BUSCH COBRA - Recommendations on Operation; Operating Frequency; Stop & Start Procedures; Operation with Argon

Commissioning | 7
Instruction Manual COBRA NC 2500 B WCV_EN_en 27 | 52
● After a few minutes of operation, perform an Oil Level Inspection [➔30].
● After a few minutes of operation, perform a Cooling Liquid Level Inspection [➔30].
As soon as the machine is operated under normal operating conditions:
● Measure the motor current and record it as reference for future maintenance and trouble-
shooting work.
7.1 Recommendations on Operation
7.1.1 Operating Frequency
● Operate the machine continuously at 35 ... 60 Hz (2100 ... 3600 min
-1
).
● For continuous operation at 20 ... 35 Hz, for example for stand-by purposes, an acceleration ramp
of 12 minutes for 0 … 60 Hz must be used (acceleration of 5 Hz per minute) or the inlet pressure
must be kept at >100 mbar for cooling purposes. The G 1/2 connection at the machine inlet spool
piece can be used to inject ambient cooling air.
● Operation below 20 Hz is not recommended.
● Maximum allowed operation frequency is 60 Hz (3600 min
-1
).
7.1.2 Stop & Start
Frequent stop-start operation to be avoided.
● Use acceleration ramp of 12 minutes for 0 … 60 Hz for start.
● Or, for fast start (30 seconds for 0 … 60 Hz), wait >60 minutes between stop and start.
7.1.3 Use with Argon
Pumping of high Argon concentrations (up to 50-80% of Argon) requires additional limits of opera-
tion:
● Rotational speed: max 50 Hz = 3000 min
-1
.
● Gas inlet temperature: max. 80 °C.
● Cooling gas: air or nitrogen.
● Temperature monitoring: standard setting.
7.2 Conveying Condensable Vapors
The machine is suitable for the conveyance of condensable vapors within the gas flow.
If condensable vapors are to be conveyed:
START
● Start the machine to warm it up
● Wait 30 minutes
● Open the inlet valve
● Perform the process
● Close the inlet valve
END
● Continuously drain condensate from the condensate drain plug (CD) of the silencer (SI) (Optional).