Punjab PSEB Sr. Sec. NSQF Plumbing (Advanced Plumbing Technician) cheat sheet

PPE selection rule: impact goggles for cutting and grinding, nitrile gloves for solvent cement, leather gloves for hot work, hard hat where overhead work is present, and safety footwear on site.

Portable electric tools on site are supplied through a 30 mA RCD/ELCB; damaged leads, missing earth pins and taped joints are removed from service.

Oxy-acetylene storage: cylinders upright and capped, oxygen and fuel gas at least 6 m apart or separated by a 1.5 m fire-resistant partition, with flashback arrestors on both regulators.

Confined-space entry requires a permit, isolation, ventilation and gas testing: oxygen 19.5–23.5%, flammable gas below 10% LEL, hydrogen sulphide below 10 ppm, with a standby attendant outside.

Before excavation, locate buried water, gas and electric services; keep spoil and materials at least 0.6 m from the trench edge and provide a ladder for access.

Thermal burn first aid: cool the burn under running water for 20 minutes, remove rings or tight items, cover with a sterile non-stick dressing, and do not apply ice or grease.

Solvent cement, primer and PVC dust are flammable or irritant; use forced ventilation, keep ignition sources away, and provide eyewash where cement is mixed or applied.

Lockout/tagout rule: isolate the electrical or water supply, release stored pressure, tag the isolation point, and verify zero energy before repair or maintenance.

Work at height: use a harness anchored above shoulder level, guardrail openings, and keep aluminium ladders away from live electrical lines.

Galvanised steel water pipe to IS 1239 is supplied in light, medium and heavy classes; medium class is common for domestic water lines, and threads are BSPT.

PVC-U pipe to IS 4985 is for cold potable water; CPVC is for hot water; do not join CPVC with PVC solvent cement because the cements are formulated for different polymers.

Valve decision rule: gate valve for isolation, globe valve for throttling, ball valve for quick quarter-turn shutoff, butterfly valve for large diameters, check valve for one-way flow, PRV for pressure reduction.

A pipe wrench grips on the pipe or fitting; choose a wrench size matched to the pipe, pull the handle toward the pipe, and never extend the handle with a cheater bar.

Hacksaw blade selection: 18 teeth per inch for thick-wall steel pipe and 24 teeth per inch for thin-wall pipe and copper; cut square and ream internal burrs.

Copper water tube types K, L and M have decreasing wall thickness; type K is heaviest for underground and high-pressure work, type M is lightest for above-ground low-pressure work.

Common fittings: 90° or 45° elbow changes direction, tee branches, reducer changes diameter, coupling joins same-size pipes, union allows dismantling, nipple is a short threaded piece, cap closes an end.

Thermoplastic pressure ratings fall as temperature rises; CPVC is rated to about 93°C, and pipes must be derated for hot-water service according to the manufacturer's temperature-pressure table.

Measure pipe centre-to-centre and face-to-face, subtract fitting take-outs, and add allowance for threads or solder sockets before cutting.

BSPT threads have a 1:16 taper on diameter; cut with sharp dies and cutting oil, blow out chips, and apply PTFE tape clockwise or pipe dope to the male thread.

Thread engagement rule: hand-tight plus about 3 to 4 turns with a wrench; over-tightening splits fittings and under-tightening leaves leaking threads.

Soldering sequence: clean to bright metal, apply flux, heat the fitting until solder melts on contact, feed lead-free solder into the joint gap, and let capillary action fill it.

Brazing uses filler that melts above 450°C; copper-phosphorus filler joins copper to copper without flux, while silver-based filler with flux joins copper to brass or steel.

Purge nitrogen through copper pipe during brazing to prevent internal oxidation scale, which can block valves and strainers.

Solvent cementing PVC: apply primer to both surfaces, apply cement to both, assemble with a quarter turn, hold 15–30 seconds, and allow full cure before pressure testing.

Fusion temperatures: PP-R socket fusion uses a hot plate at about 260°C; PE butt fusion uses a heater plate at about 200–230°C; clean and mark insertion depth first.

