MPLE Board Exam cheat sheet

The National Plumbing Code of the Philippines (NPCP) is the reference code for the MPLE; R.A. 1378 (Plumbing Law) gives the code its legal force and created the Board of Master Plumbers.

Fixture unit (FU) values: water closet (tank type) = 3 FU; lavatory = 1 FU; bathtub = 2 FU; shower head = 2 FU; kitchen sink = 2 FU; floor drain = 2 FU; urinal (flush valve) = 5 FU.

Minimum trap arm length rule: the developed length of a trap arm must be at least 2 times the trap arm diameter, and the fall must not exceed one pipe diameter to prevent siphonage.

Vent stack sizing depends on the total fixture units served and the stack length; a 1-1/2 in vent serves up to 8 FU at 1 in stack length, but larger FU loads require 2 in or more.

Soil pipe carries sewage (water closets, urinals); waste pipe carries non-fecal liquid waste (sinks, lavatories); a combined drain carries both and must be sized for the total FU.

Cleanout requirements: a cleanout is required at the base of each soil/waste stack, at the upper end of each horizontal drain, and at intervals not exceeding 15 m (50 ft) in horizontal runs.

Water supply sizing uses the fixture unit method with the Hunter curve: convert FU to probable demand in gpm, then select pipe diameter from velocity limits (typically 1.2-2.4 m/s or 4-8 fps).

Backflow protection: an air gap (minimum 2 times the effective opening, not less than 1 in) is the only acceptable protection for high-hazard connections; a reduced-pressure-zone (RPZ) assembly protects against both backpressure and backsiphonage.

Minimum fixture drain/trap size: lavatory 1-1/4 in (1-1/2 in in some codes), kitchen sink 1-1/2 in, water closet 3 in, floor drain 2 in; the trap must be the same size as the fixture drain.

Slope requirements: 3 in and smaller horizontal drainage pipe slope at 1/4 in per foot; 4 in and larger slope at 1/8 in per foot; no drainage pipe may slope less than 1/8 in per foot.

Water service and building supply: minimum size 3/4 in for a single-family dwelling; pressure at fixtures must be at least 8 psi (residual) and not exceed 80 psi unless a pressure-reducing valve is installed.

Vent termination: vent must extend at least 6 in above the roof, be at least 3 ft from any window or air intake, and be at least 10 ft from a property line or adjoining building.

A water closet must be installed on a drain of at least 3 in diameter; the closet bend is 3 in and the stack must be at least 3 in to carry the 3 FU closet.

Interceptors: grease interceptors are required for commercial kitchens and must be sized by the fixture flow and grease retention capacity; oil/sand interceptors are required for garages and service stations.

Water heater relief valve: a temperature-pressure (T&P) relief valve is required, piped full-size to a safe discharge point, terminating not more than 6 in above the floor or outside.

Backwater valve: required on any fixture drain or building drain subject to backflow from a public sewer; the valve must be installed on the building drain downstream of the fixtures it serves.

PVC (polyvinyl chloride) is used for cold water and DWV; CPVC for hot and cold water up to 180°F (82°C); PEX for hot/cold water; GI (galvanized iron) for cold water and some drainage.

Copper tube types: Type K (thickest, underground), Type L (standard water service), Type M (thinnest, above-ground only); all are joined by soldering, brazing, or press fittings.

Cast iron soil pipe is joined by lead-and-oakum, rubber compression gaskets (no-hub), or mechanical couplings; no-hub couplings require a torque of about 60 in-lb on the clamps.

Fixture materials: vitreous china for water closets and lavatories; enameled cast iron for sinks and tubs; stainless steel for commercial sinks; acrylic/fiberglass for tubs and showers.

Fittings: a sanitary tee has a curved branch for vertical-to-horizontal flow; a wye (Y) and 1/8 bend is used for horizontal-to-horizontal drainage; a P-trap has a 2-4 in water seal.

Water closet flush valves (flushometers) require a minimum 1 in supply and 15-25 psi flowing pressure; tank-type closets require only 1/2 in supply and 8 psi.

Pipe sizing abbreviations: nominal pipe size (NPS) vs. actual OD; Schedule 40 PVC has a higher pressure rating than Schedule 20 but lower than Schedule 80 for the same nominal size.

Water hammer arrestors are installed near quick-closing valves (flushometers, solenoid valves) to absorb pressure surges; they are not a substitute for proper pipe support.

R.A. 1378 (Plumbing Law) regulates the practice of plumbing in the Philippines; it created the Board of Master Plumbers under PRC and requires registration for master plumbers.

Only a registered master plumber may prepare, sign, and seal plumbing plans and specifications; a master plumber's seal and PRC license number are required on drawings submitted for permit.

The plumbing code is enforced by the local building official and the local health officer; a plumbing permit must be secured before installation and a certificate of final inspection after.

Ethics: a master plumber must not sign plans prepared by unlicensed persons, must not accept commissions from suppliers that compromise design integrity, and must maintain client confidentiality.

Continuing professional development (CPD) units are required for license renewal under R.A. 10912; the PRC sets the number of CPD units per renewal cycle.

Conflict of interest: a master plumber serving as a consultant must disclose any financial interest in a supplier or contractor; failure to disclose is a violation of the code of ethics.

Violations: practicing without a license, falsifying plans, or allowing another to use one's seal are grounds for suspension or revocation of the license by the PRC Board.

Contract documents: the agreement between owner and plumber should specify scope, drawings, specifications, payment terms, and warranty; verbal changes should be confirmed in writing.