Tubes for the 21st century
At NIH center, software manages pneumatic delivery
- By William Jackson
- Feb 14, 2008
DATA IS THE COIN of the realm in the Information Age's service-based economy.
It is broken into bits, put into packets and routed via packet-switched networks to its destination.
But what about moving things in the physical world? The National Institutes of Health move thousands of blood products, biological samples, medications and medical devices every day between patient care units and the pharmacy, laboratories and other departments at its Clinical Research Center (CRC) in Bethesda, Md.
These vital items can't be e-mailed, and center officials didn't see value in having doctors, nurses and clerical staff deliver the items throughout the two-building complex's nearly 3.4 million square feet. Instead, much of the material is packed into plastic carriers that are routed through a system of pneumatic tubes to their destinations.
'It's cheaper to move these things around by tube than to have people do it,' said Lawrence Eldridge, now executive director at NIH's Edmund J. Safra Family Lodge.
Eldridge, then an assistant to the CRC's chief operating officer, helped with the design of the pneumatic system when the center was remodeled several years ago.
'Today, the building depends on it, and people depend on it,' said Jim Wilson, chief of facilities management at NIH. 'People don't want to log on to their computers in the morning and see that the network is down. And people don't tolerate that in the tubes, either.'
If you are old enough to remember paper checks and cash, you probably recognize this technology from drive-up windows at banks, where tubes and carriers moved money and paperwork between cars and tellers.
If you are a little older, you might remember tube systems in department stores, where they connected the sales floors with stock rooms and financial offices, or in newspaper offices, where they moved copy from the newsroom to the typesetting and composing departments.
But the NIH tube network is not your father's or grandfather's pneumatic tube system.
The NIH system uses a bank of nine 10-horsepower blowers in the CRC's subbasement to create the vacuum and pressure used to push and pull plastic carriers at 25 feet per second through the network of 6-inch tubes.
Proprietary software schedules and routes the carriers, much like a packet-switched network, from any source across multiple transfer points to any of more than 50 individually addressable destinations.
It selects the most effective route based on distance, number of hops, volume of traffic and priority of the carrier.
The market for pneumatic tube delivery systems has never died, said Craig Swank, communications director at Swisslog USA, a company whose roots date to 1912.
Swisslog built the NIH Translogic pneumatic system, and hospitals are the company's bread and butter.
'You can find them today in any health care facility over 75 beds,' Swank said.
The company introduced its computer-controlled systems in 1969.
'That changed the landscape,' Swank said, by enabling station-to-station routing rather than a hub-and-spoke configuration with carriers transferred at a central station.
The latest version of the software, TL2007, runs under Microsoft Windows and uses sensors in the tubes to track each carrier across the tube network. Access controls also are available, requiring a recipient to enter a personal identification number to retrieve a carrier containing controlled substances or sensitive information.
The company had to spend about 10 years during the 1970s and 1980s educating their customers, many of whom were abandoning antiquated tube systems.
But the market picked up in the early '80s, and the company's annual revenues have grown since 1983 from about $15 million to about $40 million.Hangars and hospitals
Most of that business has come from hospitals.
But Swisslog also has some installations in airport repair and maintenance centers, where airlines use them to move parts to maintenance hangars.
About 80 percent of the parts needed to keep a plane in the air can be moved through a 10-inch tube, Swank said. But 'nothing beats the logistics speed of this in a hospital.'
Traffic volume at CRC ranges from fewer than 1,000 transfers a day to more than 1,500, depending on the day of the week ' Wednesdays and Thursdays typically are the busiest, and activity drops off sharply on Mondays and Fridays. But a large hospital might see 7,000 to 10,000 transfers a day.
'The manpower for that would be overwhelming,' Swank said. 'It would take a big courier staff. In a lot of cases, it is being done by professional staff.'
That would be an unacceptable waste of professional resources, Wilson said. 'It's a labor saver.'
The pneumatic tube system, which was installed in 2002, was incorporated into the design of the new CRC, which now houses patient facilities at NIH.
A material management consultant was hired to help design the new system. The older clinical center, which was incorporated into the new facility, already was using a 4-inch pneumatic system.
'They recommended that we go to a 6-inch carrier,' Eldridge said. 'That was becoming the new standard.'
The larger, 6-inch carrier has a 7-pound capacity compared to the 2-pound capacity of the 4-inch carriers, and it can also handle bulkier materials. CRC considered keeping the 4-inch system in some areas but decided upgrading to a single, larger system made more sense.
The NIH system is divided into nine strategic zones, each with a series of addresses for stations.
Swisslog designs the zones based on extensive user interviews and software simulation of traffic. Each zone has a dedicated blower that can reverse directions. A vacuum dispatches a carrier from the sending station to the transfer point, where carriers are staged and switched between zones. From there, pressure is used to blow it to its destination or to the next transfer point.
Only one carrier is moving through the tubes of a zone at any given time, but a number of carriers can be stacked up at the transfer points waiting their turn.
CRC has 53 stations, and pneumatic tubes crawl throughout the complex from the subbasement to the 13th floor.
Within a zone, a carrier can take one or two minutes to make a trip, depending on the volume of traffic, said Pamela Kowal, an electronics mechanic who helps maintain the system.
Between zones, it takes five to seven minutes, depending on the traffic and the number of hops required.
'The computer sets the path,' she said. Priorities can be designated so a higher-priority carrier can bump others waiting to move through a zone.Secure transfers
Although NIH could use PIN-based access controls to transport controlled medications via the tube system, they are not using it that way. Eldridge said the pharmacy wanted to get used to the new system before adding that additional layer of complexity.
'We are probably at the point where we could go to the pharmacy and ask them if they are interested,' he said.
But the secure transfers also would slow other traffic in the zone. 'You would have to increase the waiting time for non-secured transactions a lot, so they haven't felt compelled to have that feature. In busy times, it would work against us.'
So the pharmacy continues to manually transport controlled medications.