Gas and gas flow cells

Scope

This experimental work instruction applies to experiments using gas and gas flow cells.

Pre-visit

The User Principal Investigator shall provide the following to the Diamond Local Contact at least eight weeks prior to the experiment at Diamond:

• Essential Information Requirements (see below).

Assurances that user-provided equipment achieves the relevant:

• Essential Safety Requirements (see below).

Assurances that users coming to Diamond achieve the relevant:

• Essential Safety Requirements (see below).

Assurances that the equipment is compliant with the safety requirements of the home institution.

Diamond Local Contact shall ensure compliance with the following for Diamond provided equipment:

• Essential Information Requirements (see below)
• Essential Safety Requirements (see below)
• Essential Competency Requirements (see below)

 Pre-experiment

Diamond Local Contact shall ensure that the above pre-visit requirements for User provided equipment is reviewed by a competent technician or engineer. This shall include inspection of the equipment.

 Experimental Setup

Diamond Local Contact and User Visit Principal Investigator shall collaborate to ensure adherence to:

• Essential Experimental Setup Checklist (see below).

 Operation

Diamond Local Contact and User Visit Principal Investigator shall collaborate to ensure adherence to:

• Essential Operational Checklist (see below).

 

Essential Safety Requirements

Equipment shall be:

• rated and compatible for the intended pressure, temperatures, substances, flow rate, sample environment and setup conditions at Diamond
• suitably tested by a competent person or body to ensure safe operation at Diamond. Non-standard set-ups shall be commissioned and tested prior to coming to Diamond
• safely packaged and transported to Diamond to prevent damage that could affect safe operation
• suitably risk assessed, identifying failure modes, safety controls and emergency controls (ref Essential Hazard and Failure Mode Checklist)
• fitted with suitable safety devices (eg, flow restrictor specific to the sample environment/gas)
• labelling: equipment CE/UKCA marked or has an appropriate declaration of conformity
• remote operation enabled as far as possible
• local exhaust ventilation (LEV) is suitable and tested for the gases used in the experiment (check LEV logbook)

 

Essential information requirements

Information required:

• a full description of the proposed experimental setup and technical specifications
• reagent details including gas name, gas purity/grade, volume, etc
• sample environment details including pressure, flow rate, temperature range, possible unsafe reactions, conditions, by-products, etc
• safe operating procedure/instructions for any equipment not provided by Diamond
• unique Identification mark of any equipment not provided by Diamond, ie, its serial number
• assurances and evidence of adequate pressure testing for pressure cells (where applicable)
• assurances and evidence that all equipment has full up-to-date test and calibration certificates (where applicable)

 

Essential competency requirements

Person setting up experimental equipment shall:

• have sufficient experience of setup, test and operation of the equipment, gases, risks and required safety controls to ensure safe setup
• have sufficient skills and be practiced in the setup and operation of the equipment, gases, risks and required safety controls used in the experiment
• have sufficient knowledge of the essential safety requirements of the equipment to ensure safe setup

Persons operating equipment shall:

• have sufficient experience and be practiced in safe use of the specific equipment, gases and required safety controls to ensure safe operation
• have sufficient skills and be practiced in safe use of the specific equipment, gases and required safety controls used in the experiment
• have sufficient knowledge of the essential equipment safety requirements, gases, and safety controls to ensure safe operation. This includes knowing when to stop operations and what to do in the case of an emergency
• be suitably supervised if they do not have sufficient skills, knowledge, and experience

 

Essential experimental setup checklist

• Persons setting up the equipment meet the Essential Competency Requirements.
• Guarding: components which could fragment under pressure are sufficiently guarded.
• Compatibility: the gas lines and components are compatible with the substances to be used.
• Component ratings are suitable for the working pressures. Components are correctly rated for the conditions, materials and temperatures that will be experienced.
• Gas regulators/pressure gauges/valves are the correct type for the gas in use, within test date, in good condition and installed correctly (with the correct grade of hose).
• Gas cylinders (where installed) are in-date, of the correct grade gas, and appropriately supported (stand, trolley or chained / strapped to the right size bracket).
• Pressure relief systems are in place, functional, and set to relieve at reasonable pressures. These systems release to a safe place away from people.
• Gas monitoring is in place and functional (where hazardous gases used).
• Joints are mechanical only with no use of adhesives / sealants unless this is unavoidable and then they must be of a type compatible with the gas(es) in use.
• Purging: The system has been purged of previous substances.
• Pressure setting: The pressure is set to the lowest level practical for the experiment.
• Flow controller(s)/restrictor(s) are installed and set to lowest practical flow rate for the experiment (and with a maximum limited to 100SCCM).
• Leak testing: The assembled system has been adequately leak-tested (eg, with inert gas – helium, holding a constant flow of 150and of the desired flow).

Use of harmful gases must not be allowed until leak test is completed and all personnel left the area and hutch doors are closed.

