"The status of animals in families has risen dramatically over the last 20 years," says Dr. Arnd Stelljes, Veterinary Director of AniCura Bökelberg GmbH in Mönchengladbach. This is mainly due to the rising levels of isolation among people, who have therefore become much more attached to animals than in the past: "Nowadays, even farmers come to us to have their working dogs operated on!"

Well over 90% of the surgeries at the veterinary clinic are performed on dogs and cats, plus some small pets and birds. "We once had a mini pig that someone kept as a pet" the Clinic Director recalls. "The pig had bladder stones, and we had to operate on a fistula." To do this, the mini-pig had to be X-rayed at the Bökelberg clinic, which is well known within a radius of 100 to 150 kilometers for its imaging procedures. The diagnostic equipment includes CT, MRI, X-ray, dental X-ray and three ultrasound machines, one of which is specifically for cardiology. "We have a corresponding number of medical specialists here," explains Arnd Stelljes. "Radiologists, cardiologists, experts in internal medicine, surgeons, orthopedic surgeons." Performing 15 to 25 surgeries per day keeps the 60-strong AniCura team well occupied.

On the day of our visit, we witness a leg surgery on a cat. The animal is covered by a cloth, with only the tail peeping out. The broken leg is visible under the doctor's surgical instruments. During the operation, the cat feels nothing. It is anesthetized and ventilated in almost the same way as in human medicine: with oxygen and a medication adapted to the animal. Ten anesthesia machines are available to the team. AniCura has been producing the oxygen itself since January 2021, having previously sourced the gas from a separate supplier in 50-liter cylinders for many years. "When a cylinder ran low, the separator in the operating room would start humming because of the drop in pressure," Stelljes explains. Then a member of staff had to rush downstairs to the courtyard, twist open the new bottle, remove the old one and connect a new replacement." This had to be done at least ten times a week, and cost fifteen minutes of work time each time," Stelljes estimates. "Now the oxygen is simply there whenever we need it. No one has to check to see if we need to order new cylinders; we no longer have any fuss or problems with handling and logistics at all!" 

The managing director, who owned the clinic until 2016 before selling it to the AniCura Group, originally had the idea to produce the oxygen in-house many years ago. At the time, however, the site with its 300 square meters of space and only a few surgeries proved too small, and the O2 demand too low. Now the facility covers an area of 1200 square meters. The reason it took some time to install an oxygen station was also due in part to the cylinder supplier: "He was a nice, older gentleman ..." says Arnd Stelljes, referring to the trusting cooperation. And the prices were also "nice" because they were relatively low. "When he couldn't deliver on one occasion, we had to switch to an alternative supplier. That's when we realized how expensive it can get." When the supplier eventually retired, the time had come for Stelljes to switch from cylinder bundles to self-sufficient oxygen production.

The managing director, who owned the clinic until 2016 before selling it to the AniCura Group, originally had the idea to produce the oxygen in-house many years ago. At the time, however, the site with its 300 square meters of space and only a few surgeries proved too small, and the O2 demand too low. Now the facility covers an area of 1200 square meters. The reason it took some time to install an oxygen station was also due in part to the cylinder supplier: "He was a nice, older gentleman ..." says Arnd Stelljes, referring to the trusting cooperation. And the prices were also "nice" because they were relatively low. "When he couldn't deliver on one occasion, we had to switch to an alternative supplier. That's when we realized how expensive it can get." When the supplier eventually retired, the time had come for Stelljes to switch from cylinder bundles to self-sufficient oxygen production.

To produce the oxygen on site, the gas is separated from the surrounding air and enriched in a container. Normal ambient air contains about 21% oxygen, 78% nitrogen, plus smaller amounts of carbon dioxide, argon and other gases. To generate oxygen (or nitrogen), the ambient air is first compressed in an air compressor and then fed to the generator. The PPOG 1 removes the oxygen from the compressed air by means of pressure swing adsorption. This means that the Pneumatech generator separates the O2 from the other gases and enriches it to purity levels of up to 95%. For this purpose, the oxygen generator has two containers, each filled with a special adsorbent. Both are fed with compressed air and alternate between oxygen adsorption (up to a saturation limit) and regeneration. The gas storage container behind the generator ensures a continuous supply of oxygen to the consumers.

