Gas Cylinder Manifold Spares

In many laboratory applications gases from cylinders or insulated liquid tanks are piped via static systems to the point of use. From a safety perspective this can eliminate free-standing cylinders in the workplace, avoid the requirement for difficult cylinder handling operations and generally cut down on the number of cylinder handling movements and the numbers of people involved in those movements as well as reducing the likelihood of running out of gas mid-process.

It is essential that the system is correctly installed and maintained and that the operators are correctly trained in its safe operation and actions to be taken in an emergency.

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  • Supply Items
  • Distribution Systems
  • Operation
  • Maintenance

The installation from the cylinder to the main pressure regulator must be gas compatible and capable of withstanding cylinder fill pressure.

From the cylinder valve, connection to the header is made by a 'pigtail' which may be flexible hose or tubing fitted with the appropriate valve specific connector. Each pigtail should have a non-return valve or isolating valve. The header is fed from the pigtail. This may incorporate purge points, isolation valves, bursting discs, heaters, vaporisers etc.

The pressure in the distribution system is controlled by a main regulator (typically two-stage unless the cylinder supply is low pressure from a liquefied supply such as propane). The main regulator is carried on a mounting block and should be positioned so that the operator can see the HP and LP gauges.

The specific components in a distribution system depend on the gas for which the system is designed. However, certain components are essential. For example, following the main regulator on the supply "the distribution system shall be protected against over-pressurisation resulting from regulator malfunction or other abnormal circumstance" (BCGA CP4). This can take the form of a pressure relief valve or bursting discs. It is a wise precaution to provide a piped vent away from the operator and the system (usually up the side of the building and not terminating near windows etc).

As the system enters a building there should be a main isolating valve and there should be isolation and non-return valves fitted to each outlet point on the bench or wall.

Instruction cards must be in place to indicate correct and safe operation of the system controls. It is good practice to have a system flow sheet available. Such information is provided by the supplier (usually the system installer). All operators must receive adequate training and instruction before operating manifolds and pipelines.

 

Note: Many installations have two banks of cylinders to feed the supply system; one in use, the other on reserve. Loss of pressure and/or flow will indicate when the cylinders need changing. Change-over can be achieved by having two regulators set at slightly different pressures, as one side empties the other automatically takes over. Alternatively, the system may have a manually or automatically operated change-over valve. Such equipment can be connected to a remote alarm panel which shows that change-over has occurred and the empty cylinders need to removed and replaced with full ones.

In the case of manually operated changeover the full cylinders on reserve can be connected but their valves must be left closed. As part of the changeover procedure they can be opened and the connections to them leak tested.

Weekly inspection (According to BCGA CP4) Each week check that:

  • the equipment looks to be in good order, is being used correctly and all necessary equipment is fitted
  • the manifold framework and chains are in good condition
  • the pigtails are in good condition
  • valves shut off and reopen correctly
  • the regulators are correctly identified for the gas(es) and pressure(s)
  • the system is operating normally and no defects have been reported
  • the manifold house is clean and is not being used as a general store

Annual inspection check that:

  • any repairs or modifications have been carried out in accordance with the appropriate code
  • any changes near the pipework do not affect operation or safety
  • the pipework is marked properly in yellow ochre and carries the name of the gas
  • the system is free from leaks by testing at designated operating pressure
  • the filters are in good condition and not blocked

Maintenance in accordance with the written scheme - contact us for more information.
© Gas Safety UK 2007