What is the goal
Evacuation reduces non-condensable gas and water vapor pressure in the circuit. Humidity and air can compromise reliability, oil, rolling organs and performance. The target, the duration of the test and the procedure must come from the manufacturer of the specific unit: REFTHE does not have a single threshold as a rule for each plant.
The leak-tightness test and resistance is performed with the means and limits prescribed by the manufacturer and the legislation. The evacuation comes after a completed and documented test; He doesn't replace it.
Preparation before pump
- confirms that previous evidence is concluded and that the circuit is ready;
- verify compatibility of pump, oil, pipes, fittings and valves;
- reduce unnecessary restrictions using tubes suitable for vacuum and effective path;
- connect, if provided, both sides to limit bottlenecks;
- place the vacuum meter on the system, away from the pump, so measure the circuit and not only what happens at the pump's suction;
- check sealing and cleaning of the connection set.
Reasoned sequence
- Start and look. The descent curve contains information: an early arrest may indicate restriction, loss, degraded pump oil or significant moisture.
- Reach the manufacturer's target. Do not stop at the pump display; consider measuring point, stability and plant volume.
- Isolate correctly. Separate the pump without introducing air and observe the variation with the vacuometer still connected to the circuit.
- Play the lift. Fast and continuous growth is compatible with a loss or problem in the set. A slower growth that tends to stabilize can indicate degassing or residual humidity. It is a qualitative indication, to be compared with the procedure provided.
- Documenta. Record minimum value, time, insulation curve, temperature, connection configuration and tool.
The lift after insulation checks the stability of the vacuum under test conditions and can signal loss, moisture or degassing. It does not demonstrate mechanical resistance and does not replace the leak-tightness test in prescribed pressure, performed before evacuation with fluid, limits and duration provided for the plant.
| COMPORTAMENTO | WHAT CAN INDICATE? | SUCCESSIVO CONTROL |
|---|---|---|
| Very slow descent from the beginning | Restrictive pipes, closed valve, fitting, pump or high volume | Configuration, effective flow, oil and links |
| The target is reached at the pump but not in the system | incorrect measurement location or limited route | Move the vacuometer and reduce restrictions according to procedure |
| Quick recovery after insulation | Loss in the circuit or service set | Isolate and check separately components and connections |
| Slow risalita that flattens | compatible moisture or degassing | Continue according to manual, evaluate temperature and stability |
What not to do
Do not use oxygen, compressed air or unauthorized gas to pressurize the circuit. Do not start the vacuum compressor. Do not consider the pump operating time as sufficient proof and do not break the vacuum with a refrigerant or gas without following the expected sequence. Also check the specific requirements for flammable or high-pressure refrigerants.
Some specific drive manuals use 500 microns as targets, but other systems and procedures may require different criteria. The document applicable to the equipment always prevails.
Equipment that influences the result
Pump with proper flow rate, oil in good condition, reliable vacuum gauge, large passage tubes and valve core tools can drastically change process quality and time. Section Tools & equipment these products will be compared for application, compatibility and maintenance, not only for price.
Official primary sources
- Danfoss — Optyma Plus Drives, Application Practical guides 2018 (PDF) )
- FielPPEece — A2L documentation: pressure test, evacuation decay and test ↗
Resource REFTHE
See other official sources collected for installation →
The values of the Danfoss document mentioned are related to the Optyma Plus Drives family treated by the manual, not to all refrigeration plants.