Pneumatic tube transport

by Chris Woodford. Last updated: September 25, 2012.

If you enjoying reading the Sherlock Holmes detective stories, you'll know there's every chance you'll meet a deadly assassin looming on the next page, ready to strike at a moment's notice with his poison-tipped blowpipe. These age-old weapons are classic examples of pneumatic technology: they use the power of compressed air—blowing hard on one end of a pipe fires a missile at high speed from the other end. In the late-19th century, around the same time the Sherlock Holmes tales were first published, blowpipe technology became very popular for sending messages and small objects down much longer pipes linking remote parts of large buildings. In our modern age of fiber-optics and the Internet, you might think this rather quaint "pneumatic transportation" is a thing of the past—but you'd be wrong. Thousands of hospitals, factories, banks, department stores, and other places still rely on pneumatic tube transport to move medicines, cash packets, and other small items with speed, security, and efficiency. One drive-through McDonald's even uses a system like this to deliver burgers to its customers! So how exactly do pneumatic tubes work? Let's take a closer look!

Photo: Need to send cash quickly and securely to another part of your building? You could use a pneumatic transport canister like this. It's made from a tough plastic called polycarbonate, which protects whatever you pack inside. Once the tube is loaded, you screw a cap on the end and place it in the transport tube to be sucked or blown to its destination roughly 5–6 times faster than a messenger could carry it.

What is pneumatic tube transport?

Pneumatic tube systems (also called PTT, airlift, air transport, Lamson tubes, air tubes, and pneumatic transit systems) are amazingly simple—and best illustrated by example...

Suppose you run a large department store full of checkouts (cash desks) that are taking money from customers all day long. To reduce the risk of theft, it's a good idea to collect that money every so often and remove it to a place that's more secure before you deposit it in the bank. You could have a cashier walk around all the checkouts in turn, but that takes time and it makes the cashier vulnerable to robbery. Also, some checkouts will take money more often than others, so it's generally better if the checkout operator dispatches money at regular intervals as it suits them.

A common solution many stores employ is to have a pneumatic tube system linking each checkout with the cashier's department, a strong room often located on a different floor of the building. Every time the checkout operator collects more than a certain amount of cash, they dispatch it securely to the cashier's department using the pneumatic tube.

Photo: Pneumatic tubes have been used at the US Library of Congress since the late 19th century to send requests between readers and the stores where archive materials are held. The system might seem archaic, but it's tried, tested, and efficient—and still used in parts of the Library to this day. Note the two metaldoors opening up for incoming tubes (left) and outgoing tubes (right, and currently being loaded by the operator). You can also see two spare tubes standing at the bottom. Read more about the system in A Series of Tubes from the Library blog, December 16, 2011. Photo courtesy of US Library of Congress.

Advantages and disadvantages

Pneumatic tube systems are a fast, simple, secure, and reliable way of transporting small objects relatively large distances across a building or (using underground or overground pipes) between buildings on the same site. They can move things up, down, or sideways and, because they're pneumatic, provide a soft, air-cushioned ride for fragile items (many systems use air-cushioned brakes or bumpers that bring arriving canisters slowly to a rest at the receiving station). Since they remove the need for a person to carry things, systems like this save time and money and tend to pay for themselves quite quickly. They also offer secure connections between different parts of a building, reducing opportunities for theft and accidental damage in transit.

If they have a disadvantage, it's that the tubes that link stations ideally need to be planned into a building's infrastructure when it's first designed (perfectly possible for something like a new hospital or department store); it's harder (though far from impossible) to install a complex system with many sending and receiving terminals into an existing, older building.

Typical uses

Systems like this are widely used in hospitals and department stores, so those are the places to keep your eyes peeled if you're hoping to spot pneumatic tubes in action. You're most likely to notice them near checkout desks, especially when someone sends a bundle of money off to the cashier's department. Look out for a box (with or without a key lock or numeric keypad) with a tube coming out of the top and disappearing into the ceiling up above. You're unlikely to use a system like this directly unless you work in a bank, store, or hospital, although some pharmacies and banks do use pneumatic tubes to deliver items securely to self-service, electronic kiosks.

Photo: Tubes, ancient and modern! This 1942 photo shows the large-scale transport tube system used to connect the main yard office of the Illinois Central Railroad with other offices nearby. Photo by Jack Delano, U.S. Farm Security Administration/Office of War Information, courtesy of Library of Congress, Prints & Photographs Division, FSA/OWI Collection, [LC-USW3-010495-D].

Find out more

On this website

• Compressors and pumps
• Electric motors
• Hydraulics
• Jackhammers/pneumatic drills

On other websites

Articles

These informative articles are worth a look:

• Series of tubes: Pneumatic Networks Then & Now: Steve Levenstein presents a diverse collection of pneumatic tube systems from the past and present in this article from Web Urbanist (a fascinating illustrated urban art, design, and culture blog).
• Gone with the wind: Tubes are whisking samples across hospital: Sara Wykes explains how a large and very elaborate pneumatic tube system makes life easier at Stanford Hospital.
• The CIA Museum Artifacts: Pneumatic-Tube Carrier: The CIA Museum explains how pneumatic tubes were the Internet of their day!
• Tube freight transportation by Lawrence Vance and Milton K. Mills, Public Roads, Federal Highway Administration, Autumn 1994. This fascinating article considers whether giant versions of pneumatic transport tubes could be used to ship freight over long distances.
• Pneumatic air drive-through McDonald's: BenFrantzDale has put a short video of the infamous pneumatic McDonald's on his Flickr page. Watch the burger guy load a meal into a pneumatic tube and shoot it off to his waiting customer!

Pictures of pneumatic tubes

• Pneumatic tubes: Pictures of pneumatic tube systems on Google Images.
• Pneumatic tubes: Pictures of tube systems, old and new, that people have shared on Flickr.

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