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MT Journeyman Plumber practice questions

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Question 1Uniform Plumbing Code (2021 UPC) application and installation standards

Under the 2021 UPC, what is the minimum size of a building sewer serving a single dwelling unit where only gravity flow is used?

  1. 6 inches
  2. 3 inches Correct answer.
  3. 4 inches
  4. 2 inches

Explanation

The UPC sets the minimum building sewer size at 3 inches for a single dwelling unit and requires that the sewer be no smaller than the building drain it serves. A 2-inch line is permitted only for certain special cases such as pumped discharge, not ordinary gravity drainage.

Question 2Uniform Plumbing Code (2021 UPC) application and installation standards

A horizontal drainage pipe is installed at a slope of 1/8 inch per foot. What minimum pipe size does the UPC require for this slope to be acceptable?

  1. 2 inches
  2. 4 inches Correct answer.
  3. 6 inches
  4. 3 inches

Explanation

The UPC permits 1/8 inch per foot fall only on drainage pipe 4 inches and larger; smaller pipe must slope at 1/4 inch per foot. This ensures adequate scouring velocity in larger lines where the flatter grade is allowed.

Question 3Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum trap seal depth required for a plumbing fixture trap under the UPC?

  1. 2 inches Correct answer.
  2. 1 inch
  3. 3 inches
  4. 4 inches

Explanation

The UPC requires each fixture trap to maintain a liquid seal of at least 2 inches and no more than 4 inches of depth. The 2-inch minimum resists sewer gas while the 4-inch maximum limits the seal's tendency to siphon.

Question 4Uniform Plumbing Code (2021 UPC) application and installation standards

A fixture drain connects to a vertical stack. Within what maximum vertical distance above the stack fitting must the trap arm's vent connection be taken?

  1. The vent must connect within the trap arm length that does not exceed the fixture's trap-to-vent distance Correct answer.
  2. The vent must be within 12 inches of the trap weir
  3. The trap arm may run any distance if sloped properly
  4. The vent must be within 5 feet of the stack regardless of pipe size

Explanation

The UPC limits the developed length of a trap arm by the distance allowed between the trap weir and the vent, which varies with pipe size. Exceeding that distance risks self-siphoning of the trap seal.

Question 5Uniform Plumbing Code (2021 UPC) application and installation standards

When is a plumbing vent permitted to terminate below a window or within a specific distance of an operable opening?

  1. Vents may terminate anywhere on a sidewall if a screen is installed
  2. Vents may terminate 3 feet below a window if the window is fixed
  3. Vents may terminate on a sidewall only if they are at least 10 feet above or 10 feet horizontally from openings Correct answer.
  4. Never; vents must always extend above the roof line

Explanation

The UPC allows sidewall vent termination only when the outlet is located at least 10 feet above or 10 feet horizontally from any window, door, or other air intake opening. This prevents sewer gas from re-entering the building.

Question 6Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum air gap required for a fixture with an effective opening of 1 inch or less when the fixture is not affected by a back-pressure condition?

  1. One inch minimum regardless of outlet size
  2. One-half the effective opening of the outlet
  3. Twice the diameter of the outlet
  4. Equal to the diameter of the outlet Correct answer.

Explanation

For a non-back-pressure air gap, the UPC requires the gap to be at least equal to the diameter of the supply outlet, with a minimum of 1 inch. This physical separation prevents backsiphonage contamination.

Question 7Uniform Plumbing Code (2021 UPC) application and installation standards

A water heater is installed in a garage. What protection does the UPC require for the ignition source?

  1. The heater must be enclosed in a fire-rated cabinet
  2. The heater must be elevated so the ignition source is at least 18 inches above the floor Correct answer.
  3. The heater must be installed on a 4-inch concrete pad
  4. No special protection is required if the heater is electric

Explanation

The UPC requires water heaters in garages to be elevated so that the ignition source is at least 18 inches above the floor to reduce the risk of igniting gasoline vapors. This applies to fuel-fired appliances with pilot lights or other ignition sources.

Question 8Uniform Plumbing Code (2021 UPC) application and installation standards

What minimum clearance must be maintained between an unlisted water heater and combustible construction under the UPC's general rule?

  1. 24 inches
  2. 6 inches
  3. 0 inches
  4. 12 inches Correct answer.

