01/10/2014
User instruction for handling of gases and gas cylinders
Background
A risk assessment must be carried out for all operations where gas is handled. The requirement for this can be
found in Chapter 3, Section 2a of the Work Environment Act, where the employer is obliged to regularly
examine risks involved in activities and undertake action as a consequence of this.
Regulations on risk assessment can be found in the Swedish Work Environment Authority's regulations on
Systematic work environment management (AFS 2001:01) and Chemical work environment risks (AFS
2011:19).
As regards regulations concerning gases and gas cylinders in laboratories, these rules can be found in the
Swedish Work Environment Authority's regulations Gases (AFS 1997:7) and Gas cylinders (AFS 2001:04).
All National Board of Occupational Safety and Health regulations are available online at www.av.se
Risk assessment
A form with instructions which can be found on the university's intranet is best used for carrying out a risk
assessment.
To be able to carry out a risk assessment, it is necessary first to identify the risk sources present. These may
include hazardous substances or substances which are hazardous to health, electrical devices, pressure-bearing
devices, staff hired temporarily or a lack of necessary training.
It is important to assess the likelihood of the risk source being handled or working in an unwanted manner,
and to try to estimate the potential consequences of a fault. Finally, an evaluation is carried out which
establishes whether the risks are acceptable or whether preventive measures must be put in place, see e.g.
Gases AFS 1997:7.
Gases
There are currently 8 gases distributed to the outlet points via central pipe systems. These are hydrogen,
LPG, helium, nitrogen, argon, carbon dioxide, oxygen and compressed air.
There are monitoring systems for hydrogen, LPG, helium, nitrogen, carbon dioxide, oxygen and argon
which record gas consumption and monitor the consumption of hydrogen and LPG to ensure that these do
not exceed the maximum permitted instantaneous flows. If this happens, or if the power to the building is
cut, the distribution of hydrogen and LPG is shut off automatically. The distribution of hydrogen and LPG
cannot then be resumed until staff at the chemicals store have restarted the monitoring system centrally
once the cause of the problem has been located and rectified. Local key switches must then be activated in
order to open the gas distribution to each individual lab.
The Chemistry Building also has supplementary interlock which shuts off the distribution of hydrogen and
LPG if the central ventilation fan stops. Restarting takes place in the manner described above.
Besides the gases distributed centrally, there may be a requirement for other gases in order to meet special
requirements. These gases must then be provided by placing a gas cylinder at or next to the point where it is
required.
Due to the risks involved with gas cylinders during transportation and in the event of a fire, it is extremely
important to ensure that only a small number of gas cylinders is kept within the building, and that these
cylinders are as small as possible.
The user is responsible for acquiring product information which contains details about physical, chemical and
biological data for the gas, information on the risk of fire or explosion, special properties and risks, and
general instructions and material recommendations.
01/10/2014
This product information must be readily accessible and near to the gas cylinder. Information must also be
provided there on the gas store in which the gas cylinder is to be stored when it is not in use. The user is
responsible for the handling of the gas in question, and for ensuring that a risk assessment is carried out and
documented before using the gas.
Equipment
For all the equipment connected together with outlet points for gas or gas cylinders, the material used must
comply with the gas supplier's own material recommendations. This is particularly important to check for any
part of the equipment that may be exposed to mixtures of different gases, or mixtures of gases and the ambient
atmosphere.
Equipment that may be subject to overpressure must be designed, installed and tested in accordance with this.
If the equipment includes safety valves to protect against impermissibly high overpressure, and the gas used has
particular risks or properties, it is necessary to check that the outlet line for the safety valves opens up in a
location which is acceptable from a safety standpoint.
If gases with different pressures are mixed in any equipment, it is necessary to protect outlet points and/or gas
cylinders from overflow by fitting non-return valves in the supply lines.
It is important for the equipment used to be sealed, as a leak to the atmosphere may present a risk factor and
also results in an initially high-quality gas rapidly being impaired on account of atmospheric influence.
Equipment which is not clean does of course also have an adverse impact on gases.
Safety
There must be a safe zone around outlet points for flammable gases with regard to electrical equipment not
protected against explosive environments. How large this zone is is described in the general classification plans
on the university's intranet in the document "Information documentation, handling of flammable products".
Safety zones around outlet points for LPG and hydrogen from the central gas network are described in the
general classification plans available on the university's intranet. Therefore, it is important to check whether the
safety zone is sufficient before you start using new flammable gases, and that you bear in mind the fact that the
safety zone starts from the nozzle of a gas outlet or safety valve.
Gas cylinders must be clearly signed and secured so that there is no risk of them tipping over or being
damaged by transport trolleys and suchlike. Here, it is important to bear in mind that in most instances gas
cylinders are much heavier than tables, for example, so simply attaching them to a table leg is not sufficient.
Instead, they must be secured to walls or other permanently mounted fittings.
Gas cylinders must always be stored in a designated gas store when not in use. If there is no gas store next to
the laboratory, cylinders are handed to the Chemicals Store. Always contact the Chemicals Store in the case
of longer interruptions in the use of gas. It is very important to store gas cylinders in the designated store as
gas cylinders heated in the event of a fire incident present such a major risk of explosion as to significantly
impede the efforts of the emergency services.
See also "Checklist for gas cylinders" available on the university's intranet.