CM4 Four-Point Continuous Monitor
CM4 Technical Manual
8-13
2. Select 1 to toggle the pump On. A new pressure counts value
is displayed. This value is the “normal reading.” You will use
this value as a base to set the High and Low Limits.
3. Select 2 to set the High and Low limits. The display will
show:
LIMITS HI = 500 LO = 400
The cursor flashes under the first number of the high limit. Using the
arrow keys, moves the cursor location left or right. Decimal values 0-9
can also be entered.
4. Set the High Limit value. The recommended default value
is 52 +/-12 counts above the “normal reading,” allowing the
instrument as installed to exhaust the total flow up to a head
pressure of +1 PSIG (52 torr). Vacuum levels that are above
the set point may indicate high exhaust pressure, blocked
exhaust, low capacity pump, or low supply vacuum. The total
flow is reduced, affecting transport times and flow rate through
the Chemcassette
®
. This is due to low differential pressures
across the orifice of each point.
5. Set the Low Limit value. The default value recommended is 52
+/-12 counts below the “normal reading,” allowing the instrument
to indicate a 25% loss of total flow. Vacuum levels below the
limit indicates too much vacuum is detected. Possible causes
for this condition are blocked filters at the end of a sample line,
internal blocking of the orifices, or a blocked sample line. The
vacuum level is produced by pump capacity and the limiting
orifice used in each point. Adding four 300-foot sample lines
increases the total vacuum level, changing the count value
approximately -15 counts or 1/2 inch HG (12 torr).
NOTE:
Setting the limits to 0 will disable the fault being issued.
Once the high and low limits have been selected, press ENTER to store the
values. The message “Pump Limits Updated” is printed along with the Time/
Date/Serial Number. Pressing ESCAPE will exit the routine, returning the
values to pre-programmed levels and not printing any message.
The pump limits are also incorporated into the Service Mode Diagnostics
4.3 printout. The pump limits are also listed on the system configuration
printout (
2.6 Print Config
).
NOTE:
If at any time the system is reset to factory defaults (Function
4.4–RESET SYSTEM), this procedure will need to be redone
since the low and high limit values will be reset to factory
default values.
8.10 Function 4.9 – Reboot
A reboot function has been added to allow rebooting without cycling
Model CM4 power. Figure 8-5 shows the prompts displayed.
Display
Function
9 - REBOOT
Reboot
ENTER CODE 9XXXX
Appears only if menu password is enabled via Section 3.6.2
SAVE CONFIG 1=Y 0=NO Offer to backup configuration
CONF SAVED INTERNALLY Confirms that a backup was performed. Also a line will be printed:
CONFIGURATION SAVED INTERNALLY
RESTARTING
CM4
Reboot display
Figure 8-5: Reboot Function Prompts
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