• Remote shutdown is enabled for all experimental equipment. 
• Visual inspection of the setup.
• Manufacturer’s instructions (where applicable) have been followed during setting up.
• Labelling: gas/air lines and connectors (where applicable) are clearly and correctly labelled. Signs are placed outside the hutch to indicate which gases are present and what the associated hazards are.
• Modifications from planned setup have been checked by a competent person.
• LEV: local exhaust ventilation is functioning, is within date (green label), and correctly positioned. Exhaust lines must be at least 30 cm into LEV.
• Exhausts are open and cannot lead to pressurisation of the system.

 

Essential operation checklist

• Persons operating the equipment meet the Essential Competency Requirements.
• Visual check of the setup is carried out before every operation.
• Modifications to the planned setup are done by a competent person and checked against the Essential Experimental Setup Checklist.
• Safety controls stated in the User Experimental Risk Assessment (ERA or lab form) are applied, and the ERA has been graded and validated.
• Safety controls stated in both the beamline risk assessment and any Diamond equipment risk assessment are applied. 
• Lone-working prohibition is in place and understood by all persons supervising the experiment.
• Suitable supervision of the experiment is in place to ensure safety.
• Failure modes of the set-up are understood by all persons supervising the experiment.
• PPE identified on the risk assessment is provided; it fits, it is in good condition, and all operators are proficient in its correct usage.
• Emergency conditions and required action is understood by all persons supervising the experiment.
• Emergency actions on a gas leak during the experiment, the set-up/preparation (including peripheral lab use) have been written (identifying the foreseeable emergencies) and are understood by all persons supervising the experiment.
• Emergency action on the fire alarm sounding is understood by all persons supervising the experiment.
• Emergency action on gas detection sounding is understood by all persons supervising the experiment.
• Emergency action on power outage is understood by all persons supervising the experiment.
• If safety issues are identified, the Principal Beamline Scientist (PBS) must be contacted, and the issues resolved before continuing with the experiment.

 

Essential hazard and failure mode checklist

The main hazards are:

• exposure to hazardous substances resulting from uncontrolled release of hazardous or flammable gases
• exposure to hazardous substances resulting from slow leak of hazardous or flammable gases
• exposure to hazardous substances resulting from inadequate leak testing
• exposure to hazardous substances resulting from incorrect gas delivery or mixing
• exposure to hazardous substances resulting from failure of joints, disconnection, breakage of capillary tube, sample environment equipment
• exposure to hazardous substances resulting from inadequate exhaust setup (eg, exhaust line falling out of LEV trunking)
• over-pressurisation resulting from blocked outlets or incorrect setup
• hot surface contact (if applicable)
• fire resulting from overheating of equipment or heating elements (if applicable)
• fire resulting from release of flammable gas
• incompatibilities resulting from failure of gas lines or components due to incompatibility with gas or liquids

Principal failure modes are:

• poor equipment or system design
• poor installation or setup
• poor maintenance of equipment
• inadequate repairs or modifications
• an unsafe system of work
• operator error, poor training or supervision

 

Flow cell and hazardous gas beamline emergency response

Gas alarm types

• Oxygen depletion alarms activate when oxygen level goes below 19.5and volume.
• Flammable gas alarms activate at 10-20and of the lower explosive level (LEL) for the gas.
• Hazardous gas alarms vary but typically activate at a percentage of the workplace exposure level (WEL) for the specific gas:
  • low alarm: typically set at around 10and of the WEL – this is an early warning level that there is low-level gas leakage)
  • high alarm: typically set around 20and to 25and of the WEL – this is an action level to prompt evacuation)
• It is important that all persons are aware of the significance of the different alarm types, their sounds, and the actions required on sounding.
• For information on portable alarms, check with EHCs when alarms are issued.

Response on gas alarm or uncontrolled gas release

• Keep the beamline closed and do not try to enter.
• Make safe: isolate the gas supply. This should be done from outside the beamline hutch and cabin.
• Exclusion: evacuate the control cabin and the immediate area around the beamline hutch and cabin as a precaution.
• Pause and assess the situation; develop an action plan. Call EHCs (8787) for support.
• Monitor: use gas detection equipment to monitor the concentration of the hazardous gas in the area.
• Re-entry: wait until the alarms have stopped, and then another 15 minutes before re-entering (or a minimum of 90 minutes as calculated per CAS24 1214 10 1001 Issue 3). Take specific portable gas monitor with you.

Breakage of active capillary tube

• If gas is flowing:
  • treat as uncontrolled release of gas
• If gas is not flowing:
  • do not attempt to repair the capillary tube unless you are trained and it is safe to do so
  • wear laboratory gloves and treat capillary tube as sharps waste
  • clean and decontaminate the sample-environment area of all debris and powders. Dispose of hazardous powders and contaminated wipes as hazardous waste

Incident reporting

• Inform Principal Beamline Scientist at the earliest opportunity.
• Local Contact or EHC to submit a Diamond Incident Report.