Explanation

Under the UPC's general rule, an unlisted water heater requires 12 inches of clearance from combustible construction. Listed water heaters follow the clearances in their approved listing and manufacturer's instructions, subject to applicable adopted amendments.

Question 9Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum size of a water service pipe serving a single-family dwelling under the UPC?

  1. 1 inch
  2. 1/2 inch
  3. 3/4 inch Correct answer.
  4. 5/8 inch

Explanation

The UPC sets the minimum water service pipe size for a single-family dwelling at 3/4 inch. Smaller sizes are not permitted for the service even if the fixture load is light.

Question 10Uniform Plumbing Code (2021 UPC) application and installation standards

A horizontal branch drain receives a discharge from a kitchen sink. What is the minimum size of the trap arm for that sink?

  1. 1-1/4 inches
  2. 2 inches
  3. 1-1/2 inches Correct answer.
  4. 3 inches

Explanation

The UPC requires a minimum 1-1/2 inch trap and trap arm for a kitchen sink, reflecting the fixture's drainage load. Smaller sizes cannot adequately carry the waste.

Question 11Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum size of a vent stack serving a drainage stack in a building?

  1. 2 inches
  2. 1-1/4 inches Correct answer.
  3. 3 inches
  4. 1-1/2 inches

Explanation

The UPC allows vent stacks to be as small as 1-1/4 inch, provided the vent capacity is adequate for the drainage stack it serves. The size is based on the fixture units and stack length.

Question 12Uniform Plumbing Code (2021 UPC) application and installation standards

A clothes washer standpipe is installed. What is the minimum height of the standpipe above the trap weir?

  1. 30 inches
  2. 18 inches
  3. 24 inches Correct answer.
  4. 12 inches

Explanation

The UPC requires a clothes washer standpipe to be at least 24 inches in length above the trap weir to accommodate the discharge rate of the washer pump. This prevents overflow during discharge.

Question 13Uniform Plumbing Code (2021 UPC) application and installation standards

What is the maximum developed length of a trap arm for a 1-1/2 inch fixture drain?

  1. 6 feet
  2. 8 feet
  3. 3 feet 6 inches Correct answer.
  4. 5 feet

Explanation

The UPC limits the trap arm for a 1-1/2 inch drain to a developed length of 3 feet 6 inches at the standard 1/4 inch per foot slope. Longer trap arms risk self-siphoning of the trap seal.

Question 14Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum number of fixture units that a 3-inch horizontal drainage branch may carry?

  1. 20
  2. 30
  3. 42 Correct answer.
  4. 60

Explanation

The UPC drainage tables assign a maximum of 42 fixture units to a 3-inch horizontal branch at the standard slope. This capacity reflects the hydraulic load the pipe can handle while maintaining scouring velocity.

Question 15Uniform Plumbing Code (2021 UPC) application and installation standards

A floor drain is installed in a food preparation area. What backflow protection is required for the indirect waste connection?

  1. A vacuum breaker on the supply line
  2. An air gap equal to twice the pipe diameter
  3. An air break with the drain terminating above the flood-level rim Correct answer.
  4. A check valve on the drain line

Explanation

Indirect waste from food preparation fixtures must discharge through an air break or air gap, with the pipe terminating above the flood-level rim of the receptor. This prevents sewage from backing into the fixture.

Question 16Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum size of a building drain serving a building with more than one dwelling unit?

  1. 6 inches
  2. 3 inches Correct answer.
  3. 4 inches
  4. 2 inches

Explanation

The UPC requires the building drain to be at least 3 inches for a building with multiple dwelling units, matching the minimum building sewer size. Smaller drains cannot carry the combined load.

Question 17Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum distance a water closet must be set from a side wall to allow proper clearance?

  1. 18 inches
  2. 12 inches
  3. 24 inches
  4. 15 inches Correct answer.

Explanation

The UPC requires at least 15 inches of clearance from the centerline of a water closet to any side wall or partition. This provides usable space for the occupant and access for maintenance.

Question 18Uniform Plumbing Code (2021 UPC) application and installation standards

A grease interceptor is required for a commercial kitchen. What is the minimum capacity required by the UPC for a grease interceptor?

  1. 20 gallons
  2. 100 gallons
  3. 50 gallons
  4. 10 gallons Correct answer.