Install a dielectric union between copper and galvanised steel to break galvanic coupling; direct contact causes the steel to corrode at the joint.

Do not use lead-based solder on potable water lines; lead-free solder and lead-free flux are required for drinking-water joints.

Domestic water demand is commonly taken as 135 litres per capita per day; peak demand may be 2–3 times the average hourly flow.

Pressure conversion: 1 bar equals about 10.2 m of water head; 1 psi equals about 2.31 ft of water head.

Size service pipes for 1.0–1.5 m/s velocity; keep velocities below about 3 m/s to limit noise, erosion and water hammer.

Fixture unit method: convert each fixture to water supply fixture units, sum them, apply the Hunter curve for probable simultaneous demand, then size the meter and main.

Overhead storage tank capacity is commonly at least one day's demand; the tank must be above the highest fixture and fitted with overflow, washout and insect-proof vent.

Backflow protection decision: air gap is the highest protection, reduced-pressure zone assembly for high hazard, double check valve for low hazard, and vacuum breaker for hose outlets.

Fit a pressure reducing valve where mains pressure exceeds about 3–4 bar; set downstream pressure to suit fixtures, typically 2–3 bar.

Hot-water systems need expansion control, insulation and recirculation or traced dead legs to deliver hot water quickly and limit Legionella growth.

Install water hammer arrestors near quick-closing valves and clamp pipes securely; loose pipe and high velocity increase surge damage.

Gravity drainage slope: 100 mm soil pipe is commonly laid at 1 in 50 to 1 in 100; smaller waste pipes need steeper falls to maintain self-cleansing velocity.

Each trap must retain a water seal of 50–75 mm; a seal below 50 mm is easily lost by evaporation or siphonage.

Vent stack function: admit air to the drainage system, protect trap seals from siphonage, and discharge sewer gas above the roof away from windows and air intakes.

Two-pipe system carries soil and waste in separate stacks; one-pipe system uses one stack with traps and a vent, and a single-stack system needs careful venting.

Connect horizontal drainage branches with 45° junctions or sweep fittings; a plain 90° tee on its side causes blockage and is not acceptable.

Inspection chambers are provided at changes of direction, junctions, and long straight runs so drains can be rodded and inspected.

A grease trap is required for kitchen waste before it enters the drainage line; a silt trap is used for car parks and surface water.

Drainage test methods: water test with about 1.5 m head for 30 minutes, air test, and smoke test to locate leaks and bad connections.

An air admittance valve admits air but does not allow sewer gas out; it must be accessible and installed above the flood level of the fixture.

Dual-flush WC: small flush about 3 litres, full flush about 5–6 litres; a single-flush older WC may use 9–12 litres and should be replaced for water saving.

Basin and sink aerators restrict flow, commonly to about 6 litres per minute; clogged screens reduce flow and are cleaned or replaced.

Storage water heater thermostat is often set to 60°C to control Legionella; a thermostatic mixing valve then limits delivery to about 50°C at the outlet.

A temperature-and-pressure relief valve must be fitted to a storage heater and piped to a safe discharge; never cap, plug or block it.

A closed water heater system needs an expansion tank or expansion valve to absorb the volume increase when water is heated.

Sacrificial anode rods protect the steel tank lining; they are inspected and replaced when consumed, especially in hard-water areas.

Floor drains and infrequently used fixtures need trap primers or regular refilling to keep the water seal and prevent sewer odour.

Flexible appliance connectors should be braided stainless steel, not plain rubber, and should be accessible for inspection and replacement.

Solar water heating uses a collector and insulated storage tank; a heat-exchanger or drain-back system protects against freezing and scaling.

Drawing types: plan shows layout from above, elevation shows height, section shows cut-through levels, and isometric shows pipe routes in three dimensions.

Scale 1:50 means one drawing unit represents 50 real units; 1:100 means one unit represents 100, so check the scale before scaling a dimension.

Invert level is the inside bottom of a pipe; cover level is the top of the ground or chamber; the difference gives depth and the fall between points.

Measurement units: pipes in running metres, fittings and fixtures in numbers, excavation and concrete in cubic metres, and formwork in square metres.

