At, we do our best to use standardized nomenclature to describe our products. Frequently we also use abbreviations to describe product details. If the terminologies and/or abbreviations used on this site are confusing or unclear, we hope this glossary of acronyms, abbreviations and terms will help. Glossary of Acronyms, Abbreviations and Terms

~ Tilde Sign: Used to indicate an estimate, i.e. ~7 min =  approximately 7 minutes
± Plus-Minus Sign: Indicates the precision of an approximation, i.e. ±5°F = plus or minus 5 degrees Fahrenheit
< Less Than Sign
Less Than or Equal To Sign
> Greater Than Sign
Greater Than or Equal To Sign
' Apostrophe: Foot/Feet, i.e. 5'
" Quotation Mark: Inch/Inches, i.e. 11"
° Degree Sign (angle or temperature)
A Amperage. Also abbreviated as "amp."
Å Angstrom or ångström.
CFM Actual Cubic Feet per Minute. See "Fill Time (CFM/ACFM)."
amp Amperage. Also abbreviated as "A."
Angstrom A measure of distance equal to 10−10 m (one ten-billionth of a meter or 0.1 nanometers). Also abbreviated as "Å."
Ar Argon
ata Atmospheres Absolute. In diving, it is the total ambient pressure at depth including atmospheric pressure. 10 m (33 ft) of sea water = 14.7 psi.
atm Atmosphere. 1 atm = 1.01325 bar. 1 atm = 14.7 psi. Refers to the weight (pressure) of the earth's atmosphere at sea level.
bar Metric Unit of Pressure (1 bar = 14.5 psi)
C Centigrade (Metric)
cc/min Cubic Centimeters per Minute
cd/m² One candela per square meter. A "candela" is the SI unit of luminous intensity.
CFM Cubic Feet per Minute. See "Fill Time (CFM/ACFM)."
CGA The Compressed Gas Association, an ANSI-accredited standards developing organization, is the publisher of the seventh edition of CGA G-7.1-2018: Commodity Specification for Air. This standard addresses the large variety of trace constituents in air. It would be impractical to set individual limits for many of these, but the specification establishes certain grades of air by limiting the concentrations of specific trace constituents. The different quality verification levels (QVLs) for carbon dioxide, carbon monoxide, nitric acid, nitrogen dioxide, nitrous oxide, odor, and other limiting characteristics are classified by component maxima in parts per million (ppm [v/v]). CGA G-7.1-2018 provides the means to classify grades (at A, L, D, E, J, and N) of QVLs. Each grade corresponds with a typical usage. For example, CGA grade A is typically industrial compressed air and grade D is OSHA breathing air. CGA G-7.1-2018 also includes information on quality verification systems, containers, moisture conversion data, and analytical procedures for water carbon dioxide, odor, and other characteristic content.
Charging Rate The rate at which a compressor fills a tank/cylinder. Usually expressed in CFM/ACFM, SCFM and L/min.
cm Centimeter/Centimeters
CO Carbon Monoxide
CO2 or CO2 Carbon Dioxide
cSt Centistrokes
cu in Cubic Inches
cu ft Cubic Feet
Cv Valve Flow Coefficient
dB Decibels
DIN German Institute for Standardization (Deutsche Institut für Normung e.V.)
DIN 200 American reference to a 232 bar DIN valve.
DIN 232 A 5-thread 232 bar DIN valve. 
DIN 300 A 7-thread 300 bar DIN valve most commonly used in Europe. 
DIN Rail A standardized metal rail used to mount electrical components inside of equipment racks. DIN rails are used in some Nuvair equipment.
dm³/s Cubic decimeter per second. 1 dm³/s = 0.4719 CFM.
E1 Single Phase [electrical power]
E3 Three Phase [electrical power]
EAN or EANx Enriched Air Nitrox
EANx32, EANx36, etc. Enriched Air Nitrox, i.e. EANx40 = 40% oxygen
EN European Standard
EN 12021 Refers to the European Standard on "Respiratory equipement. Compressed gases for breathing apparatus." There are two sources for this information: BS EN 12021:2014 and DIN EN 12021.
F Fahrenheit (Imperial)
FAD Free Air Delivery
Fill Time (CFM/ACFM) Fill time based on filling an 80 cu ft tank from 0 to 3000 psi. (Calculation: 80 ÷ CFM/ACFM Rate = CFM/ACFM Fill Time)
Fill Time (SCFM) Fill time based on filling an 80 cu ft cylinder from 500 to 3000 psi. (Calculation: 80 ÷ SCFM Rate x 0.8333 = SCFM Fill Time)
FNPT Female National Pipe Thread
ft Foot/Feet
g Gram/Grams
g/L Grams per Liter
gal Gallon/Gallons
Grade D Frequently referred to as "CGA Grade D" air, it is one of two popular standards of breathing air quality established by the Compressed Gas Association (CGA). Specifcations for CGA Grade D (2011) air are identified by Lawrence-Factor® X-zam® analysis specifications (SKU LS-901070):

