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Sanitation

Exam revision materials for Plumbing Level 2&3 and ACS Gas Safety test

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Sanitary Pipework Systems

Pipework Requirements

Stack System

  • MIN 75mm (82mm actual pipe size) to connect WC<80mm (only 1 WC) and for a drainage pipe
  • MIN 100mm (110mm actual pipe size) to connect WC>80mm or those discharging soil waste
  • MIN 450mm from the invert to the lowest brunch connection
  • MIN 200mm invert bend Ø 
  • No brunches within 750mm of the offset
  • Stack System
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Stack Vent

  • the pipe size can be reduced down to 75mm in houses of 2 stores or less

  • MIN 900mm termination above the opening if <3m away from it (window)
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Intumescent Fire Collar

  • Purpose - preventing spreading of fire by blocking the pipe end with graphite filler when heat has been applied
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Strap-on boss connector

  • Strap-on boss connection to soil stack makes by a hole saw
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Branches to Primary Ventilated Stack

  • MIN 500mm between bath/shower and basin connection which is fitted with Resealing Trap

Appliance

MIN pipe size

MAX length

MIN Gradient

MAX con.

WC>80mm

100 (7.2L/sec.)

6.0

18-90

8

WC<80mm

75 (3.4L/sec.)

6.0

18-90

1

Washbasin or Bidet

32

1.7

18-90

3

Sinks & Baths; washing machine;

kitchen sink; sink macerator

40

3.0

18-90

 

Sinks & Baths

50 (1.2L/sec.)

4.0

18-90

 

Urinal

50

3.0

18-90

 

WC (outlet > 100mm) and >1 WC is connected

-

-

9

 

Stack System
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Waste Pipe Materials

  • Cast iron​
    • 1.8m – standard length
    • Lengths of pipe are joined by Yarning and Caulking (except rainwater down-pipes)
    • Centrifugal cast pipes fixed using Holderbat Clips
  • Plastic
    • Polypropylene (withstand high temp.; no solvent; used for traps)
    • Polyvinyl chloride (PVC or uPVC; brittle when cold)
    • Acrylonitrile butadiene styrene (ABS; stronger when cold; withstand high temp. for long)
    • Polyethylene (no solvent)
  • Borosilicate Glass – used in laboratories; minimal thermal expansion
  • Copper Tube sanitary pipework can be joined by Bronze Welding
  • McGuires Rule – formula to work out the correct fall of drain pipe
    • 100mm diameter pipe when laid to a gradient of 1 in 40 will give a discharge of approximately 1.14 metres per second, when flowing at 1/3 full
  • The MIN  Stack Vent size on 110mm PVSS to a two-storey dwelling is 75mm
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Discharging Requirements

  • Brunch Pipe SHOULD NOT discharge into open hoppers
    • Any pipe CAN discharge into:
      • Stub Stack / Discharge Stack
      • Directly to a drain
    • Waste water pipe CAN discharge to a gully
      • Brunch pipe SHOULD terminate between the grating and top of the water seal
  • Direct Connection to a Drain:
    • WCs Brunch Pipe on the ground floor SHOULD only be connected to a drain if the MAX depth from the floor to the drain is 1.3m
  • 100mm branch connection to a discharge stack MUST have MIN bend radius of 50mm
Waste pipework
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