Bitzer ST-140-1 Mode D'emploi page 54

5 Pipe layout and further system components
DANGER
Risk of bursting of components and pipes due to liquid overpressure.
Serious injuries are possible.
Make sure not to exceed maximum admissible pressures!
NOTICE
!
!
Danger of compressor failure due to flooding with oil at standstill!
Place the solenoid valve in the oil injection line directly next to the compressor (exceptions are OS.85 and
HS.85, they have an internal oil stop valve).
For CS. compressors: Position the solenoid valve directly before the oil inlet connection of the compressor
and control it electrically in parallel with the compressor contactor (i.e. the solenoid valve is closed when the
compressor is stopped).
For all oil connections which are installed subsequently:
NOTICE
!
!
Risk of refrigerant loss!
Prior to commissioning the system, check newly mounted pipes for pressure strength and tightness!
• Place the oil cooler in the immediate vicinity of the compressor.
• Design the pipe layout in such a way that no gas cushions can form and a rearward emptying of the oil reservoir
into the oil separator during standstill is excluded (place the oil cooler preferably below the compressor / oil sep-
arator).
• To simplify maintenance of the oil cooler, it is recommended to install shut-off valves (ball valves) in the oil lines.
• A sight glass for oil flow monitoring is recommended.
• For CSH compressors with a remotely placed oil cooler or if the cleanliness of the components is not ensured,
an oil filter is required additionally.
• Oil coolers must be controlled thermostatically ( Thermostatic control of the oil cooler ).
Oil bypass
For rapid heating of the oil circuit and reduction of pressure loss with cold oil, an oil bypass (possibly also heating
of the cooler at standstill) is absolutely necessary if:
• the oil volume of cooler and oil lines is > 25 dm
volume of cooler and oil lines is more than the compressor oil charge (for CSH compressors)
• the oil temperature in the cooler can drop below 20°C during longer standstill periods (e.g. if the oil cooler is in-
stalled outdoors or if it is integrated in the condenser)
The oil mixing valve should have a modulating control function. It is a temperature-controlled three-way or flow reg-
ulating valve and is shown in the system diagrams as: . The use of a solenoid valve (intermittent control) requires
maximum response sensitivity of the control thermostat and minimum switching differential (effective temperature
fluctuation <10 K).
The oil-side pressure loss in the cooler and pipes should not exceed 0.5 bar in normal operation.
In combination with an automatic pump-down system, increased switching cycles can result. They must be limited
to the maximum number of starts per hour by setting the low-pressure limiter and the pause time (time relay) ac-
cordingly, as specified in the relevant operating instructions (see list: Introduction ). For open drive compressors,
observe the specifications of the motor manufacturer. Depending on the operating mode, a single pump-down be-
fore switching off may be sufficient.
ST-140-1 // PDF Download
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(e.g. parallel compounds with common oil cooler) or the oil
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