California CSLB C-38 Refrigeration Examination

A walk-in cooler load calculation requires calculating sensible heat gain from outdoor ventilation air. If 200 CFM of outdoor air at 95 degrees F dry-bulb enters a walk-in cooler maintained at 35 degrees F, what is the sensible heat load in BTU/hr?

• A12,960 BTU/hr sensible heat load.
• B15,480 BTU/hr sensible heat load.
• C10,800 BTU/hr sensible heat load.
• D18,200 BTU/hr sensible heat load.

A commercial freezer wall has an overall heat transfer coefficient (U-factor) of 0.035 BTU/hr-sq ft-degree F and a surface area of 400 sq ft. If the ambient design temperature is 90 degrees F and the freezer interior is -10 degrees F, what is the wall heat transmission load?

• A1,120 BTU/hr total wall transmission heat load.
• B1,400 BTU/hr total wall transmission heat load.
• C1,680 BTU/hr total wall transmission heat load.
• D2,100 BTU/hr total wall transmission heat load.

A refrigeration contractor must estimate the product load to cool 2,000 lbs of fresh beef from 65 degrees F down to 35 degrees F over a 24-hour pull-down period. Given the specific heat above freezing is 0.75 BTU/lb-degree F, what is the required hourly product cooling load?

• A1,250 BTU/hr required hourly cooling load.
• B1,500 BTU/hr required hourly cooling load.
• C1,875 BTU/hr required hourly cooling load.
• D2,250 BTU/hr required hourly cooling load.

When estimating compressor operating conditions for an R-404A low-temperature system, suction pressure is 15.3 psig and discharge pressure is 235.3 psig. What is the absolute compression ratio of the system?

• A15.38:1 absolute compressor pressure ratio.
• B12.50:1 absolute compressor pressure ratio.
• C10.25:1 absolute compressor pressure ratio.
• D8.33:1 absolute compressor pressure ratio.

According to standard commercial refrigeration piping guidelines, what minimum suction line refrigerant velocity must be maintained in vertical risers during minimum system load capacity to ensure proper oil return to the compressor?

• A1,500 feet per minute minimum line velocity.
• B2,500 feet per minute minimum line velocity.
• C3,500 feet per minute minimum line velocity.
• D4,500 feet per minute minimum line velocity.

In commercial refrigeration system planning, what is the maximum recommended total equivalent pressure drop in liquid lines, expressed in terms of saturation temperature change?

• A0.5 degree Fahrenheit saturation drop.
• B1 to 2 degrees Fahrenheit saturation drop.
• C5 to 6 degrees Fahrenheit saturation drop.
• D8 to 10 degrees Fahrenheit saturation drop.

When planning the electrical branch circuit wire size for a hermetic motor-compressor with a rated-load current (RLC) of 24 amperes, what minimum conductor ampacity must be specified under California Electrical Code standards?

• A24 amperes minimum conductor ampacity.
• B27 amperes minimum conductor ampacity.
• C30 amperes minimum conductor ampacity.
• D36 amperes minimum conductor ampacity.

Under California Electrical Code rules, what maximum standard percentage rating of rated-load current is initially permitted for the continuous overcurrent protective device (OCPD) on a motor-compressor branch circuit?

• A115 percent of rated load current value.
• B125 percent of rated load current value.
• C150 percent of rated load current value.
• D175 percent of rated load current value.

According to California Mechanical Code (CMC Chapter 11), what formula determines the required mechanical emergency exhaust ventilation rate Q in CFM for a machinery room containing a total refrigerant charge M of 400 lbs?

• A2,000 CFM required exhaust ventilation rate.
• B4,000 CFM required exhaust ventilation rate.
• C6,000 CFM required exhaust ventilation rate.
• D8,000 CFM required exhaust ventilation rate.

When estimating piping materials for a commercial refrigeration machinery room, which copper pipe classification is required by California Mechanical Code Chapter 11 for exposed suction lines?

• AType M seamless drawn hard copper tubing.
• BType L seamless drawn hard copper tubing.
• CType DWV seamless drawn hard copper pipe.
• DClass 125 threaded galvanized steel pipe.

