Commissioning - Tecumseh SH4576Z Instructions D'utilisation

High and low pressure switches
The HP and LP pressure switches can be fitted to non-isolating pressure suction and discharge connection
points. They may be connected either to the contactor windings (electro-mechanical regulation) or to the
digital inputs of a controller (electronic regulation).
Connect pressure switches directly to isolating pressure connection points via service valves is
strictly prohibited. These may be closed and therefore make the pressure switches operate in a random
way.
De-activating the safety system can cause explosions, damage to equipment, personal injury or
even death.
Crankcase heater
Comply with the supply voltage for oil heaters. The supply must be inverted with the compressor contactor
to prevent it remaining switched on during operation of the installation.

-6 - Commissioning

If your starting procedure specifies a pressurisation test of the refrigerating circuit, it can be done with the
compressor valves open, if, and only if:
 The test pressure is lower than 30 bars on the HP side.
 The test pressure is lower than 20.5 bars on the LP side.
The sealing test must be done in accordance with standard EN378-2, within the limits of the maximum
permitted compressor pressure. This sealing test must be done with O.F. nitrogen.
Carrying out the sealing test with refrigerant is prohibited. Refrigerants are not leak detection
gases. Releasing refrigerants into the atmosphere is prohibited by law. In cases of a nitrogen/HFC mixture,
releasing this into the atmosphere is also prohibited; it must be recovered and re-processed, in accordance
with the same rules that apply to processing HFCs.
6.1 – No-load draw
Running the refrigeration circuit at no load must be done using best practice rules.
For a circuit that always contains pressurised nitrogen, always de-gas to obtain atmospheric pressure.
For optimum draw, use connectors on both the LP and HP sides.
After opening all the service and solenoid valves, connect to the two-stage vacuum pump.
Make the vacuum in accordance with regulation EN378-2.
Tecumseh recommends pulling against the vacuum until a residual pressure of approximately 200 microns
is achieved (height of mercury). Once the vacuum level is reached, pressure must remain stable at + 20%
maximum of the value obtained with the pump in operation. If the pressure rises again, this is a sign of:
 The presence of humidity in the system.
 The existence of a leak.
In the latter case, located the leak and repeat the vacuum drawing operation.
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