Function 4.7 – Mda Service - Honeywell CM4 Technical Handbook

CM4 Four-Point Continuous Monitor
8.8 Function 4.7 – MDA Service
Purpose
MDA service engineers use this function to perform diagnostics and
service. This function requires a passcode.
8.9 Function 4.8 – Pump Limits
This mode allows you to program the limits that trigger the pump failure
fault. It also allows you to disable the limits, if desired.
8.9.1 Operation
The Pump Failure Fault is used to differentiate a supply vacuum fault
from a point-specific Flow Failure. The pump fault levels settings
should be made during the instrument installation to accommodate the
application. Setting the limit to "000" will disable the fault operation.
"Normal Reading"
The vacuum measurement in operation is used to determine clogged
filters, kinked inlet/exhaust tubing, or pump failure. With the pump
running a "normal reading" with no tubing attached to the CM4 monitor,
the reading should be 375-475 counts (13.8 to 17.5 inches Hg, or
350-495 torr), depending on current barometric pressure, voltage,
frequency, and other tolerances of the system. If you encounter
readings above or below these counts, a secondary check of point
flow rate is recommended. Point flow should be 2.8 Liters per minute
per point minimum with up to 300 feet of tubing connected.
Ambient Pressure Reading
The typical reading near sea level is approximately 800 counts for
an atmospheric reading of 28.4 to 30.5 inches of mercury (inches
Hg) (721-775 torr). The reading will vary approximately 26 counts per
inch (1 count per torr) change of barometric pressure. This variance
is included in selecting fault thresholds.
CM4 Technical Manual
Altitude should also be considered. At an altitude of 6000 feet (1800
m), and the pressure of 24 inches Hg would produce a reading of
approximately 651 counts. The capacity of the pump is reduced due
to the lower density air.
The transducer will display the count value of the absolute pressure on
the vacuum side. When the pump is not running, the ambient pressure
is represented. This reading can vary due to transducer tolerance,
atmospheric pressure, altitude, or differential pressures developed
between sample and exhaust connections of the system.
NOTE:
Always use 3/16-inch (4.7 mm) I.D. 1/4-inch (6.35 mm) O.D.
FEP Teflon tubing for sample lines, 300 ft. (90 m) maximum
per point. Use 3/16-inch (4.7 mm) I.D. 1/4-inch (6.35 mm) O.D.
tubing for exhaust, 50 ft. (15 m) maximum.
8.9.2 Set-up
Instructions
1. A c c e s s S e r v i c e M o d e 4 . 8 i n t h e S E R V I C E
(4–SERVICE) menu. The display will show:
PRESSURE CTS= 0800
The decimal value of the vacuum transducer is displayed
and updated every 1 second. This value is in raw electronic
counts, and does not represent flow rate of cc/min. This display
alternates with the display shown below until a 1, 2, 3, or
ESCAPE is selected.
1 = PUMP 2 = LIMIT 3= LIT
Selecting ESCAPE exits the mode and returns the software to the
Service menu. Selecting 1 toggles the pump On or Off. Selecting 2
switches off the pump and accesses the pump limits settings. Selecting
3 is for Sample Line Integrity Option, (see
8-12
Section 10.3).