Editing Compressor (section)

====Rotary screw compressors====

[[File:RotaryScrewCompressor.gif|thumb|a Diagram of a rotary screw compressor|alt=www]]
{{main|Rotary screw compressor}}
'''Rotary screw compressors''' use two meshed rotating positive-displacement [[Helix|helical screws]] to force the gas into a smaller space.<ref name=Perry/><ref>[http://www.blackmer.com/tech-screw.jsp Screw Compressor] {{webarchive|url=https://web.archive.org/web/20080110103341/http://www.blackmer.com/tech-screw.jsp |date=2008-01-10 }} Describes how screw compressors work and include photographs.</ref><ref>[http://www.domnickhunter.com/tech_Centre.asp?chapter=1&section=3_Screw-Compressors_2_3.htm&getIndex=false Technical Centre] {{webarchive|url=https://web.archive.org/web/20071213211548/http://www.domnickhunter.com/tech_Centre.asp?chapter=1&section=3_Screw-Compressors_2_3.htm&getIndex=false |date=2007-12-13 }} Discusses oil-flooded screw compressors including a complete system flow diagram</ref> These are usually used for continuous operation in commercial and industrial applications and may be either stationary or portable. Their application can be from {{convert|3|hp|kW}} to over {{convert|1200|hp|kW}} and from low pressure to moderately high pressure (>{{convert|1200|psi|MPa|1|abbr=on|disp=or}}).

The classifications of rotary screw compressors vary based on stages, cooling methods, and drive types among others.<ref>{{Cite news|url=http://www.industrialcompressorsolutions.com/articles/how-does-a-rotary-screw-air-compressor-work|title=How Does a Rotary Screw Air Compressor Work?|last=ICS|access-date=2017-08-16|language=en|url-status=live|archive-url=https://web.archive.org/web/20170817001135/http://www.industrialcompressorsolutions.com/articles/how-does-a-rotary-screw-air-compressor-work|archive-date=2017-08-17}}</ref> Rotary screw compressors are commercially produced in Oil Flooded, Water Flooded and Dry type. The efficiency of rotary compressors depends on the air drier,{{clarify|date=May 2014}} and the selection of air drier is always 1.5 times volumetric delivery of the compressor.<ref>{{Cite book|url=https://books.google.com/books?id=1w5yBgAAQBAJ&q=%22The+efficiency+of+rotary+compressors+depends+on+the+air+drier%22&pg=PA643|title=Hydraulic Fracturing Operations: Handbook of Environmental Management Practices|last1=Cheremisinoff|first1=Nicholas P.|last2=Davletshin|first2=Anton|date=2015-01-28|publisher=John Wiley & Sons|isbn=9781119100003|language=en|url-status=live|archive-url=https://web.archive.org/web/20171224222642/https://books.google.com/books?id=1w5yBgAAQBAJ&pg=PA643&lpg=PA643&dq=%22The+efficiency+of+rotary+compressors+depends+on+the+air+drier%22&source=bl&ots=DIZJEjhMaW&sig=coZe1GEy2bN8CTUmSaK8IuA3jSw&hl=en&sa=X&ved=0ahUKEwjV9YOjntzVAhUp7oMKHeIvCLoQ6AEILDAB#v=onepage&q=%22The%20efficiency%20of%20rotary%20compressors%20depends%20on%20the%20air%20drier%22&f=false|archive-date=2017-12-24}}</ref>

Designs with a single screw<ref>{{cite web|url=https://www.daikinapplied.uk/features/single-screw-compressor |title=Single Screw Compressor |website=Daikin Applied UK}}</ref> or three screws<ref>{{citation|url=http://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2824&context=icec |last=Jacobs |first=John S. |title=Variable Speed Tri-Rotor Screw Compression Technology |date=2006 |publisher=International Compressor Engineering Conference. Paper 1825.}}</ref> instead of two exist.

Screw compressors have fewer moving components, larger capacity, less vibration and surging, can operate at variable speeds, and typically have higher efficiency. Small sizes or low rotor speeds are not practical due to inherent leaks caused by clearance between the compression cavities or screws and compressor housing.<ref name=autogenerated1 /> They depend on fine machining tolerances to avoid high leakage losses and are prone to damage if operated incorrectly or poorly serviced.