Explanation

The UPC sets a minimum grease interceptor capacity of 10 gallons, though the actual size is calculated from the fixture load and discharge rate. The minimum ensures a baseline retention volume.

Question 19Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum size of a vent pipe serving a single fixture where the vent is not a stack?

  1. 1-1/2 inches
  2. 3 inches
  3. 1-1/4 inches Correct answer.
  4. 2 inches

Explanation

The UPC permits individual fixture vents to be as small as 1-1/4 inch, provided the vent capacity is adequate. Larger sizes are used when multiple fixtures are combined.

Question 20Uniform Plumbing Code (2021 UPC) application and installation standards

A sump pump discharges into the building drainage system. What backflow protection is required?

  1. A check valve on the discharge line
  2. A vacuum breaker on the pump
  3. An air break with the discharge terminating above the flood-level rim of the receptor Correct answer.
  4. An air gap

Explanation

Pumped discharge into a drainage receptor must terminate through an air break above the flood-level rim to prevent sewage backflow into the pump and sump. This physical separation is the required protection.

Question 21Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum slope for a 2-inch horizontal drainage pipe under the UPC?

  1. 1/2 inch per foot
  2. 1/4 inch per foot Correct answer.
  3. 1/8 inch per foot
  4. 1 inch per foot

Explanation

The UPC requires 1/4 inch per foot slope for drainage pipe smaller than 4 inches. The flatter 1/8 inch per foot slope is reserved for 4-inch and larger pipe.

Question 22Uniform Plumbing Code (2021 UPC) application and installation standards

A water closet is installed in a public restroom. What is the minimum clearance required in front of the fixture?

  1. 24 inches Correct answer.
  2. 30 inches
  3. 21 inches
  4. 15 inches

Explanation

The UPC requires at least 24 inches of clearance in front of a water closet to the nearest obstruction. This allows the occupant to use the fixture and provides access for cleaning and repair.

Question 23Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum size of a water closet drain under the UPC?

  1. 2 inches
  2. 4 inches
  3. 3 inches Correct answer.
  4. 6 inches

Explanation

The UPC requires a minimum 3-inch drain for a water closet to carry the high discharge volume of the fixture. Smaller drains cannot adequately handle the flush.

Question 24Uniform Plumbing Code (2021 UPC) application and installation standards

A backflow preventer is installed on a lawn irrigation system. What type of device does the UPC require for a system with a potential for backpressure?

  1. A double check valve assembly
  2. An atmospheric vacuum breaker
  3. A hose bibb vacuum breaker
  4. A reduced pressure principle backflow prevention assembly Correct answer.

Explanation

Where backpressure or a high hazard exists, the UPC requires a reduced pressure principle backflow prevention assembly, which provides both a check and a relief valve for reliable protection.

Question 25Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum distance a vent terminal must be from a property line?

  1. 3 feet Correct answer.
  2. 10 feet
  3. 15 feet
  4. 5 feet

Explanation

The UPC requires a vent terminal to be at least 3 feet from a property line to prevent sewer gas from crossing onto adjacent property. This separation applies to the vent outlet location.

Question 26Uniform Plumbing Code (2021 UPC) application and installation standards

Under the 2021 UPC, what is the minimum diameter of a building sewer?

  1. 4 inches
  2. 2 inches
  3. 3 inches Correct answer.
  4. 6 inches

Explanation

The 2021 UPC requires a building sewer to be not less than 3 inches in diameter. This minimum applies to the sewer carrying the building drainage to the public sewer or private disposal system.

Question 27Uniform Plumbing Code (2021 UPC) application and installation standards

What is the maximum allowable horizontal distance between the trap weir and the vent connection (trap arm length) for a 2-inch fixture drain, based on a 1/4 inch per foot slope?

  1. 6 feet
  2. 10 feet
  3. 5 feet
  4. 8 feet Correct answer.

Explanation

The UPC limits the developed length of a trap arm based on pipe size and slope so the trap weir stays within the vent's protection. For a 2-inch trap arm at 1/4 inch per foot, the maximum developed length is 8 feet.

Question 28Uniform Plumbing Code (2021 UPC) application and installation standards

A lavatory drain connects to a horizontal branch. What minimum size of vent is required for a single lavatory where the vent is not a stack?

