Helpful Definitions for Breathing Air System Terminology
ACTIVATED CHARCOAL (Carbon) |
A porous substance generally capable of absorbing odors and molecules of organic substances from gases and liquids. It is commonly used in air filtration. |
AUTOMATIC CONDENSATE DRAIN (A.C.D.) |
By means of one or more electric timers, a solenoid valve momentarily drains each of the systems separators, automatically, of accumulated liquid; usually every 15-18 minutes of operation without the operator must manually perform this function. Most serious manufacturers will set the timers to drain periodically and on SHUT DOWN, assuring that the entire system is moisture free during down time and will re-start without load. |
| ADSORPTION | The adhesion (in any extremely thin layer) of molecules of gases or liquids to the surface of a solid, such as a container, causing a greater concentration on that surface. |
AFTERCOOLER |
A heat exchanger, installed in a compressor system following the final stage, for the extraction of heat from the compressed air stream. |
ATMOSPHERE |
Pressure unit equal to 14.7 psi |
BAR |
Barometric pressure unit equal to 14.7 psi |
CARBON DIOXIDE (CO2) |
Classed as a toxic gas. Less dangerous than CO. Concentration of more than 10% may be tolerated for a short period. |
CARBON MONOXIDE (CO) |
One of the deadliest of the toxic gases. Small amounts will cause adverse reactions. Danger increased by the fact that it is both odorless and tasteless. |
CATALYST |
A chemical used to initiate the conversion of carbon monoxide to carbon dioxide in a respiratory air purification system (Hopcalite). |
CFM (Cubic Feet Per Minute) |
A measurement of air flowing through a given point in one minute. |
CONTAMINANT |
A solid or gaseous substance which may cause harmful impurity or pollution. |
DEHYDRATION |
Is the removal of water from an air purification system. This is usually done in two phases which are:
|
DESICCANT |
A chemical capable of absorbing contaminant gases, aerosols and water vapor. |
DEW POINT |
The variable temperature at which water vapor begins to condense as a liquid at atmospheric pressure. This term is used to denote the presence of moisture content in the air. |
DISPLACEMENT |
The volume of air displaced by a full stroke of the first stage piston, multiplied by the rated RPM of the compressor. This is measured in cubic feet per minute (CFM). |
F.A.D. (Free Air Delivery) |
The volume of air which is drawn in from the atmosphere by the compressor, then compressed and delivered at a specific rate of pressure. |
FILTRATION |
Filtration rating/de-rating based on 72oF ambient temperature. If your filter is rated for 10,000 cft @ 72oF, draining the condensate often, you must de-rate the 10,000 cft by 2% for every 1oF above 72oF. The reverse applies for temperature below 72oF. |
FILTRATION RATING |
Usually stated in terms of “absolute” or “normal”.
|
HYDROCARBONS |
Any compound containing only hydrogen and carbon. |
INTERCOOLER |
A heat exchanger, usually air cooled, installed between stages of a compressor to cool the gases. This reduces the volume and increases the efficiency of the succeeding stage. |
MICRON |
A unit of measurement referring to the dimensions of very small particles and hence used in the rating of filters. One micron is equivalent to one millionth of one meter; one thousandth of one millimeter; or approximately 0.00004 of an inch. |
MOLECULAR SIEVE |
A high grade crystalline alumino silicate used as an absorbent. It has excellent drying properties and is valuable in the removal of water and oil vapors from air and gases (molecular sieve 13X). |
PRESSURE MAINTAINING VALVE (P.M.V.) aka BACK PRESSURE VALVE |
Typically employed to maintain constant pressure on the filter system. Thereby, increasing efficiency of the purification process for optimum air processing and prolonged cycle life. |
PSI (Pounds Per Square Inch) |
An expression used in the measurement of air pressure. |
PSIG (Pounds Per Square Inch-Gauge) |
This measurement of air pressure does not include atmospheric pressure and starts at 14.7 psi. |
| SCFM (Standard Cubic Feet Per Minute) | A measurement of air flow corrected to standard conditions used by all compressor manufacturers except one. The world standard refers to filling an 80 cubic foot cylinder from 0~2800 psig. The other system refers to SCFM in the filling of that cylinder from 500~3000 psig. This assumes that all cylinders have 500 psig residual pressure. |