At the AniCura Clinic, the compressor is a screw compressor from Alup. Together with a compressed air vessel, various filters and a dryer, it is located in a second small room in the courtyard. "We had planned a cold store here anyway," Dr. Arnd Stelljes explains, giving an insight into the conversion phase. "The two extensions for the generator room and the compressor room made a neat addition."

All the oxygen generation equipment was supplied and installed by Alup's northern branch, based in nearby Erkelenz. The company's specialists also laid all the stainless steel piping for compressed air and oxygen, including all the fittings up to the distribution line. The equipment was then commissioned by Pneumatech, while Alup performed the necessary servicing.

The two-part plant now comprises the following components typical for such a setup:

• Room 1 (in the order in which the equipment is connected): Alup screw compressor, mounted on a compressed air reservoir; wet separation filter (equipped with electric condensate drain, like the compressed air reservoir); adsorption dryer; various dust filters.
• Room 2: PPOG oxygen generator from Pneumatech; gas sampling hose for purity testing; oxygen reservoir and, lastly, an oxygen filter before the gas reaches the taps in the OR and fresh air room via the piping.

Various dryers are suitable in principle for compressed air treatment: a refrigeration dryer integrated into the compressor, a separate refrigeration dryer or—as is the case at AniCura—an adsorption dryer. The latter can dehumidify the compressed air to significantly lower pressure dewpoints than a refrigeration dryer. Tim Ganser, Sales Manager at Pneumatech, recommended a PH-type adsorption dryer from Pneumatech's product line for the project. "We also provide these dryers with Purelogic intelligent controls for remote access and integrated DTP control. However, this equipment is not required at AniCura Bökelberg," says Ganser. The dry, filtered compressed air is fed from room 1 via piping to the generator in room 2.

The PPOG 1 generates a nominal oxygen flow rate of 1.5 m3/h at 95% purity (or alternatively 2.0 m3/h at 90%). AniCura operates with 95% pure oxygen*. The oxygen buffer vessel is an optional component that is used in this case. It has a pressure regulator, a pressure gage and a dust filter. "The flow meters are calibrated and fitted as standard," Tim Ganser explains. "They make commissioning easier and also inform users about their actual oxygen consumption."

When dimensioning the equipment required for the self-generation of oxygen, the number of oxygen cylinders required in the past was used as a basis, plus a certain safety margin, explains Dr. Arnd Stelljes. "My idea was that the equipment should pay for itself in two to four years at the most, and we will achieve that." He adds: "If I had used the high oxygen prices of the other cylinder supplier in my calculations, I would have recouped the investment in just seven months." Overall, the station has been designed "well and generously," the veterinarian underlines. "We can very easily adapt the oxygen generation to accommodate higher demand by, for example, increasing the pressure in the compressor. And if we reach the technical limits and can no longer compress efficiently, we can always mount a larger buffer vessel." With this equipment, AniCura is well positioned for the long term," he adds. Incidentally, Pneumatech was in competition with another supplier during the bidding phase. However, a consideration of the total life cycle costs gave a decisive edge to Pneumatech and Alup.

To expand the system, Arnd Stelljes can also imagine using a "booster" to increase the pressure of the oxygen to a maximum of 200 bar. "Then we could fill the gas generated here on site into cylinders and supply it to other locations in our network where a dedicated generation plant would not be economical." Within a radius of just 50 km, AniCura operates several other veterinary clinics and practices, 70 of them in the German-speaking region (DACH). "In particular, the smaller clinics here in the region could benefit greatly from us," says the AniCura manager. And Pneumatech expert Tim Ganser adds that such a solution—filling the site's own cylinders via pressure booster—would also be interesting "for covering peak loads or as a backup for emergencies." Speaking of emergencies: Stelljes did not have the old cylinder connections removed when installing the new oxygen station. This means that he can connect a gas cylinder to the network again at any time.