HC003 – Practical Tasks

HC003 – Practical Tasks

PPE

Before working with Hydrocarbon Refrigerants, you must ensure that the correct level of PPE is selected which include the following as a minimum:

  • Safety Gloves
  • Fire Resistant Safety Gloves (For brazing activities)
  • Eye Protection (Goggles)
  • Safety Shoes/Boots

Safe working exclusion zone/barrier

A 3-meter safe working zone must be established and if possible, signage must be placed to advise that only working persons are permitted to enter the safe working area during periods where work is being undertaken.

Any equipment within the 3-meter working zone must be isolated to prevent switching during the period when working with flammable refrigerants.

Basic Equipment Requirement’s:

  • 2kg Powder Fire Extinguisher
  • Suitable Hydrocarbon Leak Detector
  • Suitable Hydrocarbon Recovery Machine
  • Suitable Hydrocarbon Ex-Rated Fan
  • Recovery Bottle marked with Hydrocarbon Refrigerant type
  • Refrigerant Scales & LCD Scales for charging activities on small volume systems.
  • Suitable Manifold Set
  • 3-Meter Extension Lead (Where required).
  • Suitable Vacuum Pump (must only be switched for operation outside of the 3-meter safe working zone).
  • Brazing Equipment.

Adequate Ventilation:

Before commencing any works, we must first ensure that the safe working zine is adequately ventilated using an ex-rated fan motor to ensure that there is no sources of ignition. The fan must be switched from an electrical point located outside of the safe working area.

Monitoring

The work area must be monitored by a suitable hydrocarbon leak detector at all times during the work process.

Due to their density, hydrocarbon refrigerants accumulate at low levels therefore the leak detector must be placed at low level where it will pick up any trace of hydrocarbons released during the work process.

Recovery of Refrigerants:

Hydrocarbon refrigerants should only be recovered using a suitable hydrocarbon Recovery Machine. To facilitate safe recovery of hydrocarbon refrigerant from a system the following equipment is required:

Recovery Bottle marked with the refrigerant type making note of the bottle details including:

  • Actual Bottle Weight
  • Bottle Tare Weight (Empty Bottle Weight)
  • Bottle fill capacity. (Remember that a standard HFC recovery bottle should only be filled to 45% of the max fill weight stamped on the bottle neck)

By recording the bottle details, we can calculate to ensure that there is enough capacity in the bottle safely recover the refrigerant amount within the system.

Refrigerant Scales (Zero Scales before weighing recovery bottle)

Connection of Equipment:

Before any recovery works are undertaken, ensure that the system is fully isolated.

Connect both high side and low side lines are connected to the manifold and to both high and low sides of the system. Purge both lines at the manifold.

Connect the Auxiliary line (Yellow) to the IN port located on the recovery machine, open and close the manifold on the low side to enable purging at the recovery machine inlet port.

Place the recovery bottle on the refrigerant scales and connect an auxiliary line between the recovery machine outlet port n the recovery bottle inlet port.

Open the recovery bottle fully and purge at the bottle to ensure that there is no air within the line.

Zero the refrigerant scales to ensure correct recording of refrigerant amount being recovered and open the manifold to allow for the recovery of refrigerants.

Recovery of refrigerant can now commence. (Note that the recovery machine has no switching points on the machine therefore the machine must be switched on from outside the safe working zone.)

Once the manifold gauges show that the refrigerant has been recovered and showing a slight vacuum, continue to recover for a period of 5 minutes.

Close all equipment and record the amount of refrigerant recovered.

System Repair (Replace service valve connection point)

During any brazing process, the system must be purged with Oxygen Free Nitrogen.

Ensure that one point of the system is fully open by removing the schrader valve from the valve port to ensure free flow of OFN during the process and to ensure that there is no build up of pressure within the system during the brazing process.

Connect the OFN to the remaining port and start the purging process.

Ensure that you have the correct PPE including fire resistant gloves available when carrying our brazing works.

Un-braze / Sweat off the existing service port stem, replace with a new service port and braze the new service port in place. (Remembering to remove the valve core from the new valve prior to brazing)

Allow sufficient time for the brazed components to cool before stopping the purging process and replacing the Schrader valve.

Pressure Testing:

Pressure testing hydrocarbon systems to BS/EN378.

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

Carry out leak detection with suitable leak detection solution.

Before evacuation the system the remaining OFN must be vented to a well- ventilated area.

Evacuating the System

Care must be taken when using a standard vac pump on hydrocarbon systems. When setting up to evacuate the system you must ensure that the vac pump is in the ON position and can only be energised from outside of the safe working area.

With the use of a suitable Torr gauge, a vacuum of less than 2000 microns/2Torr must be achieved.

Once the required vacuum of the system has been archived, the vacuum should be protected by closing the valve on the vac pump and service valves on the manifold set. The vac pump should only be switched off outside of the safe working zone.

Charging the System:

When charging with hydrocarbon refrigerants you will require scales with an accuracy of + /- 1%

To purge the lines when connected to the system you should open and close the refrigerant bottle and purge the line at the gauge manifold.

Open the refrigerant bottle, place on the scales and zero the scales to ensure accurate recording of amount charged.

Once charge has been administered, the system should be energised and run for a few minutes before carrying out commissioning tasks.

Remove gauges from the systems and carry out a final direct leak check with the hydrocarbon leak detector.

Complete all service paperwork to finalise the process.