Page 312 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

The City & Guilds Textbook: Plumbing Book 1

Type AUK2 air gaps for taps and combination fittings
(tap gaps) discharging over domestic sanitary appliances

This refers to the height of the air gap between the lowest part of the outlet
of a tap, combination fitting, showerhead or other fitting discharging over a
domestic sanitary appliance or other receptacle, and the spill-over level of that
appliance, where a fluid category 2 or 3 risk is present downstream. An AUK2
air gap is suitable only for back siphonage up to fluid category 3 and must
comply with the distances stated in Table 5.7.

Washbasin cold water pillar tap
connected to fluid category 1

AUK2 air gap

Washbasin - fluid category 3

Suitable for protection against fluid category:
Back Back
X pressure 3 siphonage
p Figure 5.71 AUK2 air gap (tap gaps)

AUK3 air gaps for taps or combination fittings (tap gaps)
discharging over any higher-risk domestic sanitary
appliances where a fluid category 4 or 5 is present

Type AUK3 – higher-risk tap gap means the height of an air gap between the
lowest part of the outlet of a tap, combination fitting, showerhead or other
fitting discharging over any appliance or other receptacle, and the spill-over
level of that appliance, where a fluid category 4 or 5 risk is present downstream.

Lowest point of outlet of tap
Tap gap for sinks or appliances where a
higher degree of protection is required
should be type AUK3

Spill-over level
Sink or higher-risk appliance

Suitable for protection against fluid category: Cold water supply
Back Back Hot water supply
X pressure 5 siphonage

p Figure 5.72 AUK3 air gap (higher-risk tap gaps)

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