D1, Manifold and Tundish
Build the first discharge stage from relief valve through correctly sized D1 or approved manifold to a visible tundish with the required air break.
Prepare from system boundary to safe handover
Learn the safety chain, practise source-led design and fault decisions, and rehearse every live task with an approved centre or competent supervisor.
Core concepts
Concept 1
Build the first discharge stage from relief valve through correctly sized D1 or approved manifold to a visible tundish with the required air break.
Exam cue: Identify every valve, verify outlet and D1 size, confirm any manifold is part of the approved arrangement, then place the tundish vertically, close to and below the device.
Concept 2
In England guidance, D1 is metal and not smaller than the safety-device outlet; the tundish is in the same space and no more than 600 mm of pipe from the valve outlet.
Exam cue: Fix the work nation, product instructions, energy state and practical-authority boundary before choosing an action.
Concept 3
The tundish makes discharge visible and incorporates an air gap; it is not a trap or a device that makes an unsafe downstream route acceptable.
Concept 4
Other UK nations publish their own distances and wording; apply the current local document rather than copying England dimensions automatically.
Targeted study blocks
Purpose
Know the safety outcome
Build the first discharge stage from relief valve through correctly sized D1 or approved manifold to a visible tundish with the required air break.
Method
Use a repeatable evidence sequence
Identify every valve, verify outlet and D1 size, confirm any manifold is part of the approved arrangement, then place the tundish vertically, close to and below the device.
Boundary
Stop at the product, legal and competence limit
Other UK nations publish their own distances and wording; apply the current local document rather than copying England dimensions automatically. Do not combine discharges through an improvised manifold or position the tundish where an occupier cannot see a warning discharge.
Risk pitfalls and guardrails
Do not combine discharges through an improvised manifold or position the tundish where an occupier cannot see a warning discharge.
Guardrail: Never bypass a safety device, cap a discharge or apply one nation's dimensions without checking the current local source.
Never cap a safety discharge, bypass an independent control or substitute written revision for supervised practical competence.
Guardrail: Never bypass a safety device, cap a discharge or apply one nation's dimensions without checking the current local source.
Memory anchors
D1, Manifold and Tundish: core
Build the first discharge stage from relief valve through correctly sized D1 or approved manifold to a visible tundish with the required air break.
D1, Manifold and Tundish: method
Identify every valve, verify outlet and D1 size, confirm any manifold is part of the approved arrangement, then place the tundish vertically, close to and below the device.
D1, Manifold and Tundish: key fact 1
In England guidance, D1 is metal and not smaller than the safety-device outlet; the tundish is in the same space and no more than 600 mm of pipe from the valve outlet.
D1, Manifold and Tundish: key fact 2
The tundish makes discharge visible and incorporates an air gap; it is not a trap or a device that makes an unsafe downstream route acceptable.
D1, Manifold and Tundish: boundary
Other UK nations publish their own distances and wording; apply the current local document rather than copying England dimensions automatically.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
In England guidance, what is D1?
What material does current England guidance specify for D1?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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