A low-temperature evaporator coil requires electric defrost heaters rated to deliver 12,000 BTU/hr during defrost. Converting BTU/hr to electrical power, what total heater capacity in kilowatts (kW) must be estimated?

• A2.50 kW total electric defrost capacity.
• B3.00 kW total electric defrost capacity.
• C3.52 kW total electric defrost capacity.
• D4.10 kW total electric defrost capacity.

When selecting a Thermostatic Expansion Valve (TXV) for an R-134a medium-temperature system operating at 30 degrees F evaporating temp (26.1 psig) and 110 degrees F condensing temp (146.4 psig), what is the pressure drop across the valve?

• A85.2 psi net pressure drop across valve.
• B96.4 psi net pressure drop across valve.
• C108.1 psi net pressure drop across valve.
• D120.3 psi net pressure drop across valve.

Per California Mechanical Code Chapter 11, machinery rooms containing Group A1 or B2L refrigerants must have tight-fitting exit doors that open in which direction and feature what closing mechanism?

• AOutward opening with self-closing hardware.
• BInward opening with self-closing hardware only.
• CSliding design with manual latching lock.
• DDouble acting with standard lever handles.

When estimating liquid line sizing for an R-410A system with a vertical liquid riser of 40 feet, how much static pressure head loss occurs due to vertical height (R-410A liquid density approx 0.46 psi/ft rise)?

• A12.2 psi static pressure drop in riser.
• B18.4 psi static pressure drop in riser.
• C24.6 psi static pressure drop in riser.
• D30.8 psi static pressure drop in riser.

On a commercial refrigeration mechanical drawing (P&ID), what standard graphic symbol identifies a pilot-operated solenoid valve installed in a hot-gas line?

• AA square block with an internal check valve mark.
• BA circle with a vertical line and shaded triangle only.
• CAn envelope valve symbol topped with an electric coil.
• DA diamond enclosure containing a pressure gauge.

When planning a commercial supermarket parallel rack system, the high-pressure liquid receiver should be sized to hold what percentage of the total system operating charge under full pump-down conditions?

• A50 percent maximum operating liquid volume.
• B65 percent maximum operating liquid volume.
• C75 percent maximum operating liquid volume.
• D90 percent maximum operating liquid volume.

When estimating labor for installing a multi-evaporator rack suction manifold, a contractor counts 24 hard-drawn copper joints. If average labor productivity is 15 minutes per joint including nitrogen purging, how many total man-hours are estimated?

• A6.0 man-hours total estimated piping labor.
• B8.0 man-hours total estimated piping labor.
• C10.0 man-hours total estimated piping labor.
• D12.0 man-hours total estimated piping labor.

A commercial planning specification calls for an aqueous propylene glycol secondary loop operating at 20 degrees F. What minimum concentration by volume of propylene glycol is required to maintain freeze protection down to 5 degrees F?

• A15 percent propylene glycol concentration.
• B35 percent propylene glycol concentration.
• C55 percent propylene glycol concentration.
• D75 percent propylene glycol concentration.

During the installation of copper refrigerant piping, dry nitrogen must be continuously purged through the tubing while brazing. What regulated pressure range should be maintained during purging to prevent internal copper oxidation without blowing out molten filler metal?

• A10 to 15 psig continuous nitrogen flow.
• B15 to 25 psig continuous nitrogen flow.
• C2 to 5 psig continuous nitrogen flow.
• D30 to 50 psig continuous nitrogen flow.

When evacuating a newly installed commercial refrigeration system prior to charging, what maximum pressure reading on a deep vacuum micron gauge indicates proper dehydration and non-condensable removal before isolating the pump?

• A2,000 microns measured on vacuum gauge.
• B1,500 microns measured on vacuum gauge.
• C1,000 microns measured on vacuum gauge.
• D500 microns measured on vacuum gauge.

Per California Mechanical Code Chapter 11, where must the discharge pipe from a pressure relief valve installed on a high-pressure liquid receiver terminate?

• AOutside the building to an approved location.
• BInside the machinery room floor drain sump.
• CDirectly into the compressor suction header.
• DInto an unvented equipment electrical cabinet.

After evacuating a refrigeration system down to 500 microns, the vacuum pump is blanked off. What maximum pressure rise over a 15-minute standing vacuum decay test confirms that the system is moisture-free and leak-tight?

