Siting Manifolds

The following guidance notes are extracts from information published by the BGCA in its Codes CP4 and CP7 and by the LPGA in Codes of Practice numbers 1 and 7. The notes are intended for checking the feasibility of new manifold installations. Any actual installations should be planned and executed by experts working to the above Codes. Any case of conflict, the Codes shall take precedence over these notes.

Safety distances

Manifolds and their associated regulators and valves should, where practical, be sited outdoors or in a manifold room which conforms to the following safety requirements and is used solely for housing manifolds. The manifold must be sited so that it is separated by a specified safety distance from features which cause a risk.

The following links take you to the safety distances tables for: -

Acetylene Manifolds

Oxygen or inert gas manifolds

Flammable gas or LPG cylinder manifolds

Cryogenic oxygen or inert gas storgae tanks

How to use the safe distance tables

The figures in the table are all minimum distances measured from any point on the system where in normal operation leakage can occur (such as connection points). Where the require distance cannot be achieved in a horizontal plane, fire resistant walls to a height of 2.5 metres should be used. The safety distance may then be measured as the shortest distance around the ends of the wall to the installation.

Manifold rooms

Where a manifold is to be sited indoors it should be in a specially constructed building or in an established building which conforms to the following safety requirements: -

Design

All walls of the manifold room (excepting those for inert gases) should be constructed of fire resisting material BS 476 (33) and the floor of concrete or other inorganic material.
Manifolds installed in an existing building shall be separated from the rest of the building by a wall built to roof level and one wall shall be an outside wall.

Access

An access door designed to allow easy level access for cylinder movement.
Ideally, a second emergency escape door.
One of the doors should be on the outside wall.
All doors should open outwards and should not be self locking

Ventilation

Ideally, two sides of the room should be open, preferably opposite sides.
It is acceptable practice to have one wall in wire mesh incorporating the entrance doors and to have high and low ventilation in the opposite wall.
Where the room is part of an existing building, the ventilation must not be into the building.
The room should be well ventilated to prevent the build up of gases where an asphyxiant, flammable or oxygen enriched atmosphere could occur.
The roof must be designed to prevent build up of lighter than air gases (where used) with ventilation at the highest point.

Exceptions

There are circumstances where it may be acceptable to position manifolds inside buildings, e.g. large fabrication shops where the volume of the building is such that there is no possibility of an asphyxiant or oxygen enriched atmosphere occurring. A risk assessment is necessary before proceeding with such an installation – see CP 4.

For more information on the storage of cylinders please call BOC on 0800 111 333 and order a copy of Safe Under Pressure (SFT/007875).