• Oxygen (%):  19.5 - 23.5
• Carbon Dioxide (ppm): 1000
• Carbon Monoxide (ppm): 10
• Water Vapor (ppm): 67 - may vary with intended use
• Dew Point (F): -50
• Oil & Particles (mg/m³): 5
• Odor: None
Grade E Frequently referred to as "CGA Grade E" air, it is one of two popular standards of breathing air quality established by the Compressed Gas Association (CGA). Specifcations for CGA Grade E (2011) air are identified by Lawrence-Factor® X-zam® analysis specifications (SKU LS-901171):

• Oxygen (%): 20 - 22
• Carbon Dioxide (ppm): 1000
• Carbon Monoxide (ppm): 10
• Hydrocarbons (ppm): 25
• Oil & Particles (mg/m³): 5
• Odor: None
H2S Hydrogen Sulfide
He Helium
hp Horsepower
Hz Hertz
ICFM Inlet Cubic Feet per Minute
I.D. or ID Inner (interior) diameter of a tube, pipe, or hose
in Inch/Inches
inHg Inches of Mercury (vacuum)
ISO International Organization for Standardization
kg Kilograms
kgf/cm² Kilogram-force per square centimeter 
kW Kilowatt
L Liter/Liters (Litre)
L x W x H Dimensions of a Product: Length x Width x Height
L/min Liters per Minute
LpA or LPA An estimation of A-weighted machinery sound pressure levels at the operator's position, expressed in decibels (dB). 
lb Pound/Pounds [Weight]
m Meter/Meters (Metre)
m³/h Cubic Meters per Hour [gas flow rate]. See also nm³/h.
mA Milliamp
mAh Milliamp Hours
micromenter 1/1,000,000th of a meter. 1 x 10-6m. Also referenced as micron or μm
micron See "micrometer"
min Minute/Minutes
mL Milliliter/Milliliters
mm Millimeter/Millimeters
MNPT Male National Pipe Thread
mV Millivolt/Millivolts
N2 or N2 Nitrogen
NFPA® National Fire Protection Association
NFPA 1500 NFPA 1500™ specifies the minimum requirements for an occupational safety and health program for fire departments or organizations that provide rescue, fire suppression, emergency medical services, hazardous materials mitigation, special operations, and other emergency services.
Nitrox A gas mixture of nitrogen (N2) and oxygen (O2). Also referred to as: Enriched Air Oxygen, Oxygen Enriched Air, EAN, and EANx.
nits A measurement of computer display luminance. See cd/m².
nm³/h Normal Cubic Meters per Hour [gas flow rate]. "Normal" in this context is conditions of 0°C and 1 atm (1 bar). See also m³/h.
O2 or O2 Oxygen
OCA Oxygen Compatible Air
O.D. or OD Outer diameter of a tube, pipe, or hose
oz Ounce/Ounces in Volume or Weight
PNEUROP European association of manufacturers of compressors, vacuum pumps, pneumatic tools and air & condensate treatment equipment
ppm Parts per Million
psi Pounds per Square Inch: Imperial Unit of Pressure (100 psi = 6.89 bar)
qt Quart/Quarts
rh Relative Humidity
RoHS Restriction of Hazardous Substances
RPM Revolutions per Minute
SCBA Self-Contained Breathing Apparatus
SCFM Standard Cubic Feet per Minute. See "Fill Time (SCFM)."
SCUBA or scuba Self-Contained Underwater Breathing Apparatus
SKU Stock Keeping Unit: Used as Nuvair's product identification number (part number)
μm See "micrometer"
V Volt
VAC Volts of alternating current
VDC Volts of direct current