  1. 3 inches
  2. 2 inches
  3. 1-1/2 inches
  4. 1-1/4 inches Correct answer.

Explanation

The UPC permits a minimum vent size of 1-1/4 inch for a single fixture such as a lavatory where the vent does not serve as a stack. Larger vents are permitted but not required.

Question 29Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum required size of a water heater relief valve discharge pipe?

  1. Equal to the valve outlet size Correct answer.
  2. One nominal size larger than the outlet
  3. One nominal size smaller than the outlet
  4. One-half inch inside diameter

Explanation

The relief valve discharge pipe must be the full size of the valve outlet and must not be reduced. It must discharge by gravity to a safe location.

Question 30Uniform Plumbing Code (2021 UPC) application and installation standards

A fixture has a 2-inch effective opening. What is the minimum required air gap for a backflow prevention installation?

  1. One inch
  2. Two inches
  3. Four inches
  4. Three inches Correct answer.

Explanation

For fixtures with an effective opening greater than 1 inch, the UPC requires an air gap of at least twice the effective opening size. Twice a 2-inch opening gives a minimum air gap of 3 inches, with a minimum of 1 inch in any case.

Question 31Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum slope required for a 4-inch horizontal drainage pipe under the UPC?

  1. 1/2 inch per foot
  2. 1/4 inch per foot
  3. 1/8 inch per foot Correct answer.
  4. 1/16 inch per foot

Explanation

The UPC requires horizontal drainage piping 4 inches and larger to be sloped at not less than 1/8 inch per foot. Smaller pipe sizes require 1/4 inch per foot.

Question 32Uniform Plumbing Code (2021 UPC) application and installation standards

How far must a cleanout be extended above a finished floor when it is installed in a floor?

  1. Not less than 1/4 inch above the floor
  2. Not less than 6 inches above the floor
  3. Not less than 12 inches above the floor
  4. Flush with the floor Correct answer.

Explanation

A cleanout installed in a floor may be set flush with the finished floor and provided with a countersunk or recessed plug. This keeps it accessible while not creating a trip hazard.

Question 33Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum size of a vent terminal pipe where the vent extends through a roof?

  1. 2 inches
  2. 1-1/4 inches Correct answer.
  3. 1-1/2 inches
  4. 3 inches

Explanation

The UPC requires a roof vent terminal to be not less than 1-1/4 inches in diameter. This minimum ensures adequate venting capacity at the terminal.

Question 34Uniform Plumbing Code (2021 UPC) application and installation standards

A building has a 3-inch drainage stack. What is the minimum size of the vent stack serving it?

  1. 3 inches
  2. 1-1/2 inches
  3. 4 inches
  4. 2 inches Correct answer.

Explanation

The UPC requires a vent stack to be at least one-half the diameter of the drainage stack it serves, but not less than 1-1/4 inch. Half of a 3-inch stack is 1-1/2 inch, so 2 inches satisfies the requirement as the smallest listed option above that threshold.

Question 35Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum required diameter of a building drain serving a building with one water closet and one lavatory?

  1. 3 inches Correct answer.
  2. 2 inches
  3. 1-1/2 inches
  4. 4 inches

Explanation

The UPC requires a building drain to be not less than 3 inches in diameter regardless of the small fixture load. The building drain carries the combined discharge to the building sewer.

Question 36Uniform Plumbing Code (2021 UPC) application and installation standards

A water closet is installed with its centerline measured from a side wall. What is the minimum centerline distance required?

  1. 18 inches
  2. 15 inches Correct answer.
  3. 12 inches
  4. 24 inches

Explanation

The UPC requires a water closet centerline to be at least 15 inches from any side wall or partition. This provides adequate clearance for use and cleaning.

Question 37Uniform Plumbing Code (2021 UPC) application and installation standards

What is the minimum clearance required in front of a water closet measured from the bowl to the opposite wall or fixture?

  1. 15 inches
  2. 24 inches Correct answer.
  3. 21 inches
  4. 18 inches

Explanation

The UPC requires not less than 24 inches of clear space in front of a water closet, measured from the front of the bowl to any wall or fixture. This ensures usable access.

Question 38Uniform Plumbing Code (2021 UPC) application and installation standards

What minimum size of water service pipe is required for a single-family dwelling under the UPC?

