Normal Start-Up; Normal Operation - BeaconMedaes 4107 9006 25 Installation, Operation And Maintenance Instructions

"Oil-Less" Scroll Laboratory Air
3.0 System Operation

3.3 Normal Start-up

Facility shutoff valve - CLOSED.
Receiver bypass valve - CLOSED.
One air dryer off line with valves CLOSED; the
other air dryer on-line with the valves OPEN.
Main electrical power - ON.
Disconnect switches - ON.
Pump mode to "Automatic" on touchscreen
display.
Pressure increasing to 140 psi.
Check that each compressor shuts down as it
reaches its off -limit pressure.
Check that the mainline regulator is set for the
desired output pressure and adjust if necessary.
Slowly OPEN the facility shutoff valve.
NOTE: Opening the facility valve may cause a
pressure demand that brings the lag compressors
back on-line. This is a normal sequence.
NOTE: The Laboratory Air system is now on-line
and in the Normal Operating Mode (lead/lag
operation).
To verify dryer operation, refer to Appendix A for
desiccant dryers.

3.4 Normal Operation

3.4.1 Controls
During normal operation, all pumps should be
in "Automatic" mode to eff ectively control the
system. The controls monitor the system pressure
condition (see the table 3-1), starts and stops the
compressors depending on changing pressure
conditions, and automatically alternates the lead
position between compressor units.
In a typical duplex system, the control will signal
the lead compressor to start at 130 psig with
falling system pressure. If the one compressor can
carry the load, then the system pressure will rise to
140 psig. At this point, the control will turn off the
lead compressor. When the system pressure drops
again to 130 psig, the control will automatically
sequence the lead role to the other compressor
and will start it. This is known as "fi rst on/fi rst off "
instead of the more traditional "last on/fi rst off ".
With the "fi rst on/fi rst off " sequencing technique,
starts and stops on the compressor are minimized.
If the lead compressor runs continuously in
lead for more than 17 minutes, the control
will automatically sequence the compressor
attempting to evenly distribute the run time
among all available compressors. In a triplex or
quadruplex system, the operation is very similar
to the duplex operation described above.
NOTE: For a compressor to be considered
available to the system, its pump must be in the
"Automatic" position.
Table 3.1 System Pressure Factory Settings
System Pressure Settings
Lead
Lag
Backup Switch
NOTE: Factory settings may vary depending on
system size and confi guration.
For maintenance or other reasons, compressors can
operate in "Manual" position. The compressor(s)
in the "Manual" mode will start and stop
depending on backup pressure switch conditions.
NOTE: Any compressor in the "Manual" mode
will start and stop depending on backup pressure
switch condition.
3-5
Start Stop
(Close) (Open)
Varies 140 psig
120 psig Varies
110 psig 135 psig
4107 9006 25.11