Koeltechnicus Cat I flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Category I scope

Certification level covering all refrigeration systems and any F-gas charge, including hermetic, permanently sealed and open systems; required for leak checks, recovery, charging, servicing and decommissioning.

CO2e calculation

Multiply the refrigerant charge in kilograms by the gas's GWP from the regulation's Annex. Example: 5 kg R-404A at GWP 3922 equals 19,610 kg CO2e, i.e. 19.6 t CO2e.

Leak-check interval 5–50 t

Systems with a CO2e charge between 5 and 50 tonnes must be leak-checked at least every 12 months; with a verified leak-detection system the interval becomes 24 months.

Leak-check interval 50–500 t

Systems charged with 50 to 500 t CO2e require leak checks at least every 6 months; a verified leak-detection system extends the interval to 12 months.

Leak-check interval above 500 t

Systems containing 500 t CO2e or more must be checked at least every 3 months; with a verified leak-detection system the interval is 6 months.

Leak record retention

Records of refrigerant quantities, CO2e, leak-check dates and results, and recovered or charged amounts must be kept for at least five years and shown on request.

Recovery efficiency thresholds

Before dismantling, recover at least 95% of the charge for systems of 10 kg or more, and 98% for hermetically sealed equipment, using certified recovery equipment.

Reuse of recovered refrigerant

Recovered F-gas may be reused only by certified undertakings after documented recycling or reclamation; otherwise it must be destroyed or delivered to an authorised handler.

Certificate validity

F-gas certificates are personal, tied to the holder, and valid for a limited period set by the national scheme, typically five years, after which reassessment or refresher training is required.

GWP of common refrigerants

Regulatory GWP values include R-404A 3922, R-410A 2088, R-134a 1430, R-32 675, R-407C 1774 and R-744 (CO2) 1; always use the current Annex values.

Prohibited deliberate venting

Deliberate release of fluorinated greenhouse gases to the atmosphere is prohibited; refrigerant must be recovered, and only trace amounts from service connections are tolerated.

Certified company obligation

Companies performing covered work must employ certified personnel and hold the necessary equipment; the certificate proves individual competence, not company authorisation.

Superheat definition

Superheat is the suction or evaporator outlet temperature minus the evaporating saturation temperature at the measured pressure; it proves the refrigerant is fully vapour before the compressor.

Subcooling definition

Subcooling is the condensing saturation temperature minus the liquid line temperature; it confirms the refrigerant is fully liquid before the expansion device.

Typical TEV superheat

A thermostatic expansion valve is normally set for 5 to 8 K evaporator superheat; too little risks liquid floodback, too much reduces evaporator capacity and raises discharge temperature.

Triple evacuation procedure

Evacuate below 1000 micron, break the vacuum with dry nitrogen, repeat at least twice, then evacuate to 500 micron or lower and perform a standing vacuum test.

Standing vacuum test

After evacuation to 500 micron, isolate the pump and observe the gauge for 10 to 15 minutes; a small stable rise indicates moisture or a leak needing investigation.

Non-condensable symptoms

Air or nitrogen in the system raises condensing pressure and discharge temperature while subcooling stays high; purge only with recovery equipment, never by venting refrigerant.

Undercharge symptoms

Insufficient charge shows low suction pressure, high superheat, bubbles in the sight glass, low subcooling and reduced capacity; locate and repair the leak before recharging.

Nitrogen pressure testing

Use dry, oxygen-free nitrogen only for strength and tightness tests, never oxygen or air; respect the system's maximum allowable pressure and test in stages.

Brazing with nitrogen purge

Pass dry nitrogen through the pipe while brazing to displace air and prevent internal oxidation scale, which can block expansion devices and damage the compressor.

Electronic leak detection

Electronic detectors locate small leaks at joints, valves and flare connections; confirm findings with soap solution or a pressure test before opening the circuit.

Recovery cylinder filling limit

Never fill a recovery cylinder above 80% of its capacity by weight of liquid, and label it with the refrigerant type and whether the contents are recycled or reclaimed.

Pump-down and isolation

Pump-down moves refrigerant into the receiver or condenser and isolates it before service; verify isolation valves hold and pressures are released before opening any joint.

Three-phase compressor rotation

Confirm correct rotation direction before charging; reverse rotation gives no oil pressure, high noise and possible immediate compressor damage on scroll and screw machines.

High-pressure switch setting

The high-pressure cut-out must be set below the system's maximum allowable pressure with adequate margin; verify cut-out and manual reset function during commissioning and maintenance.

Oil management checks

Check oil level, colour and acidity; dark or acidic oil indicates overheating or moisture, and oil must be replaced with the grade specified by the compressor manufacturer.

Leak test before charging

Pressure-test with nitrogen and evacuate to prove tightness before charging refrigerant; charging first hides leaks and wastes gas that must then be recovered.

Condensing pressure control

In low ambient conditions, fan cycling, speed control or flooding maintains minimum condensing pressure so the expansion device keeps sufficient pressure differential to feed the evaporator.

Defrost termination control

Defrost must terminate on temperature or pressure, not time alone, so the coil is cleared of frost without adding heat to the refrigerated space or flooding the compressor.

Commissioning record content

Record evaporating and condensing pressures, superheat, subcooling, compressor currents, switch settings and charge quantity; these baselines make later fault diagnosis reliable.

Refrigerant cylinder handling

Store cylinders upright, secured and below the specified temperature, keep caps fitted, and never heat with open flame; use only cylinders approved for the refrigerant type.