  1. 3/4 inch Correct answer.
  2. 1 inch
  3. 1-1/2 inches
  4. 1/2 inch

Explanation

The UPC requires the water service pipe for a single-family dwelling to be not less than 3/4 inch in diameter. This minimum supports the fixture demand of the dwelling.

Question 39Uniform Plumbing Code (2021 UPC) application and installation standards

A commercial kitchen sink is installed. What is the minimum size of the fixture drain and trap for a sink with three compartments?

  1. 2 inches
  2. 2-1/2 inches
  3. 1-1/2 inches Correct answer.
  4. 3 inches

Explanation

The UPC requires a minimum fixture drain and trap size of 1-1/2 inches for a commercial sink. Larger sizes are permitted but the code minimum is 1-1/2 inches.

Question 40Uniform Plumbing Code (2021 UPC) application and installation standards

A floor drain in a food preparation area receives an indirect waste connection. What backflow protection is required at the connection?

  1. An air gap of at least twice the effective opening Correct answer.
  2. A check valve in the drain line
  3. A vacuum breaker on the drain line
  4. A backwater valve on the branch

Explanation

Indirect waste from a food preparation fixture must discharge through an air gap or air break that prevents backflow into the fixture. An air gap of at least twice the effective opening is required.

Question 41Uniform Plumbing Code (2021 UPC) application and installation standards

A backflow preventer is installed on a lawn irrigation system with a chemical injection. What type of device does the UPC require?

  1. A hose bibb vacuum breaker
  2. A double check valve assembly
  3. A reduced pressure principle backflow preventer Correct answer.
  4. An atmospheric vacuum breaker

Explanation

When a lawn irrigation system includes chemical injection, the UPC requires a reduced pressure principle backflow preventer to protect the potable supply. This device provides the highest level of protection against backflow.

Question 42Uniform Plumbing Code (2021 UPC) application and installation standards

A horizontal drainage pipe is installed with a uniform fall. Which statement describes how the required slope is determined under the 2021 UPC for a 2-inch pipe?

  1. A slope of 1/2 inch per foot is required for 2-inch pipe.
  2. A slope of 1/16 inch per foot is permitted for 2-inch pipe.
  3. A slope of 1/8 inch per foot is permitted for 2-inch pipe.
  4. A slope of 1/4 inch per foot is required for 2-inch pipe. Correct answer.

Explanation

The UPC slope table requires 2-inch horizontal drainage pipe to be installed at a fall of 1/4 inch per foot. Smaller pipes such as 1-1/4 inch use 1/4 inch per foot as well, while larger pipes may be permitted at 1/8 inch per foot. The slope must be uniform and in the direction of flow.

Question 43Uniform Plumbing Code (2021 UPC) application and installation standards

A horizontal branch drain receives the discharge of a clothes washer standpipe. What does the UPC require regarding the trap serving this standpipe?

  1. The standpipe trap may be omitted if the standpipe is 30 inches long.
  2. The standpipe trap must be a drum trap.
  3. The standpipe trap must be installed below the floor slab.
  4. The standpipe trap must be self-cleaning and accessible. Correct answer.

Explanation

Fixture traps must be of a design that is self-cleaning and must be accessible for service. A standpipe serving a clothes washer requires a trap of the proper type at its base, and the trap must remain accessible. Drum traps are prohibited in most applications because they cannot be cleaned properly.

Question 44Uniform Plumbing Code (2021 UPC) application and installation standards

A water distribution system in a building is being pressure tested before occupancy. Which test method satisfies the 2021 UPC for the water piping?

  1. A hydrostatic test at the working pressure of the system held for 30 minutes.
  2. A visual inspection of all joints with no pressure applied.
  3. A hydrostatic test at not less than the working pressure held for at least 60 minutes. Correct answer.
  4. A 50 psi air test held for 15 minutes with no drop in pressure.

Explanation

The UPC requires water distribution piping to be tested hydrostatically at not less than the working pressure of the system, and the test must be maintained for at least 60 minutes. This allows leaks at joints and fittings to become evident. Air testing is not the prescribed method for this piping test.

Question 45Uniform Plumbing Code (2021 UPC) application and installation standards

A plumbing fixture is installed in a room, and the fixture is not adjacent to a wall. What does the UPC require for the fixture's access and clearance?