• APressure must remain completely static at 0.
• BPressure does not exceed 1,000 microns maximum.
• CPressure does not exceed 2,500 microns maximum.
• DPressure does not exceed 5,000 microns maximum.

When installing a thermostatic expansion valve sensing bulb on a 1-1/8 inch OD horizontal suction line, at what clock position should the bulb be securely attached?

• ADirectly on top of line at 12 o'clock.
• BDirectly at bottom of line at 6 o'clock.
• CAt the 4 o'clock or 8 o'clock position.
• DOn any uninsulated vertical pipe elbow.

According to California Mechanical Code requirements, what gas must be used to perform a high-pressure strength and leak test on a newly installed R-410A piping system?

• ACompressed oxygen gas supply cylinder.
• BCompressed air from an oil-lubricated service pump.
• CR-22 refrigerant gas without any tracer.
• DDry nitrogen gas with optional trace refrigerant.

Which brazing filler metal classification is required for joining copper-to-copper tubing without flux in commercial refrigeration piping installations?

• AAWS BCuP series phosphorus-copper alloy.
• BAWS BAg-1 high silver lead-bearing solder.
• C95/5 tin-antimony soft soldering wire alloy.
• D60/40 lead-tin electrical grade solder resin.

An installer is charging an R-410A system. High-side gauge pressure is 335 psig (saturation temp 104 degrees F per P-T chart). Liquid line temp measured at the TXV inlet is 92 degrees F. What is the liquid subcooling value?

• A8 degrees Fahrenheit liquid subcooling.
• B12 degrees Fahrenheit liquid subcooling.
• C16 degrees Fahrenheit liquid subcooling.
• D20 degrees Fahrenheit liquid subcooling.

During commissioning of a walk-in freezer with R-404A, suction pressure is 30 psig (dew point saturation temp 0 degrees F). The suction line temp measured at the evaporator outlet is 10 degrees F. What is the evaporator superheat?

• A4 degrees Fahrenheit evaporator superheat.
• B7 degrees Fahrenheit evaporator superheat.
• C10 degrees Fahrenheit evaporator superheat.
• D14 degrees Fahrenheit evaporator superheat.

How must a directional liquid line filter-drier be oriented during installation to ensure proper desiccant filtration and prevent internal screen breakdown?

• AWith the label text positioned upside down.
• BWith the outlet pointing towards compressor.
• CWith the internal bypass valve facing upward.
• DWith arrow matching liquid flow direction.

What minimum slope per foot must be provided when installing condensate drain lines from walk-in cooler evaporator pans to the indirect waste drain point?

• A1/4 inch per foot uniform downward pitch.
• B1/8 inch per foot uniform downward pitch.
• C1/2 inch per foot uniform downward pitch.
• D1 inch per foot uniform downward pitch.

Why must compressor crankcase heaters be energized for a minimum period of 12 to 24 hours prior to initial system compressor startup?

• ATo warm the motor windings to lower resistance readings.
• BTo boil off liquid refrigerant from compressor oil.
• CTo pressurize the discharge manifold assembly.
• DTo calibrate the low pressure safety switch.

When commissioning a semi-hermetic compressor, where should the oil level register in the crankcase sight glass while operating under full steady-state load?

• ACompletely filling the top glass view area.
• BBelow the bottom rim of the view sight glass.
• C1/4 to 3/4 sight glass level height range.
• DRapidly foaming across the entire viewing window.

In a refrigeration piping system where an evaporator is located 20 feet below the condensing unit, what piping trap arrangement must be installed at the base of the suction riser?

• AAn inverted loop extending above the condenser.
• BA straight vertical pipe with no fittings.
• CA double horizontal bypass with needle valve.
• DA P-trap at the bottom of vertical riser.

How should flexible metallic vibration eliminators be installed relative to a reciprocating compressor crankshaft centerline?

• AParallel to crankshaft line of motion.
• BPerpendicular with severe 90 degree offset.
• CTightly compressed to absorb end thrust.
• DTwisted 45 degrees to prevent metal fatigue.

When wiring a liquid line solenoid valve coil for automatic pump-down control, how should the solenoid coil be electrically interlocked in the control circuit?

