00-Ducting 3D View_As Built

Image credit: Hi Calibre Engineering (Pty) Ltd

The rigid return air ducting is arranged in a tuning fork configuration, running against the walls of the warehouse, parallel to the rigid supply duct. Return air grilles are installed at regular intervals, facing downward or horizontally into the warehouse, depending on the underlying racking and available space. This was done to promote airflow through the central racking.

The Rooftop Packaged Unit has a mimic screen installed inside the warehouse to monitor alarms and adjust setpoints. A switch was also installed on the same panel that switches the VarioDuct system between summer and winter conditions. Future automation of the summer/winter switch is possible when a BMS system gets implemented.

The EMS system, Saveris 2, is a Code of Federal Regulations Title 21 Part 11 (CFR 21 Part 11) accredited monitoring system that is suitable for pharmaceutical use and the first installation in South Africa. It was installed by Testo to monitor the performance of the EMS system.

Elements of difficulty in meeting design specifications/installation were as follows:

  • All remedial and installation work had to happen alongside the normal operation of the factory.
  • As the supply ducting is at a height above 7m, a challenge was presented with getting hot air down to the floor during the winter, without forming hot pockets at high levels during summer.
  • Determining where the EMS loggers would need to be located.
C21066-HV-SAE-001-01-REV00-Ducting Sections_As Built

Image credit: Hi Calibre Engineering (Pty) Ltd

Products selection and criteria:

A net with a platform inside was suspended directly underneath the ceiling and a tarpaulin was suspended underneath it to catch any debris or tools. This allowed for unrestricted access underneath for normal factory operations to continue (IBC).

VarioDuct from FabricAir was selected as it offered a solution for its adjustable configuration. In the summer, cooled air is allowed to flow from the top of the fabric duct through many small perforations. The cool air then drops to the floor while displacing hot air to the top where it gets drawn in through the return air grilles. In the winter, warmed air gets forced to a low level through nozzles on the underside of the fabric ducting that were precision engineered to result in the required throw of the air (7m down). The warm air again rises to be drawn in through the return air grilles.

Testo was appointed to do a detailed temperature mapping of the facility, placing 42 temperature loggers across the warehouse. From the results, hot and cold spots could be identified, and permanent EMS probes installed here.

The heat load of the warehouse was determined by calculating the number of people working in the warehouse, the heat generated by the electrical forklifts and solar heat gains through the ceiling and external walls. The effect of the solar heat through the ceiling was also addressed by installing Lambda Board inter-purlin as close as possible to the roof sheeting while maintaining a safe distance from the fire sprinklers. Outside air introduced to the system to comply with minimum fresh air requirements was also considered.

The Varioduct fabric ducting and Testo Saveris 2 EMS were both installed here for the first time in South Africa.

Dave Mitchell, franchisee of FabricAir in South Africa.

Dave Mitchell, franchisee of FabricAir in South Africa. Image credit FabricAir

The FabricAir VarioDuct

By Eamonn Ryan with technical input from Dave Mitchell, franchisee of FabricAir in South Africa.

It is a diffuser of air as opposed to a transporter of air.

To quote from FabricAir’s product description, “The FabricAir VarioDuct provides different flow models for cooling and/or heating purposes. It is tailored with an internal membrane that separates the two airflows. Depending on which flow pattern location is needed, a damper changes position and moves the internal membrane either up or down covering half the duct.”

Two solutions in one duct solves the basic challenge. Hot air rises, thus heating requires nozzles or jets to deliver hot air in the target zone without drafts. Cold air falls, thus cooling requires smaller perforations or orifices to ensure draft-free comfort.

Thus, VarioDuct optimises comfort all year long, providing exceptional comfort levels without any compromises. Switching from heating to cooling is seamless, guaranteeing a consistent and enjoyable environment. With full flexibility in terms of air volumes, pressures, and temperatures, VarioDuct adapts to specific needs. The design incorporates two distinct sections, each customised with unique flow models. Each section can have its own static pressure and air volume, thanks to a specialised internal membrane that separates the two airflows. By utilising a damper, the membrane covers half of the duct, allowing for varying temperature differences (Δt) between the sections. No matter which section is in use, the system ensures an exceptional level of comfort that surpasses expectations.

The rigid supply duct with fabric ducting branching off. The suspension cable and balancing dampers are also visible.

