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Frequently Asked Questions

Ultra-Controlo is one of the leading companies working on vacuum, compressed air and purification systems for more than 30 years.

Our answers will always be given according to our knowledge and we will always encourage you to offer the best solution taking the people who will need the systems in the hospitals. Please fill the obligation to inform the decision makers about the right solution on behalf of your community. A good decision taken today will result in benefits for thousands of people along decades!

If you need an answer for a question that is not here, please ask Ultra-Controlo.

What is the best compressor for medical air?
What is the best vacuum pump for medical use?
Does Medical Air require purification?
How dry does medical air have to be?
Can one use Refrigerant Dryers with Medical Air?



What is the best compressor for medical air?

The best compressor for medical air is without any doubt a two stage reciprocating oil less compressor with cast iron body and wet-parts iron-free and stainless steel non-return heads valves. An oil free tooth machines is not really a totally oil-free unit as these compressors carry a lot amount of oil in the gearboxes and most often these compressors gets oil leakages and oil spillages forming an oil bath after a while. This oil is sucked in the air-end inlet port and at high compression temperature like the two-stage tooth compressors the oil is vaporized and can cross through the entire filtering system and reach the air terminals. Water injected screw compressor can be the second choice if the system capacity is really high. It is a non-sense to use oil-lubricated compressors that inject oil into the compression phase and at the end to the outlet port and have to install a special filtrations system just to remove oil and derivates. Hospitals carry a very hard risk when they accept such compressors in the medical air supply system. A lot of moving parts, filter elements, desiccant cartridges, oil separators, oil and so on must be changed in regular base due to the presence of oil. It has to include the regular cost for air quality measurements. At the end it is a lot of expenses and it doesn’t serve the purposes of the protecting health laws. A two stage oil-less piston compressor with cast iron body is the best choice.

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What is the best vacuum pump for medical use?

With the different pump technologies available we can say that almost all fits to medical use. Claw technology seems to be the most efficient in energy savings and spares, however has the most expensive initial investment. Hospitals that wish to reduce operating costs (energy, spare-parts and service) should think on changing their obsolete systems. Dry running rotary vane vacuum pumps seems to we be ideal for places with small size hospitals and when one wish to extend the service intervals. Liquid ring vacuum pumps are mostly used in countries where water source is available and therefore no spares are required for the pumps. Nowadays it is usual to supply complete liquid ring vacuum systems with oil as service liquid, so water source is no more required. Oil lubricated rotary vane vacuum pumps are of course the first choice all over the world due to high performance and reliability. However a vacuum pump that doesn’t need tools or gaskets for preventive maintenance, so to say, with external oil separator element system without the need of an oil filter too, should be the best choice regarding time and money savings.

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Does Medical Air require purification?

Yes of course, a cubic meter of air at 7 bar may contain around 28 million particles. If you include water present in the atmosphere that is a real contaminant as well as oil in lubricated compressors. Last but not least, if the supply system is near to surrounding parking areas and so on, there is no doubt that a purification system is a must and you have to be aware that regular service and replacements are needed. If the medical air system is composed by oil-less compressors with two stage air compression and if the atmospheric air is coming from a very clean area, you need the purification unit with -40ºC, but the service intervals will last much more due to the “clean” conditions you have. So as far as you use a good purification system combined to a good double stage oil-less compressor, the less concern you will experience with the medical air quality delivered. It will quite sure exceed or stay within the parameters of the International Standards like ISO 7396-1.

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How dry does medical air have to be?

According to studies, warm, moist air provides an ideal environment for the growth of micro-organisms. Bacteria and viruses are also brought into the compressed air system through the compressor intake. Ambient air can typically contain up to 3,850 micro-organisms per cubic metre. If only a few organisms were to enter a clean environment, sterile process or distribution system, enormous damage could be caused that not only diminishes system integrity, but may cause serious physiological detriment. A pressure dewpoint of better than -26°C, (-15°F), will inhibit the growth of micro-organisms within the compressed air system, however a refrigeration dryer cannot achieve these low water vapour levels, so a desiccant dryer must be used for breathing and medical air applications. Tests have been performed and have shown that the performance of the catalysts used for CO removal, are greatly affected by the presence of water vapour. A new catalyst element that has been vacuum packed can remove an inlet challenge of 65 ppm carbon monoxide in air down to the European Pharmacopoeia limit of 5ppm for breathing air. However, a catalyst unit was left exposed to the atmosphere to allow saturation with water vapour and then tested in the same way. The “aged” cartridge could only catalyse 15ppm carbon monoxide as an inlet challenge before reaching the 5ppm limit on the outlet. Other tests showed that using air with a dewpoint of -40°C, (-40°F) did gradually improve the performance of the catalyst, as the water vapour was slowly desorbed over time. So in conclusion to avoid growth of micro-organisms, a dew point better than -26ºC, (-15ºF) is required and ideal is a dew point of -40°C, (-40°F) or better for increased granular filter performance and life within compressed air systems for medical air.

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Can one use Refrigerant Dryers with Medical Air?

We would not recommend at any time to do so, as it is almost impossible to comply with the international medical air quality standards.


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