Flow and adaptive systems – the origin of Safety Way pressure differential systems

How was the revolutionary Safety Way pressure differential system created? Great ideas require time and an innovative approach. We present the origins of the ventilation system, which has become a recognized and widely used solution to protect staircases in the tallest buildings in Poland and Europe against smoke.

Fire ventilation system effectiveness and the laws of physics

The effectiveness of fire ventilation systems is proportional to the degree to which the laws of physics are considered in their design. The proportion is particularly evident when looking at pressure differential installations that are commonly used to protect vertical escape routes in high and high-rise buildings. Obtaining an appropriate pressure gradient that effectively protects designated building areas (i.e. staircases, fire-rated vestibules and lift shafts) proves to be particularly complex in this case.

Factors affecting system operation

It is due to the fact that smoke prevention systems are impacted by a number of factors, such as fire dynamics (expansion and convection of fire gases), devices and installations (comfort and fire ventilation systems, lift cabin movements), and other phenomena, e.g. air resistance, thermal flow, air leaks through space dividers, etc. And while the first two groups are in fact considered at the design and fire scenario planning stages, the impact of the remaining phenomena on pressure differential systems can only be limited by means of proper configuration and functioning of the installation itself.

The origins of flow systems with the Safety Way adaptive control algorithm

The concept of a new engineering solution was conceived at a trade conference held in spring of 2008 in Poland. At the event, I presented an issue with pressure differential systems previously described to me by a prominent engineer, Iwo Dobrucki (1929–2011). Iwo Dobrucki told me about problems during calibration of those state-of-the-art systems installed in high-rise buildings in Paris.

Expert consultations

The problems pertained to the thermal flow occurring when supplying staircases with air. Due to the lack of an effective solution an unwritten rule was adopted: such installations were not usually accepted in winter when this phenomenon interfered with installations to a greater extent. Jarosław Wiche, the then technical director of SMAY, also participated in the conference. The issue in question evoked his interest and he later became the manager and main architect of the project. SMAY – backed by its general manager, Marek Maj – took on the challenge of finding an appropriate solution for fire ventilation in high-rise buildings.

A study conducted at a testing site in Krakow

Initially, a large number of studies and tests was conducted at a test site located in the Krakow Unity Tower (formerly known as the Skeletor). The test site required a lot of adaptation and construction works, preparing initial air supply control principles, designing special automation solutions, building an installation control and monitoring panel, etc. Within the first three months of trials and tests with various multi-spot air supply control variants we were unsuccessful in providing stable overpressure compensation in the entire staircase. At one point, we were close to ending this costly project.

Utilization of airflow resistance

A breakthrough was finally made when we tested a scenario in which a large volume of air was supplied to a lower staircase while checking what speed could be achieved in the cross-section of an open door on the top floor. It turned out that initial pressure stratification could be eliminated with this configuration. Similar results were obtained in several tests. Long brainstorming sessions, analyses and discussions among members of the research and construction team (Robert Zapała, Grzegorz Sypek, Marek Prymon and Krzysztof Piorun in addition to the project manager) led to the development of physical principles and a construction of a new technical solution. Its concept was based on using resistances of carefully selected and directed air flows in order to limit pressure stratification at the staircase level, caused by the existence of thermal flow.

System functional assumptions

It was a basic concept but it had to be well founded on object and numerical tests. It required building completely new supply and exhaust units, designing control algorithms, expanding the existing site, conducting tens of tests, dedicating hundreds of hours to numerical analyses validated during on-site tests, etc. As a result, a set of functional principles of a new system was conceived. The system was named Safety Way.

Ph.D. Eng. Grzegorz Kubicki

Faculty of Building Services, Hydro and Environmental Engineering at the Warsaw University of Technology


Safety Way: an innovative differential pressure system – escape routes free from smoke and fire – highest degree of protection.
The Safety Way differential pressure system is a solution designed for multi-storey buildings:

• iSWAY-FC® differential pressure product for smoke and heat control systems;
• Innovative predictive algorithm;
• Anti-Frost system that endures even the most extreme weather conditions;
• 24-hour automatic test of all the components;
• Automatic adaptation to changing service conditions;
• Communication between individual components of the set and continuous tracking of all components (regulators, remote pressure sensors, etc.);
• Continuous measurement of the set value of static differential pressure between the protected and reference zones by the P-MAC(F) sensor.

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Growing pains, i.e. how to get sceptics behind new concepts?

At first, designers and firemen considered the principles and features of the new solution inviable. At that time, even Marek Maj wasn’t very thrilled with the results of the venture.

However, the state-of-the-art concept was used in more and more projects and its effectiveness was confirmed. The overpressure flow system ultimately became a well-established and commonly used solution protecting staircases against smoke in some of the tallest buildings in Poland. When after more or less two years following the end of the project I asked Marek Maj if he still was not thrilled with the results, he gave me a smile and replied that he had a change of heart.

New control algorithm for pressure differential systems

One of the growing pains of the above solution was complicated and costly automatic controls responsible for the system operation. However, we found the right man for the job yet again: Maciej Szumski, general manager of Plum. While looking for new solutions for his team of process automation engineers, he ventured to create a completely new control algorithm for pressure differential systems. He then – through the Warsaw University of Technology – contacted the technical director at SMAY. Both companies jointly launched a new research and construction program. After two years of tests (at a specially designed site located in Plum’s main office), a team of software developers led by Maciej Szumski created a control algorithm that proved to be very effective and impervious to interference.

Implementation of a qualitative system of adaptive control

The program led to the implementation of an adaptive control system of the highest quality. Its performance was confirmed e.g. by tests conducted in the I.F.I. Institute of Industrial Aerodynamics in Aachen. The state-of-the-art algorithm practically eliminates any interference and calibration requirements. At the same time, it allows us to adapt air supply units to dynamically changing environmental conditions and evacuation procedures.

Those participating in both scientific projects demonstrated the courage needed to take on a challenge in a field where technical problems remained unanswered. Owing to their hard work, determination and enthusiasm, we can now offer the very first Polish pressure differential system. SAFETY WAY is characterized by its highest quality and technological thought that makes us stand out in Europe and other parts of the world and usher us into the future of ventilation.

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