• AIn series with the high pressure safety switch.
• BIn series with the room thermostat contacts.
• CParallel across the crankcase heater circuit.
• DDirectly to the evaporator fan motor leads.

Why must closed-cell elastomeric insulation on cold suction lines have all butt joints continuously sealed with approved vapor barrier adhesive?

• ATo increase acoustic sound dampening strength.
• BTo protect tubing from mechanical abrasion.
• CTo prevent ambient air moisture condensation.
• DTo satisfy structural building load codes.

When mounting a unit cooler inside a walk-in freezer, what minimum clearance between the rear of the evaporator coil and the room wall is required for proper air intake circulation?

• A2 inches minimum clearance distance.
• B4 inches minimum clearance distance.
• C6 inches minimum clearance distance between the coils
• DEqual to coil depth or manufacturer specification.

When installing a high-pressure liquid receiver in a commercial system, what service fitting valve must be installed on the outlet liquid line to facilitate system pump-down and servicing?

• AKing valve (king service shutoff valve).
• BSchrader core access fitting only.
• CNon-return ball check valve assembly only.
• DAtmospheric pressure relief plug.

Why must 400-series zeotropic refrigerant mixtures (such as R-404A or R-407C) always be removed from the charging cylinder as liquid rather than vapor during system charging?

• ATo accelerate the rate of refrigerant cylinder transfer.
• BTo prevent refrigerant fractionation blend changes.
• CTo prevent thermal breakdown of ester oil.
• DTo reduce pressure inside system lines.

An installer sets a low-pressure control on an R-134a medium-temp cooler. Desired cut-in pressure is 35 psig (40 degrees F saturation) and desired cut-out is 18 psig (20 degrees F saturation). What is the required differential setting?

• A10 psig required pressure differential.
• B14 psig required pressure differential.
• C17 psig required pressure differential.
• D22 psig required pressure differential.

Per California Mechanical Code Chapter 11, plastic piping materials used in secondary cooling loops inside commercial building plenums must comply with what maximum flame spread and smoke development index rating?

• A75 flame spread and 100 smoke developed rating.
• B50 flame spread and 200 smoke developed.
• C35 flame spread and 150 smoke developed.
• D25 flame spread and 50 smoke developed rating.

Where should a pressure-actuated water regulating valve be installed on a water-cooled condenser, and how is its sensing capillary line connected?

• AOn condenser water outlet; capillary to discharge.
• BOn condenser water inlet; capillary to suction.
• COn cooling tower pump; capillary to oil pump.
• DOn city main supply line; capillary to evaporator.

In a multi-evaporator system connected to a single compressor rack where evaporators operate at different temperatures, what control valve must be installed in the suction line of the warmer evaporator?

• ACrankcase pressure regulator (CPR) valve.
• BEvaporator pressure regulator (EPR) valve.
• CThermostatic expansion valve with equalizer.
• DHigh-side float expansion valve fitting.

When installing low-ambient head pressure controls (ORI/ORD system), what is the specific operational function of the ORD (open on pressure differential) valve?

• AThrottles suction gas to compressor motor.
• BBypasses liquid from receiver to condenser.
• CBypasses hot gas from discharge to receiver.
• DVents excess pressure to external atmosphere.

What internal component inside a suction line accumulator ensures oil returns to the compressor while preventing liquid refrigerant slugging?

• AA weighted high-pressure relief flapper.
• BA manual brass needle metering valve.
• CA thermal bimetallic expansion disc plate only.
• DA metering orifice with screen at U-tube base.

A commercial walk-in cooler exhibits high evaporator superheat (35 degrees F), low suction pressure (12 psig on R-134a), normal liquid subcooling (10 degrees F), and low compressor amp draw. What is the most probable system fault?

• ARestricted TXV inlet screen or valve orifice.
• BOvercharged refrigerant system level.
• CFailed condenser fan motor running slow.
• DLeaking compressor discharge reed valve assembly.

A low-temperature system exhibits 0 degrees F superheat, compressor body frost, high suction pressure, and heavy internal knocking noises. What immediate repair adjustment is required?

• AAdd refrigerant charge to increase pressure.
• BAdjust TXV clockwise to increase superheat.
• CReplace condenser fan blade assembly.
• DClean dirty condenser air filter fins.