Risk Assessment and PPE Selection
The assessment
Five steps: identify the hazards, decide who may be harmed and how, evaluate the risks and decide on controls, record the significant findings, and review and update. It must be task-specific, completed before work starts, and reviewed whenever the task, the equipment, the people or the environment change. A site induction or a generic method statement is not a risk assessment.
The hierarchy of control
Eliminate the hazard, substitute something safer (a lower-GWP or lower-pressure refrigerant, a factory-sealed unit), apply engineering controls (ventilation, fixed gas detection, guarding, mechanical lifting), then administrative controls (permits, procedures, training, supervision), and only then PPE. PPE protects the individual; it does not reduce the hazard and must never be the primary control.
Typical PPE for this work
Chemical splash goggles plus a face shield when coupling hoses or charging; low-temperature gloves that are loose enough to pull off if liquid gets inside; safety footwear; hearing protection in plant rooms; a calibrated refrigerant detector; respiratory protection for ammonia; flame-retardant coveralls and a hot-work permit for brazing.
Traps
- A question that offers PPE as the first or only control is almost always wrong.
- Jewellery, watches and rings trap liquid refrigerant against skin.
- Lone working, emergency arrangements and rescue plans are frequently forgotten.
- The assessment is not "done once" - it is reviewed.
Worked example
Recovering 12 kg of R-404A from a rooftop condensing unit: obtain access and permit, isolate and lock off, assess wind and weather, barricade the area below, don PPE, set the recovery machine and correctly rated cylinder on scales, and check oxygen level and refrigerant concentration before and during the work.
Leak Checking, Containment, Records and Reporting
Frequency thresholds
Leak checks are triggered by tonnes CO2e, not by charge weight: 5 t or more - every 12 months; 50 t or more - every 6 months; 500 t or more - every 3 months. Each frequency halves (24, 12 and 6 months) where a fixed leak detection system is installed and verified, and that detection system must itself be checked at least every 12 months. Hermetically sealed, factory-labelled equipment below 10 t CO2e is exempt from periodic checks, but leaks found must still be repaired.
Methods
Direct methods include an electronic detector, soap solution, UV dye and standing vacuum tests. Indirect methods include F-gas monitoring, pressure and performance checks, and visual inspection for oil traces. A confirmed leak must be repaired as soon as practicable - normally within 14 days - and a follow-up check must verify the repair within one month.
Records
Records are kept by the operator for at least five years and must show: the refrigerant type and quantity, quantities added and recovered, the date and result of every leak check, and the name, certificate number and company of the person who did the work. They must be produced on request to the regulator.
Traps
- Using kilograms instead of CO2e to decide frequency.
- Forgetting that verifying the leak detection system is a separate annual task.
- Records showing repeated top-ups with no leak check in between - a classic enforcement trigger.
- Assuming there is no reporting duty: records must be available for inspection, and company certification and waste transfer notes must be traceable.
Worked example
20 kg of R-407C (GWP 1774) = 35.5 t CO2e. That is above 5 t and below 50 t, so quarterly checks are not required: 12-monthly, or 24-monthly with a verified fixed detection system.
Installation, Commissioning, Pressure Testing and Evacuation
Pressure testing
Use oxygen-free nitrogen (OFN) only, fed through a regulator, with the system isolated and relief devices protected. Never use oxygen, compressed air or refrigerant to pressure-test: oxygen plus oil can explode, and testing with refrigerant proves nothing while creating a release. Test to the pressure specified by the manufacturer or system design - commonly 1.0 times the maximum allowable pressure for a tightness test - allow the pressure to stabilise, and record the pressure alongside the ambient temperature so you can correct for temperature drift before declaring a leak.
Evacuation and dehydration
Evacuate with a two-stage vacuum pump and read the vacuum at the furthest point with an electronic vacuum gauge, not with manifold gauges. A typical target is 500 microns (about 0.67 mbar) absolute, held for a decay test; a triple evacuation with nitrogen breaks is the reliable way to remove moisture. A vacuum that holds demonstrates dryness and gross tightness - it is not a substitute for the pressure test.
Charging and commissioning
Charge by weight from scales. Zeotropic blends such as R-407C and R-404A must be charged as liquid, because vapour charging fractionates the blend and shifts its composition and performance. Record the OFN test, the vacuum results, the final charge, and all control settings.
Traps
- Using refrigerant to "blow through" or pressure-test a system.
- Reading vacuum from manifold gauges - they are not accurate enough.
- Vapour-charging a zeotropic blend.
- Condemning a system as leaking when the overnight pressure drop was simply a fall in ambient temperature.
Rule of thumb
A pressure that varies with temperature is not evidence of a leak; a pressure that keeps falling after correcting to a reference temperature is.
Servicing, Recovery, Recycling and Decommissioning
Service work
Leak check before and after the work. Recover the charge to a dedicated cylinder before breaking into the circuit, replace filter driers whenever the system is opened, purge with OFN while brazing, evacuate, recharge by weight, and update the record. Never simply top up a system to "get it running" - the leak still has to be found and repaired.
Recovery
Recover into an evacuated, weighed, dedicated cylinder using a recovery machine, or push-pull for large charges. Do not exceed the 80% liquid fill limit, and use the machine's final pull-down stage to remove residual vapour. Recovery is mandatory for every F-gas and ODS before the circuit is opened or the equipment is dismantled or scrapped. Venting is prohibited.
Recycling versus reclaiming
Recycling is cleaning recovered refrigerant by separating oil and moisture, suitable for reuse - normally in the same equipment or by the same owner. Reclaiming is reprocessing to a published specification with laboratory analysis, and only reclaimed refrigerant may be used in another owner's equipment or sold on. Recovered ODS such as R-22 can only be destroyed.
Decommissioning
Recover all refrigerant and record the quantity, cap or remove components, send the equipment for WEEE-compliant disposal, and give the operator a decommissioning record. Label every cylinder of recovered or contaminated gas with the refrigerant, quantity, date and its waste status.
Traps
- Calling a filtered recovery "reclaimed".
- Mixing gases in one cylinder.
- Assuming a small system may be vented.
- Forgetting the waste transfer documentation for recovered gas.
Worked example
A 30 kg R-410A chiller: required cylinder liquid capacity is 30 ÷ 0.8 = 37.5 kg, so at least three 15 kg cylinders are needed.