The pneumatic tube – this is how it works

The history of pneumatic tube systems can be traced back to the 1850s. The first operating system was built by engineer Josiah Latimer Clark and went into operation at the London Telegraph Office in 1853. Shorter paths for rapid transport were created: Letters, telegrams and even parcels were put in cylindrical containers and sent through the tubes. Colored markings served as identification for the various shipments.

Particularly for the stock market, it was an important and, above all, fast method of communication at that time: if messages were not delivered in a timely manner, speculators ran the risk of losing a fortune. More and more pneumatic tube systems were also used in retail trade, banks, and the chemical and automotive industries – mostly to transmit production samples to laboratories. High quality was ensured.

In the course of the 19th and 20th centuries, the air system became established in other cities besides London. Mail was sent by the Prague tube network until 2002 – the longest time an air system was used for mail deliveries. However, transport through the underground became increasingly difficult over the years. More and more disruptions occurred, individual tube sections shifted underground and maintenance work became more complicated.

Today, the system is mostly used for fast and reliable intralogistics. The goal remained the same as in the past: Overcoming distances with fast and safe transport.

The concept of a pneumatic tube system has not changed since its development many years ago: each system is powered by air. One or more air compressors and a network of different delivery tubes form the basis of every system. For carriers that need to be transported several floors upwards, compressed air is required. To transport pneumatic tube carriers to a lower floor, it is sucked in by the help of air. Horizontal transport works with both compressed air and by suction depending on the system. The pneumatic tube software is used to transmit information about the level where individual pneumatic tube stations are located as well as where to transport the individual carriers.

Most installations that operate with an air compressor use air diverters. These are usually located above the compressor and regulate whether the carrier in a pneumatic tube system is conveyed by compressed air or by suction. The air switches are thus responsible for the air compressor to change from pressure to suction and vice versa.

Several switches in the individual transport pipes ensure that the correct station is addressed. As soon as a carrier is routed to another branch of the tube, the information is transmitted via the pneumatic tube software. Frequency converters on the blower are used to prevent containers from being transported too fast. They slow down the journeys within the pneumatic tube network, preventing the carrier and its contents from being damaged.

Large pneumatic tube systems that cover several buildings and floors usually require several transport lines and blowers. The transport lines operate similarly to the routes of a subway network. Individual carriers often have to change lines to reach their destination. By means of transfer units, a possibility to leave one line in order to continue on another is created. This compact crossing allows an automatic exchange of containers between several lines.

Special particle filters are used to clean the air inside a pneumatic tube system. Microscopic particles such as dust or pollen are removed from the transport tubes.

Especially in hospitals, pneumatic tube systems still play an essential role. Even though state-of-the-art technology is used in many medical areas, the well-tried mode of operation of pneumatic tube systems still handles a large part of the critical intralogistic transport routes in hospitals. The quality of transport of goods is extremely important, as misdelivered goods or improper handling during pneumatic transport negatively impact logistical operations, staff efficiency and patient care.

The pneumatic tube system ideally connects all wards, surgical rooms and departments with the hospital's laboratory and central pharmacy. It significantly shortens delivery times and handles two of the most important material flows in the hospital – diagnostics and therapy.