HC004 – Working Safely with Hydrocarbon Refrigerants

HC004 – Working Safely with Hydrocarbon Refrigerants

It is assumed that you are fully competent in working with refrigerants and hold a current F-Gas certification therefore safe working procedures detailed in the following section are not a full account of F-Gas procedures, only focussing on the differences between working with HFC and Hydrocarbon refrigerants.

The general conditions that must be implemented include:

  • Work should be carried out in a well-ventilated area or outside.
  • Use of an additional ventilation fan should be adopted, this needs to be an Ex-N rated type.
  • A 3 Meter radius safe working zone should be maintained always.
  • Ensure no smoking or sources of ignition previously indicated are within the 3m zone.
  • Any switching of equipment used must be outside the 3m zone.
  • A Dry Powder or CO2 extinguisher must be readily available.
  • A HC detector should be used at ground level before and whilst work is carried out.
  • HFC detectors are not suitable and cannot be used with HC’s.
  • Cylinders should be stored outside within a locked cage at ground level.
  • No more than 70 kg or 5 cylinders can be stored within a building.
  • When transporting cylinders, a minimum of 2Kg Powder extinguishers is required.
  • A 10 kg HFC recovery cylinder will only hold 4.5 kg of Hydrocarbon refrigerant (45%).
  • Access systems initially using a line-tap valve to recover refrigerant and then braze in a Schrader valve for repair and servicing.

Hydrocarbon systems with a charge of up to 150g may be vented to outside, above ground level, and at least 2m from the building.

Recovery of HC’s is to be completed using a suitable HC recovery machine.

When recovering hydrocarbon refrigerants, a suitable HC flammable gas leak detector and HC recovery machine must be included in the risk assessment.

Do not mix HC’s with other refrigerants.

Ensure recovery cylinders are evacuated prior to filling to avoid mixing HC with air.

Do not overfill the cylinder – Remember HC fill ratio to HFC is 45%

Hot works following venting of HC

If the HC has been vented from the system, then a triple evacuation must be carried out prior to any brazing or un brazing.

Charge the system to 5 Bar with OFN then vent to outside, evacuate the system using a vacuum pump.

Repeat the above, and charge a third time with OFN, finally vent and leave the vent line open to the atmosphere whilst un brazing connections.

Hot works following recovery of HC’s

Following recovery allow the recovery machine to continue running for 5 minutes to pull a vacuum on the system.

  • Break the vacuum with OFN to a pressure of 0.1 Bar.
  • Release the pressure, leave the line open and un-braze the connections.
  • When re-brazing, the system must be purged with OFN, and ensure at least one access point is open to the atmosphere to prevent pressure build-up within the system.

Pressure Testing

Strength test pressure = 1.1 x Ps Tightness test pressure 1.0 x Ps.

When pressure testing a Heat Pump system, refer to the pressure testing standards in accordance with BS/EN 378 (1.43 x Ps)

Further guidance on repair and working on HC systems can be found in standard EN 378

System Evacuation

The switch on the vacuum pump cannot be used.

  • Ensure the pump is switched to the on position prior to connecting to any power.
  • Use an extension lead supplied from outside the 3m zone and switch on and off outside the working zone.
  • The pump must be sited in a well-ventilated area.

Charging HC refrigerants

  • Charge by weight with accurate scales (+/-1% accuracy).
  • Critically charged systems accuracy is usually +/- 5%.
  • Gauge lines should be evacuated or carefully purged prior to charging. Open and close cylinder valve before purging.
  • Cylinders can be placed in water of no more than 45oC to aid charging.