Take-off requires pipe lengths plus fittings, valves and supports; add wastage, commonly 5–10% depending on material and complexity.

Rate analysis = material cost + labour cost + tools and plant + overheads + contractor profit + applicable GST.

A bill of quantities lists items with description, unit, quantity and rate; the abstract totals the amounts to give the estimated cost.

Contingency of about 3–5% is added to estimates for unforeseen site work and price variation.

Plumbing estimate check: water demand and fixture units must agree with the tank, main and meter sizes shown on the drawing.

Hydrostatic test: fill the system, vent trapped air, pressurize to 1.5 times working pressure (or the specified test pressure), hold for one hour, and check for pressure drop and visible leaks.

Drainage water test: seal the lower end, fill to about 1.5 m head, hold 30 minutes, and inspect all joints; smoke and air tests locate faults in vent and drain lines.

Leak isolation: close section valves to divide the system, watch the pressure gauge, use dye or acoustic listening, and expose the suspected joint only after isolating and draining.

Low water flow at a fixture is traced in order: aerator screen, angle valve, flexible connector, scale in pipe, then pressure reducing valve or mains pressure.

Water hammer is caused by rapid valve closure, pump stop, loose pipe or missing arrestor; fix by clamping, fitting an arrestor and reducing velocity.

No hot water from a storage heater: check power supply, thermostat setting, heating element, dip tube and, for gas, the pilot or burner.

Sewer odour in a bathroom usually means a dry trap, blocked vent, cracked pipe or missing trap; refill the trap and test the vent before sealing the wall.

Pump short cycling is commonly caused by a waterlogged pressure tank, faulty pressure switch or leaking check valve; check air charge and switch settings.

Descaling of hot-water parts uses a weak citric or acetic acid solution, followed by thorough flushing; avoid strong acid on aluminium or zinc surfaces.

A quotation states scope of work, exclusions, price, GST, payment terms, completion time and validity; an accepted quotation becomes the work order.

A change order records extra or omitted work, revised price and time effect; get it signed before doing the changed work.

GST tax invoice essentials: supplier GSTIN, invoice number and date, recipient details, HSN or SAC code, taxable value, tax rate, and CGST/SGST or IGST.

Break-even quantity = fixed cost ÷ (selling price per unit − variable cost per unit); it shows the job volume needed to cover costs.

Cash-flow control: bill stage payments, keep material and labour records, and follow up receivables so that the next job can be financed.

Customer complaint handling sequence: listen without interruption, acknowledge the problem, inspect and explain, agree a remedy, complete it, and follow up.

Employability records include resume, trade certificate, safety training, work samples and references; keep them current and truthful.

Warranty covers defects in workmanship or material for a stated period; guarantee is a broader promise, and both should be written into the contract.

Statutory compliance for a plumbing enterprise includes GST registration when liable, labour welfare and safety duties, and proper bills and wage records.

Rainwater harvest yield in litres = catchment area (m²) × rainfall (mm) × runoff coefficient; 1 mm of rain on 1 m² gives 1 litre.

Typical runoff coefficients: concrete roof 0.8–0.9, tiled roof 0.6–0.8, bare soil 0.3–0.5; use a lower value for rough or absorbent surfaces.

A first-flush diverter discards the initial roof runoff carrying dust and bird droppings; it is sized from roof area and expected rainfall.

Low-flow fixtures: dual-flush WC 3/5 L, aerated basin tap about 6 L/min, waterless urinal, and drip irrigation instead of hose watering.

Greywater from baths, basins and laundry can be treated for flushing and subsurface irrigation; it is not used for drinking, cooking or direct food contact.

Solar water heater and heat-pump water heater reduce electricity use; insulate hot-water pipes and avoid long uninsulated dead legs.

A water audit compares metered supply with fixture and process use, then ranks leaks, overflows and inefficient fixtures for repair.

Fix leaks promptly: a dripping tap or leaking float valve can waste hundreds of litres per day and increase the water bill.

Rainwater storage tanks need a screen, first-flush inlet, overflow, and mosquito-proof cover; water for potable use needs filtration and disinfection.