Volatile organic compounds (VOC) means any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate, which participates in atmospheric photochemical reactions. (1) This includes any such organic compound other than the following, which have been determined to have negligible photochemical reactivity: Methane; ethane; methylene chloride (dichloromethane); 1,1,1-trichloroethane (methyl chloroform); 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113); trichlorofluoromethane (CFC-11); dichlorodifluoromethane (CFC-12); chlorodifluoromethane (HCFC-22); trifluoromethane (HFC-23); 1,2-dichloro 1,1,2,2-tetrafluoroethane (CFC-114); chloropentafluoroethane (CFC-115); 1,1,1-trifluoro 2,2-dichloroethane (HCFC-123); 1,1,1,2-tetrafluoroethane (HFC-134a); 1,1-dichloro 1-fluoroethane (HCFC-141b); 1-chloro 1,1-difluoroethane (HCFC-142b); 2-chloro-1,1,1,2-tetrafluoroethane (HCFC-124); pentafluoroethane (HFC-125); 1,1,2,2-tetrafluoroethane (HFC-134); 1,1,1-trifluoroethane (HFC-143a); 1,1-difluoroethane (HFC-152a); parachlorobenzotrifluoride (PCBTF); cyclic, branched, or linear completely methylated siloxanes; acetone; perchloroethylene (tetrachloroethylene); 3,3-dichloro-1,1,1,2,2-pentafluoropropane (HCFC-225ca); 1,3-dichloro-1,1,2,2,3-pentafluoropropane (HCFC-225cb); 1,1,1,2,3,4,4,5,5,5-decafluoropentane (HFC 43-10mee); difluoromethane (HFC-32); ethylfluoride (HFC-161); 1,1,1,3,3,3-hexafluoropropane (HFC-236fa); 1,1,2,2,3-pentafluoropropane (HFC-245ca); 1,1,2,3,3-pentafluoropropane (HFC-245ea); 1,1,1,2,3-pentafluoropropane (HFC-245eb); 1,1,1,3,3-pentafluoropropane (HFC-245fa); 1,1,1,2,3,3-hexafluoropropane (HFC-236ea); 1,1,1,3,3-pentafluorobutane (HFC-365mfc); chlorofluoromethane (HCFC-31); 1 chloro-1-fluoroethane (HCFC-151a); 1,2-dichloro-1,1,2-trifluoroethane (HCFC-123a); 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane (C4F9OCH3 or HFE-7100); 2-(difluoromethoxymethyl)-1,1,1,2,3,3,3-heptafluoropropane ((CF3)2OCH3); 1-ethoxy-1,1,2,2,3,3,4,4,4-nonafluorobutane (C4F9OC2H5 or HFE-7200); 2-(ethoxydifluoromethyl)-1,1,1,2,3,3,3-heptafluoropropane ((CF3)2CFCF2OC2H5); methyl acetate; 1,1,1,2,2,3,3-heptafluoro-3-methoxy-propane (n-C3F7OCH3, HFE-7000); 3-ethoxy- 1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-(trifluoromethyl) hexane (HFE-7500); 1,1,1,2,3,3,3-heptafluoropropane (HFC 227ea); methyl formate (HCOOCH3); 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-trifluoromethyl-pentane (HFE-7300); propylene carbonate; dimethyl carbonate; trans-1,3,3,3-tetrafluoropropene; HCF2OCF2H (HFE-134); HCF2OCF2OCF2H (HFE-236cal2); HCF2OCF2CF2OCF2H (HFE-338pcc13); HCF2OCF2OCF2CF2OCF2H (H-Galden 1040x or H-Galden ZT 130 (or 150 or 180)); trans 1-chloro-3,3,3-trifluoroprop-1-ene; 2,3,3,3-tetrafluoropropene; 2-amino-2-methyl-1-propanol; t-butyl acetate; 1,1,2,2- Tetrafluoro -1-(2,2,2-trifluoroethoxy) ethane; cis-1,1,1,4,4,4-hexafluorobut-2-ene (HFO-1336mzz-Z); and perfluorocarbon compounds which fall into these classes:

(i) Cyclic, branched, or linear, completely fluorinated alkanes;

(ii) Cyclic, branched, or linear, completely fluorinated ethers with no unsaturations;

(iii) Cyclic, branched, or linear, completely fluorinated tertiary amines with no unsaturations; and

(iv) Sulfur containing perfluorocarbons with no unsaturations and with sulfur bonds only to carbon and fluorine.

[source: 40 CFR Part 51.100(s)]

Volatile organic compounds (VOC) are emitted as gases from certain solids or liquids. VOCs include a variety of chemicals, some of which may have short- and long-term adverse health effects. Concentrations of many VOCs are consistently higher indoors (up to ten times higher) than outdoors. VOCs are emitted by a wide array of products numbering in the thousands. Organic chemicals are widely used as ingredients in household products. Paints, varnishes and wax all contain organic solvents, as do many cleaning, disinfecting, cosmetic, degreasing and hobby products. Fuels are made up of organic chemicals. All of these products can release organic compounds while you are using them, and, to some degree, when they are stored. [source: EPA]

Wh Watt-Hour
Zero Air Specially polished Grade E air that contains less than 0.1 ppm of hydrocarbon impurities.