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Compressed Air Glossary of Terms :: H ::
Glossary Index
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- Head adiabatic
- The energy in foot pounds required to compress adiabatically
and to deliver one pound of a given gas from one pressure level to
another.
- Header
- The main distribution pipe.
- Head polytropic
- The energy in foot pounds required to compress polytropically
and to transfer one pound of a given gas from one pressure level
to another.
- Head pressure
- A term used to describe the hot gas pressure on the outlet
side of the refrigeration compression.
- Heat exchanger
- Is used to cool compressed air or gas. Designed to reduce the
temperature and liquefy condensate vapors.
- Heatless dryer
- Heatless reactivated dryer. By means of expanding cold dry air
to near atmospheric pressure inside the regeneration tower, the
dryer air picks up moisture from the saturated desiccant bed and
is then purged to atmosphere.
- Heat reactivated
dryers
- Are categorized as internal or external heat reactivated.
Internal type - Process air enters the dryer through the
inlet piping, is then dried as it passes through the desiccant
bed, and discharges through the outlet piping as dry air.
Regeneration of the desiccant is accomplished at atmospheric
pressure, using steam or electric heaters, embedded in the
desiccant bed. External type - Process air enters the
dryer through the inlet piping, is then dried as it passes through
the desiccant bed, and discharges through the outlet piping as dry
air. Reactivation is accomplished using a reactivation blower or a
cooler.
- Heat recovery
- Recovering and utilizing the heat content of the compressed
air.
- High efficiency
filtration
- The unofficial filtration industry description for filters
designed to trap small size contaminants.
- High volume low
pressure
- In spray painting applications, Spray equipment which delivers
material at a low pressure of no more than 10 PSI (at the air
cap), however, with greater volume of air.
- Horsepower (HP)
- Is a unit of work equal to 33,000 foot pounds per minute, 550
foot pounds per second, or 746 Watts.
- Horsepower brake
(BHP)
- The horsepower input to the compressor shaft, or more
generally to any driven machine shaft.
- Horsepower gas
- The actual work required to compress and deliver a given gas
quantity, including all thermodynamic, leakage and fluid friction
losses. It does not include mechanical losses.
- Horsepower ideal
- The horsepower required to isothermally compress the air or
gas delivered by the compressor at specified conditions.
- Horsepower indicated
- The horsepower calculated from compressor-indicator diagrams.
Applied only to displacement type compressors.
- Horsepower peak
- The maximum power required by a given compressor when
operating at a (1) constant discharge pressure with variable
intake pressure, or (2) constant intake pressure with variable
discharge pressure.
- Horsepower
theoretical
- The horsepower required to compress adiabatically the air or
gas delivered by the compressor through the specified range of
pressures.
- Hot gas
- A term applied to the gas found on the high pressure side of
the refrigeration system.
- Hot gas bypass valve
- A valve which connects the high pressure side of a compressed
air system to the suction side and is adjusted so as to maintain a
specific pressure on the suction side by controlled bleeding of
hot gas to the suction side.
- Hot start
- The compressor is started automatically, depending on demand.
Control panel is energized with no "pre-start" cycle required, as
pre-lubrication pump and buffer (seal) air are always "on". A
state of pre-start exists. Steam turbine compressors are
"slow-rolling" to maintain "pre-start" turbine temperatures at an
adequate, recommended level. "Heavy" instrumentation and
monitoring accessories are recommended.
- Housing
- A ported enclosure which directs the flow of a gas through the
filter element.
- Humidity
- The moisture content of air.
- Humidity specific
- The weight of water vapor in the air vapor mixture per pound
of dry air.
- Humidity relative
- The relative humidity of a gas (or air) vapor mixture is the
ratio of the partial pressure of the vapor to the vapor saturation
pressure at the dry bulb temperature of the mixture.
- HVLP
- In spray painting applications, spray equipment which delivers
material at a low pressure of no more than 10 PSI (at the air
cap), however, with greater volume of air.
- Hydrocarbons
- Chemicals containing carbon and hydrogen.
- Hydrogen
chlorofluorocarbons (HCFC)
- Chemical species slated to replace CFCs in the near future.
- Hygroscopic cells
- Are any material with an affinity for moisture. These
analyzers use sensing elements that contain moisture adsorbing
material. A change in the moisture content of the element is
detected by an electric network and is used as a measurement of
dew point
Glossary Index
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
Thanks to Impact RM for permission to reprint the glossary.
Compressed Air Glossary © Impact RM
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