Glossary “Refrigerant HCFC-22 (R-22)” Definition:
A refrigerant, monochlorodifluoromethane (CHC1F2), used in some early automotive applications but not to be used for today’s automotive air conditioners because of high pressures.
r
Refrigerant HFC-134a (R-134a)
Glossary “Refrigerant HFC-134a (R-134a)” Definition:
The “refrigerant of choice,” tetrafluoroethane (CH2FCF3), to be used in automotive air conditioners as R-12 is being phased out.
refractometer
Glossary “refractometer” Definition:
Instrument used to measure substances dissolved in water and certain oils. It works on the principle of light refraction through liquids. As light passes from air into a liquid it slows down and this phenomenon is what gives a “bent” look to objects that are partially submerged in water. Refactometers use this principle to determine the amount of dissolved solids in a liquid by passing light through a sample and showing the refracted angle on a scale. In automotive applications, reflactometers are used to measure the specific gravity of battery electrolyte and antifreeze concentrations.
refrigerant
Glossary “refrigerant” Definition:
Chemical compound used in a refrigeration system to produce the desired cooling effect.
refinishing materials
Glossary “refinishing materials” Definition:
General term used to refer to the products used to repaint or refinish a vehicle.
refl
Glossary “refl” Definition:
Acronym form of Reflector.
reformer
Glossary “reformer” Definition:
Device that extracts pure hydrogen from hydrocarbons.
reformulated gasoline (RFG)
Glossary “reformulated gasoline (RFG)” Definition:
Gasolines which have had their composition and/or characteristics altered to reduce vehicular emissions of pollutants. Specifically, those gasolines which meet the RFG requirements of the 1990 Clean Air Act Amendments.
refraction
Glossary “refraction” Definition:
The breakup of a light beam into its component parts. In sunlight, light rays include all the colors in a rainbow.
reference points
Glossary “reference points” Definition:
Identifiable points on a vehicle that may be used for measurements when a control point is not available.
reference voltage
Glossary “reference voltage” Definition:
Usually a five-volt signal sent out from the electronic control unit to a variable-resistance sensor such as a throttle-position sensor. As the sensor changes, due operating conditions, the return voltage is altered and sent back to the computer as a signal for use by the microprocessor.
refinish
Glossary “refinish” Definition:
The replacement of undercoat and top color coat; the complete finish of a spot, large area, panel, or complete vehicle.
reed valve
Glossary “reed valve” Definition:
1). A thin leaf of steel located in the valve plate of automotive compressors, serving as suction and discharge valves. 2). Used to control exhaust backpressure in a pulse AIR systems.
reed tachometer
Glossary “reed tachometer” Definition:
Tool that consists of several metal reeds. Each reed is tuned to react to a different frequency. It is used to measure the frequency of a vibrating component.
redundant system
Glossary “redundant system” Definition:
Duplicated system; a secondary or backup system.
reduction reaction
Glossary “reduction reaction” Definition:
Chemical reaction in which electrons are removed from a compound, such as when oxygen is removed from compound.
redundant
Glossary “redundant” Definition:
Duplication; a secondary or backup system.
redundant brake shutoff
Glossary “redundant brake shutoff” Definition:
Safety feature of speed control systems that shut the speed control off if there is a 10-15 mph drop in speed.
reducing flame
Glossary “reducing flame” Definition:
An oxyfuel gas flame with an excess of fuel gas.
reduction
Glossary “reduction” Definition:
See under drive.