Join Our Newsletter - Get important industry news and analysis sent to your inbox – sign up to our e-Newsletter here

Specialist Mechanical Engineers

Custom Military HVAC, Dust and NBC Filtration Systems

907 Hertzog Street
0084 Pretoria,
South Africa

907 Hertzog Street
0084 Pretoria,
South Africa

Specialist Mechanical Engineers (SME) is a South African company specialising in custom military, rail and industrial heat transfer, ventilation, air conditioning (HVAC), as well as high-efficiency dust and NBC filtration systems for use in adverse environmental conditions. We also offer military auxiliary power systems (APUs) for specialised DC and AC requirements.

SME prides itself on having provided an array of qualified military HVAC and APU systems for over two decades in numerous designs, for a wide range of customers within the military industry.

Designs include standalone / bolt-on modular or integrated systems for tanks, armoured personnel / troop carriers, and mobile and stationary support systems. Applications are extended to environmental control systems (ECS) for UAV ground control shelters and panel mount coolers for sensitive electronic racks and power panels.

Vehicle-integrated custom air conditioners

Systems are custom-designed with the client, taking the specific purpose of each vehicle into account. Cabin evaporator designs include fitment options for under seats, against side walls, recessed in floor, roof mounted and integrated in the driver’s console.

Form and fitment are adapted to interface with ducting, diesel burner air heaters and NBC filtration modules. Condensers can be integrated with engine cooling packs or packaged as bolt-on modules. Typical standard capacities are up to 20kW to achieve 22°C cabin temperature in a 55°C ambient.

Modular bolt-on APU and HVAC systems

Many vehicles can accommodate bolt-on HVAC systems, which may often also require an auxiliary power unit. The APUs can be used with water or air-cooled engines, with standard or custom IP44 alternators. Service exchange of units can be within 30 minutes, while armoured steel enclosures are offered as an option and capacity designed to requirement.

Special fresh-air filtration modules can be added for heavy-duty and dusty environments, where self-cleaning cyclone cartridges ensure 95% (or more) clean air to occupants. Similar cyclones are also used on all APUs where the dust is scavenged through a venturi on the engine exhaust system.

NBC filtration is offered as an option with cabin overpressure control and active monitoring by the control system.

Thermal insulation for vehicle cabins and crew compartments

SME can offer thermal insulation for vehicle cabins and crew compartments. The closed-cell product is laminated with a steam-cleanable woven skin, which is silicone impregnated. It is self extinguishing with less than 1% water absorption. A reduction of 40% in heat load is achieved with 12mm thick material. It is available in white, grey and light brown / sand.

High-efficiency scroll compressors

For HVAC systems, the latest technology high-efficiency scroll compressors are used, as well as effective capacity control in accordance with the load. Heating can be supplied by evaporator integrated elements, separate heating or reverse cycle heat pump design.

All units for military applications are developed to operate reliably under extreme temperatures, humidity, shock and vibration and dusty environments. To live up to this standard, all units are performance tested in our climate-control room and also vibration and EMC tested where necessary to ensure optimum performance and compliance with the relevant specifications and procedures.

Efficient power management and communication interface

Intelligent control allows for efficient power management and communication interface options, such as Canbus or custom protocol to the vehicle central management system. Bluetooth and USB links enable download of system history and error logging to reduce fault finding time and potential downtime. The units are also electrically fully protected as per Mil Std requirements.

Product support, training and spare parts

SME offers comprehensive product support with detailed documentation, training at the client’s premises, and reliable spare parts availability up to 15 years if required.

SME strives to deliver HVAC and APU products which are:

  • Military fully qualified to client specifications
  • Have a low lifecycle cost and high MTBF
  • Compact but maintenance friendly
  • Compliant to environmental requirements

12kW Air Conditioning Unit (ACU) for M109 Howitzer

SME's turret mounted modular air conditioning system (ACU) supplies 12kW cooling to ensure a cabin temperature of 22–25°C max in a 55°C ambient, provided the turret is thermally insulated.

21kW Auxiliary Power Unit (APU) For M109 Howitzer

The APU/ACU system does not restrict the standard operational features of the vehicle in terms of firing and mobility. It has its own 28V 120Ah battery pack and 80 litre fuel tank on board.

Compact 3.5kw Auxiliary Power Unit (APU)

Original design from the Patria 8x8 Armoured Modular Vehicle (AMV) and specifically re-designed for the Badger variants for the South African Defense Force.

Air-Conditioning Units for Military Applications

The MSDI8 DUAL is a 16kW, dual-evaporator air-conditioning unit. The evaporators are purposely designed to be an universal coil that can be mounted in multiple positions inside a military vehicle.

Specialist Mechanical Engineers (Pty) Ltd (SME)

907 Hertzog Street




South Africa