Pneumatic Tube Station Product

Overview

A pneumatic tube station is one endpoint of a building-wide capsule transport system. Hospitals are the dominant users — blood samples, medications, and lab results move between wards, pharmacy, and laboratory in minutes without a human courier — with banks (drive-through tellers), supermarkets (cash skimming), and factories close behind. The station is where a user loads a Capsule Carrier, keys a destination on the Operator Panel, and where arriving carriers land softly in a Receive Basket.

The propulsion is elsewhere: a central blower per line generates pressure or vacuum of 150–300 mbar, and the station's job is to inject carriers into the line, manage the air, and brake arrivals. A 110 or 160 mm PVC tube network with motorized Line Diverter switches connects dozens to hundreds of stations through a tree of lines, coordinated by a master control computer.

Sending a carrier

The user opens the interlocked Send Door, drops in a loaded carrier, and enters the destination address on the Destination Keypad. The Station Controller requests the transaction from the system master over its RS-485 Bus Transceiver. When the line is free, the master commands every diverter along the route to its position — each Diverter Tube Segment segment swings under Servo Motor drive and confirms alignment with Hall Sensor feedback — then tells the blower station to apply air.

Direction is set by the Air Shift Valve Unit. The Air Shift Valve connects the blower to the line either as pressure behind the carrier (push) or suction ahead of it (pull); a single reversible air column can therefore move carriers both ways through one tube. The carrier's Wear Band Set — felt or elastomer rings at each end — seal it against the tube bore so the modest pressure difference produces a usable force: roughly 0.2 bar across a 110 mm bore yields ~190 N, plenty to push a 3 kg capsule up a vertical riser. Normal transit speed is 6–8 m/s; systems carrying blood switch to a 2–3 m/s "gentle" profile because high deceleration hemolyzes samples.

Receiving

Arrival is the hard part. A capsule at 7 m/s carries real energy, so the station never lets it hit a hard stop. As the carrier approaches, the Air Bypass Valve bleeds the driving air and the trapped column ahead of the carrier in the Arrival Air Damper acts as an air spring, decelerating it over the last metre or two. Carrier Photo Sensor beams report the carrier entering the chamber; the Carrier Release Gate holds it until line pressure equalizes, then drops it into the padded basket. The station chimes through its Speaker and lights the arrived lamp on the Status LED Cluster.

Each carrier embeds a Carrier RFID Tag, read at stations and diverters. The master uses it to confirm the right capsule reached the right address, to log chain-of-custody for medications and cash, and to route empty carriers automatically back to stations that are running short.

The carrier

The Carrier Body Shell is clear polycarbonate so staff can see contents without opening it. The Carrier Lid is hinged or bayonet-twist; hospital variants add an inner sealed liner so a leaking sample tube cannot contaminate the tube network. The Lid Latch must hold positively — a lid opening mid-transit at a diverter is the classic system-jam failure. Wear bands are consumables, replaced when transit times start drifting because air leaks past the seal.

Control architecture

Stations are simple peripherals; intelligence is central. The station Microcontroller runs door interlocks, sensors, and valve Relay outputs, and exposes everything to the master over the RS-485 loop (Ethernet on current systems). The master schedules one carrier per line segment at a time, queues requests, and on multi-line systems hands carriers across transfer units between lines. Priority classes let a stat blood-gas sample preempt routine document traffic. Modern installations report into hospital IT: every send and receive is timestamped, and pharmacy systems reconcile dispatched medications against tube-system delivery logs.

A typical hospital system moves several thousand carriers a day; the per-trip economics (seconds of blower time versus a 10-minute staff walk) are why a transport technology patented in the 1850s still gets designed into new buildings.