  1. The fixture must be centered in the room regardless of other fixtures.
  2. The fixture must be installed with at least 15 inches of clearance from any side obstruction.
  3. The fixture must be enclosed by a partition on all sides.
  4. The fixture must be accessible for cleaning and service, with clear space maintained in front. Correct answer.

Explanation

The UPC requires plumbing fixtures to be accessible for cleaning and service, and the clear space in front of the fixture must be maintained so it can be used. Fixtures must also be installed so that they can be reached for repair. Centering a fixture or enclosing it is not a general requirement.

Question 46Uniform Plumbing Code (2021 UPC) application and installation standards

A building sewer discharges to a public sewer, and a cleanout is installed at the building sewer. What does the UPC require for the cleanout at the building sewer?

  1. The cleanout must be installed only inside the building.
  2. The cleanout may be omitted if the building sewer is shorter than 10 feet.
  3. The cleanout must be one pipe size smaller than the building sewer.
  4. The cleanout must be the same size as the building sewer and installed at the junction. Correct answer.

Explanation

A cleanout is required at the junction where the building sewer meets the building drain, and it must be the same size as the building sewer. This provides access for clearing blockages in the sewer. The cleanout must also be accessible and properly capped.

Question 47Uniform Plumbing Code (2021 UPC) application and installation standards

An indirect waste receptor receives the discharge of a commercial dishwasher. What does the UPC require for the air gap or air break at this connection?

  1. The indirect waste pipe must be connected directly to the drainage system.
  2. The indirect waste pipe must be vented through the roof.
  3. The indirect waste pipe must discharge into a receptor with an air break, and the receptor must be trapped. Correct answer.
  4. The indirect waste pipe must discharge through an air gap of at least twice the diameter of the pipe.

Explanation

An indirect waste connection must discharge into a receptor with an air break or air gap, and the receptor itself must be trapped and vented. This prevents sewage backflow from contaminating the fixture or the food-preparation area. A direct connection would defeat the purpose of the indirect waste.

Question 48Uniform Plumbing Code (2021 UPC) application and installation standards

A vent stack is installed to serve a drainage stack. Under the 2021 UPC, which statement best describes the required vent stack sizing relative to the drainage stack?

  1. The vent stack must be sized according to the drainage load it serves, using the vent sizing tables. Correct answer.
  2. The vent stack must be the same size as the drainage stack regardless of load.
  3. The vent stack must be larger than the drainage stack in all cases.
  4. The vent stack must be at least one-half the diameter of the drainage stack.

Explanation

Vent stacks are sized according to the drainage fixture units they serve, using the vent sizing tables in the UPC. The size is not determined by a fixed ratio to the drainage stack diameter. The length and developed length of the vent also affect the permitted size.

Question 49Uniform Plumbing Code (2021 UPC) application and installation standards

A water heater is installed in a building, and the temperature and pressure relief valve is being piped. Which installation detail is required by the UPC for the relief valve discharge?

  1. The discharge pipe must be connected directly to the drainage system without an air gap.
  2. The discharge pipe must be trapped before terminating.
  3. The discharge pipe must be reduced to a smaller size at the outlet.
  4. The discharge pipe must terminate not more than 6 inches above the floor or receptor. Correct answer.

Explanation

The relief valve discharge pipe must terminate within 6 inches of the floor or a receptor, and it must not be trapped or reduced in size. The discharge must be directed to a safe place of disposal. This arrangement prevents scalding and allows the valve to relieve pressure safely.

Question 50Uniform Plumbing Code (2021 UPC) application and installation standards

A grease interceptor is installed to serve a commercial kitchen. Under the UPC, which statement describes the required venting of the interceptor?

  1. The interceptor must be vented through the building sewer.
  2. The interceptor must be vented through a vent pipe sized and installed in accordance with the venting provisions. Correct answer.
  3. The interceptor does not require venting if it is installed outside the building.
  4. The interceptor must be vented only through the fixture drain.

Explanation

A grease interceptor must be vented so that gases can escape and the interceptor can function properly. The vent must be sized and installed according to the venting provisions of the UPC. Venting through the fixture drain or the building sewer does not satisfy this requirement.