The rigid supply duct with fabric ducting branching off. The suspension cable and balancing dampers are also visible. Image credit: © Eamonn Ryan/RACA Journal

Fabric ducting

Dave Mitchell, franchisee of FabricAir in South Africa (for the moment, as his company Environmental Ducting Solutions is being acquired directly by Danish company FabricAir to become a 100%-owned office), says, “This particular project is one of many that we’ve done with Hi Caliber Engineering, starting with a PepsiCo project in Isando approximately eight years ago.

“The VarioDuct system installed at Nkunzi Pharmaceuticals is the first installation of its type in South Africa. It’s relatively new on our list of products, having come onto the market about two years ago. It’s specifically designed to be versatile in summer and winter where we have the widely varying ambient temperatures creating a challenge of getting air to a comfortable level, particularly so in winter.

The Belimo actuator mounted to the damper shaft that is attached to the membrane.

The Belimo actuator mounted to the damper shaft that is attached to the membrane. Image credit: © Eamonn Ryan/RACA Journal

Crossing the line, where the works commenced.

Crossing the line, where the works commenced. Image credit: © Eamonn Ryan/RACA Journal

Dunham-Bush AHU 100 condenser.

Dunham-Bush AHU 100 condenser. Image credit: © Eamonn Ryan/RACA Journal

“There is a servo motor on the duct which drives the diaphragm within the duct. In summer it will allow the hot air out of the top half of the duct and the cold air will naturally fall – which is what drives the air down to comfort-level. In winter, the top half of the duct is shut off with holes in the bottom half that opens the bottom holes, releasing the pressure so the airflow flows down, forcing past the cold air to the comfort level where the people are,” explains Mitchell.

“It is not a new technology, I’ve been the distributor for FabricAir in South Africa since 2014. The company is 50 years old with its head office in Køge, Denmark, and its factory in Lithuania, where its entire global production takes place. FabricAir currently has subsidiaries in 16 countries and a large network of distributors that reach customers in over 120 countries.

“Every ducting system is specially designed and built for a project. In the case of Nkunzi, because it’s a pharmaceutical warehouse with the ducting high up, there were concerns about getting heating to the bottom in winter. That’s why our product was selected. With conventional ducting system at heights, the efficiency changes with the seasons and becomes less effective in winter.

“This particular project was not one with a tight deadline where they needed everything yesterday. Many projects of course are like that, and we can deliver on average within 15 days from acceptance of the order, for any size project anywhere in the world.” He explains that because of the light weight of the fabric ducting, it is viable to airfreight it in – bypassing all the logistical delays with shipping over the past two years.

“It looks large when installed, but in fact for transport folds up small and fits in a few standard-sized boxes which may be carried easily on site. Notwithstanding that, the nature of the fabric is highly durable as it has a better lifespan than many metal products. One of the original FabricAir systems first installed in Denmark has been running for 40 years.

Testo system.

Testo system. Image credit: © Eamonn Ryan/RACA Journal

“The fabric never has to be replaced. It’s a specially developed polyester fabric of which there are many different types from standard fabric to antimicrobial. Fabric ducting was initially developed for food industry manufacturing processes in Denmark. Working in food processing plants is often uncomfortable for workers because of the cold temperatures of anything from 16°C down to 8°C. The chill factor of air conditioning can take that to almost freezing point. This means workers can’t work long shifts and also get sick from regular exposure to different temperatures. In one study at pork producer Danish Crown, for instance, sick time off was reduced by as much as 30% just by using fabric ducting.

“The other advantage of fabric over metal is its ease of installation. As it’s lighter, it can be installed about five times quicker than traditional steel ducting, almost ‘plug and play’.

Contrary to traditional metal ducts, the entire fabric ducting works as a diffuser. In metal ducting, the cold air with ΔT=7-10°C is coming out from the diffusers with very high air velocities (7-15m/s) and creates drafts and hot/cold zones.”

Fabric ducting eliminates drafts and hot/cold zones by uniform air distribution and minimising temperature differences through the occupied area as low as 0.5°C.

It is also the more energy-friendly technology on the market, as the lower pressure drop, high precision and optimised mixing offered by the fabric ducts consumes up to 40% less energy compared to conventional metal ducting.

Mitchell notes the system is not appropriate everywhere: “It is not viable where ducting is required in a ceiling, even though the fabric is fire retardant fire ratings do not permit it. Also, because the fabric ducting is permeable and air emanates everywhere, it can create dust from the ceiling. It also cannot be used externally. It is ideal for the open architecture of a large warehouse or retailers operating from large open warehouse-type premises such as a Builders Warehouse.

“It is almost maintenance-free – it can be taken down and laundered and many companies simply keep a spare set of ducting and replace them for laundering,” he says.

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