UPMSP High School Plumbing - Code 976 flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Class B fire

Fire involving flammable liquids such as petrol, kerosene, paint, or solvent; extinguish with foam, dry powder, or CO2, never with a water jet.

Trench shoring rule

Excavations deeper than 1.5 metres require shoring, sloping, or a trench box; keep excavated spoil at least 0.6 metre from the edge and provide a ladder for access.

Solvent cement hazard

PVC and CPVC solvent cements are flammable and give off harmful vapour; use only in a ventilated area, away from flame, with gloves and eye protection.

Pipe wrench jaw direction

The teeth of a pipe wrench must face the direction of handle rotation so the jaws bite; pulling the handle toward you tightens the grip on the pipe.

Hacksaw blade selection

Use 18 teeth per inch for thick-walled pipe and soft metal, and 24 teeth per inch for thin tube; fit the blade with teeth pointing forward.

Pipe cutter procedure

Square the cutter wheel to the pipe, tighten about a quarter turn per revolution, and ream the inside and outside burr after the cut to restore full bore.

45-degree offset formula

For a 45-degree offset, travel equals offset multiplied by 1.414; the offset equals travel multiplied by 0.707; mark both cut points on the pipe centre line.

Pipe cut length rule

Cut length equals the centre-to-centre distance between fittings minus the sum of the fitting take-outs; take-out is the face-to-centre dimension given by the manufacturer.

Vernier caliper least count

A common vernier caliper has a least count of 0.02 millimetre; close the jaws and check that the zero marks coincide before measuring a pipe or fitting.

BSPT thread taper

British Standard Pipe Taper threads have a taper of 1 in 16 and seal in the threads; wrap PTFE tape clockwise and leave two or three threads exposed after tightening.

CPVC hot water limit

Chlorinated polyvinyl chloride pipe is suitable for hot water up to about 93 degrees Celsius; join it with CPVC solvent cement and allow the recommended cure time before pressure testing.

HDPE butt fusion

HDPE pipe is joined by heating squared pipe ends on a hot plate and pressing them together; the bead formed must be even, and the joint cooled before handling.

Copper capillary soldering

Clean the copper tube and fitting to bright metal, apply flux, heat evenly, and feed lead-free solder into the joint; capillary action draws solder around the gap.

Per capita water demand

Indian domestic water supply is commonly designed at about 135 litres per capita per day; add allowance for commercial, institutional, fire, and leakage losses.

Static head to pressure

Pressure equals density times gravity times head; 10 metres of water head is approximately 1 bar or 100 kilopascals; use this to check tap pressure.

Centrifugal pump priming

A centrifugal pump must be filled with water before starting; a foot valve keeps the suction line primed, and running dry damages the seal and impeller.

Check valve function

A non-return or check valve allows flow in one direction only; it prevents backflow, protects the pump, and stops stored water draining back to the mains.

Trap water seal

The water seal in a trap stops sewer gas entering the building; a minimum seal of 50 millimetres is used, and the seal must be maintained by regular use.

Two-pipe drainage system

In a two-pipe system soil from water closets and waste from sinks and basins run in separate pipes; each has its own vent, reducing cross-contamination and siphonage.

Self-cleansing velocity

Drain pipes should carry flow at about 0.6 metre per second or more to keep solids moving; excessive velocity above about 3 metres per second scours and noise.

Gully trap location

A gully trap is placed at the junction where kitchen, bath, or floor waste enters the drain; it holds a water seal and is accessible through a grating for cleaning.

Gate valve symbol

On plumbing drawings a gate valve is shown as two triangles meeting at their points, like a bow tie, placed on the pipe line with the flow direction indicated.

Isometric plumbing sketch

An isometric sketch uses three axes drawn at 30 degrees to the horizontal; pipe runs are shown parallel to these axes, giving a three-dimensional view of the layout.

Drawing scale 1 to 50

A scale of 1 to 50 means one unit on the drawing represents 50 units on site; measure the drawing and multiply by 50 to obtain the real dimension.

Hydrostatic pressure test

Fill the water supply pipe with water, raise pressure to 1.5 times the working pressure, hold for one hour, and check for leaks and gauge drop.

Drain air test

For a drain air test, seal the ends, apply about 100 millimetres of water gauge air pressure, and check that the pressure holds for at least five minutes.

Leak detection by sound

Water escaping from a buried pipe creates a noise; use a listening stick, stethoscope, or acoustic logger at night when background noise is low to locate the leak.

Running metre measurement

Pipes are measured in running metres along their centre line, excluding fittings, which are counted separately in numbers; record size, class, and material in the description.

Rate analysis components

A rate analysis adds material cost, labour cost, equipment, overheads, and profit; add applicable GST and wastage to obtain the final unit rate.

Contingency allowance

Add about five to ten per cent of the estimated cost as contingency for unforeseen work, price rise, and minor changes; keep it separate from measured quantities.

Break-even quantity

Break-even quantity equals fixed cost divided by the difference between selling price per unit and variable cost per unit; below this quantity the business makes a loss.

GST invoice essentials

A tax invoice must show supplier GSTIN, unique invoice number and date, customer details, description and HSN or SAC code, taxable value, GST rate, and amount.