Meh Flashcards
Types of valves and what they do and effects on fluids
Filter definitions
ASHRAE VS AHRI VS ABSA VS…
CSA & ABSA: B52-05
ASHRAE: flammability, toxicity,
Alberta Environment: administration of the Code of Practice
AHRI: determines refrigerant GWPs
National Office of Pollution 1996: Code of Practice
Number meaning in Refrigeration numbers 🦀
Entropy units
BTU/lb °R
Temp rise, temp difference
(∆T) Temp rise/drop -> SST/SDT & ambient
(TD) Temp difference (diff mediums) -> ambient & cond/evap
Def of work
Force * distance
HCFCs, HFCs, HFOs, etc
HFOs: (new), r1234y,
HFCs: r23, r32, r134a, r404a, r410a, etc
HCFCs: r22, r123, r124,
CFCs: r12, 13,
Spill vs rollout
Spill: interrupts the heating control circuit due to backdraft (hot flue gases spill out of the flue hood)
Rollout: Interrupts the heating cycle due to rollout (burner flame and flue gases remain the the burner compartment instead of heat exchanger)
Forward curved vs backwards vs axial curved noise
Forward: quiet
Backwards:
Axial: noisy
Flat blade
Medium air flow, low static pressure
Curved airfoil
High airflow, high static pressure
Radial tip
High air flow, medium static pressure
400CFM/ton for ACs and 450CFM/ton for heat pumps
1ton = 700sqft
PRV vs pressure relief vs pressure reducing, blowdown
PRV (pressure reducing valve) : limits the pressure for branch pressure use
Pressure relief valve: safety
Blowdown valve: Remove condensation from the receiver
Pressure controller: Starts and stops the motor to maintain receiver pressure
Spring range
The range to produce total movement from one extreme position to another
Pump down
Pump out
Pump down used on large built-up medium temp walk in coolers cuz of long lines
Pump out used on larger low temp to reduce short cycling
Primary controller/control
Directly/indirectly controls the control agent
Deviation
Offset
Deviation: length of time for control point and setpoint to equalize
or Difference between control point and setpoint at any instant
Offset: Sustained difference between control point and setpoint
Line duty vs pilot duty
Line duty: interrupts the CURRENT directly to the motor
Pilot duty: interrupts a relay or something CURRENT that stops the motor
Controlled device
Actuator/final control element/valve
Controlled variable
Manipulated variable
Measured variable
Quantity or condition of the controlled medium
Quantity or condition of the control agent
Range
Span
Difference between least and greatest values of a controller
Difference between two limits
Sulphur, regulator places names, specific density/volume,
Pipe controller output to actuator vs input sensor pressure
Output to actuator: 0-20psi
Input from sensor: 3-15psi
remote bulbs are found in contact with _
controlled medium
Usual NON ADJUSTABLE High limit setpoint
HL: 180F-220F
Combination fan limit controller cut in and cut out temps
Cut out: 80-90F
Cut in: 120-140F
Low ambient limit controller temperature
50F (same as changeover temp 50-60F)
Furnace limit controls
Usual ADJUSTABLE high limit
HL: 150-200F
Burnt open vs shorted
Shorted: over current
Resistance, inductance, capacitance, reactance, impedance opposes what
Impedance: total opposition to flow of current
Resistance: Limits amount of current
Inductance: opposes change in current
Capacitance: opposes change in voltage
Reactance:
Fuses protect
Conductor
Air permeability
Air escaping from building
6-10 duct diameter
30° TD
Hydrometer
Schedules/specification book, section|page number
Vernier
